From f10e97198e31b4c0433c753803fa263d790fdbfb Mon Sep 17 00:00:00 2001
From: Rafael Brandao <rmello@br.ibm.com>
Date: Thu, 12 Aug 2021 11:55:57 -0300
Subject: [PATCH 01/24] First commit for the new Trails implementation

---
 package.json |   3 +-
 trail.js     | 194 ++++++++++++++++++++++++++++++++-------------------
 2 files changed, 126 insertions(+), 71 deletions(-)

diff --git a/package.json b/package.json
index dc41578..fa2db2a 100644
--- a/package.json
+++ b/package.json
@@ -41,7 +41,8 @@
     "nearley": "^2.20.1",
     "request": "^2.88.0",
     "request-promise-native": "^1.0.8",
-    "shortid": "^2.2.14"
+    "shortid": "^2.2.14",
+    "linked-list": "git+ssh://git@github.ibm.com:keg-core/linked-list.git"
   },
   "license": "MIT",
   "repository": {
diff --git a/trail.js b/trail.js
index 7e640bb..06626cb 100644
--- a/trail.js
+++ b/trail.js
@@ -5,6 +5,8 @@
 
 'use strict'
 
+const {List, Item} = require('linked-list');
+
 const shortid   = require('shortid');
 const Types     = require('./types');
 const HKEntity  = require('./hkentity');
@@ -12,14 +14,10 @@ const Connector = require('./connector');
 const Link      = require('./link');
 const RoleTypes = require('./roletypes');
 
-const CONNECTOR_NAME = 'occurs';
-
-const vConnector = new Connector (CONNECTOR_NAME, 'f');
-vConnector.addRole ('sub', RoleTypes.SUBJECT);
-vConnector.addRole ('obj', RoleTypes.OBJECT);
 
-function Trail (id, parent)
+function Trail (id, actions, parent)
 {
+
   if(arguments[0] && typeof arguments[0] === 'object' && isValid(arguments[0]))
   {
     let trail = arguments[0];
@@ -29,8 +27,11 @@ function Trail (id, parent)
     this.properties = trail.properties || {};
     this.metaproperties = trail.metaproperties || {};
     this.interfaces = trail.interfaces || {};
-    this.children = trail.children || [];
-    _loadSteps.call (this);
+    this.actions = trail.actions || [];
+
+    if (this.actions && Object.keys(this.actions).length > 0) {
+      loadActions.call (this); 
+    }
   }
   else
   {
@@ -39,57 +40,43 @@ function Trail (id, parent)
     this.interfaces = {};
     this.properties = {};
     this.metaproperties = {};
-    this.children = [];
-    this.steps = [];
+    this.actions = actions || [];
   }
 
   this.type = Types.TRAIL;
 }
 
 Trail.prototype = Object.create (HKEntity.prototype);
-Trail.prototype.constructor = Trail;
 
-Trail.prototype.addStep = function (key, properties)
-{
-  let ts = properties.begin || new Date().toISOString();
-  properties.begin = ts;
+Object.assign(Trail.prototype, List.prototype); // Multiple inheritance with assign
 
-  if (this.steps.length > 0)
-  {
-    let lastStep = this.steps[this.steps.length - 1].key;
-    if (! this.interfaces[lastStep].properties.end )
-    {
-      this.interfaces[lastStep].properties.end = ts;
-    }
-  }
+Trail.prototype.constructor = Trail;
 
-  this.steps.push ({key: key, begin: ts});
-  this.addInterface (key, 'temporal', properties);
-}
 
-Trail.prototype.addInterface  = function (key, type, properties)
+// Update a given action in trail
+Trail.prototype.updateAction = function (oldAction, newAction)
 {
-  this.interfaces[key] = {type: type, properties: properties}
+  oldAction.prepend(newAction);
+  oldAction.detach();
 }
 
-Trail.prototype.createLinksFromSteps = function ()
+// Remove an action from trail using its reference
+Trail.prototype.removeAction = function (action) 
 {
-	let vEntities = [vConnector];
-
-	for (let key in this.interfaces)
-	{
-		let interProp = this.interfaces[key].properties;
-		if (!interProp) continue;
-
-		if (interProp.obj)
-		{
-			let l = new Link (shortid(), vConnector.id, this.parent);
-			l.addBind ('sub', interProp.obj, interProp.objInterface);
-			l.addBind ('obj', this.id);
-			vEntities.push (l);
-		}
-	}
-	return vEntities;
+    var action;
+    if(typeof(action) === 'string') {
+        this.action = this.search(action)
+        
+        //action not found
+        if(!this.action){
+            return
+        }
+    }
+    else { 
+        this.action = action;
+    }
+
+    this.action.detach();
 }
 
 Trail.prototype.serialize = function ()
@@ -100,40 +87,40 @@ Trail.prototype.serialize = function ()
       properties: this.properties,
       metaproperties: this.metaproperties,
       interfaces: this.interfaces,
+      actions: this.actions,
       type: this.type
   };
 }
 
-function _loadSteps ()
+function loadActions(actions = null)
 {
-  let steps = [];
-  for (let key in this.interfaces)
+  if(actions)
   {
-    let begin = new Date (Date.parse(this.interfaces[key].properties.begin));
-    let end = new Date (Date.parse(this.interfaces[key].properties.end));
-
-    this.interfaces[key].properties.begin = begin;
-    this.interfaces[key].properties.end = end;
-
-    steps.push ( { key: key, begin: begin } );
+    this.actions = actions;
+    return;
   }
 
-  steps.sort (
-    (a,b) =>
+  let actionArray = []
+  for (let i in this.actions) 
+  {
+    // create Action objects from parsed data
+    if (this.actions[i].hasOwnProperty("from") && 
+    this.actions[i].hasOwnProperty("to") && 
+    this.actions[i].hasOwnProperty("agent") &&
+    this.actions[i].hasOwnProperty("eventType"))
     {
-      if (a.begin < b.begin )
-      {
-        return -1;
-      }
-      if (a.begin > b.begin )
-      {
-        return 1;
-      }
+      let from = new TrailNode(this.actions[i].from.split('#')[0], this.actions[i].from.split('#').length > 1 ? this.actions[i].from.split('#')[1] : "lambda")
+      let to = new TrailNode(this.actions[i].to.split('#')[0], this.actions[i].to.split('#').length > 1 ? this.actions[i].to.split('#')[1] : "lambda")
+      let event = { "id": i, "type": this.actions[i].eventType, "properties": this.actions[i].eventProperties, "timestamp": new Date(parseInt(this.actions[i].hasTimestamp))}
+      let agent = this.actions[i].agent
 
-      return 0;
-    });
-
-  this.steps = steps;
+      actionArray.push(new Action(from, to, event, agent));
+    }
+  }
+  if (actionArray.length>0)
+  {
+    this.actions = actionArray; 
+  }
 }
 
 function isValid(entity)
@@ -151,7 +138,74 @@ function isValid(entity)
   return isValid;
 }
 
+// TrailNode is basically an envelope for a hknode and a target anchor
+class TrailNode {
+  constructor(nodeId, targetAnchor) {
+    this.nodeId = nodeId;
+    this.targetAnchor = targetAnchor;
+  }
+
+  toString() {
+      return this.nodeId + "#" + this.targetAnchor;
+  }
+
+  toJSON() {
+    return this.nodeId + "#" + this.targetAnchor;
+  }
+}
+
+// actions hold references to source and destination trail 
+// nodes (along with their respective target anchors), 
+// the related event and an agent (user, system or content).
+class Action extends Item {
+  constructor(from, to, event, agent) 
+  {
+      super()
+      this.from = from;
+      this.to = to;
+      this.agent = agent;
+      this.event = event;
+
+      if(!this.event)
+      {
+        return
+      }
+
+      // create timestamp if needed
+      if(!this.event['timestamp'])
+      {
+          this.event['timestamp'] = new Date().getTime();
+      }
+
+      // get event id or create a new one
+      if(!this.event['id'] || this.event['id'] == '') 
+      {
+          this.event['id'] = this.event.type + '_' + this.event.timestamp;
+          this.id = this.event['id'];
+      }
+      else 
+      {
+          this.id = this.event['id'];
+      }
+  }
+
+  getTime()
+  {
+      return new Date(this.event['timestamp']).getTime();
+  }
+
+  toString() 
+  {
+      return "[" + new Date(this.event['timestamp']).toISOString() + "] " + this.from + " -- " + this.event['eventId'] + " (by " + this.agent + ") --> " + this.to;
+  }
+}
+
 Trail.type = Types.TRAIL;
 Trail.isValid = isValid;
 
-module.exports = Trail;
+
+module.exports = {
+  Action : Action,
+  List : Trail
+}
+

From b01ee370d46ebdca20341615e557917acb66976a Mon Sep 17 00:00:00 2001
From: Rafael Brandao <rmello@br.ibm.com>
Date: Thu, 12 Aug 2021 14:17:49 -0300
Subject: [PATCH 02/24] Avoid exposing List class from Trail module

---
 index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.js b/index.js
index 6d084e4..9f1566b 100644
--- a/index.js
+++ b/index.js
@@ -14,7 +14,7 @@ exports.Context        = require("./context");
 exports.Connector      = require("./connector");
 exports.Reference      = require("./reference");
 exports.Link           = require("./link");
-exports.Trail          = require("./trail");
+exports.Trail          = require("./trail").List;
 exports.HKEntity       = require("./hkentity");
 
 const Types            = require("./types");

From bb802643ab4475011f44f4547dd273f38f40072e Mon Sep 17 00:00:00 2001
From: Raphael Melo <raphael.melo.t@gmail.com>
Date: Wed, 18 Aug 2021 13:53:09 -0300
Subject: [PATCH 03/24] only exporting trail in trail.js

---
 trail.js | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/trail.js b/trail.js
index 06626cb..f3b1c9d 100644
--- a/trail.js
+++ b/trail.js
@@ -204,8 +204,5 @@ Trail.type = Types.TRAIL;
 Trail.isValid = isValid;
 
 
-module.exports = {
-  Action : Action,
-  List : Trail
-}
+module.exports = Trail;
 

From f6df1d857399a8a84bc25c7e8307a1037b1ef7ac Mon Sep 17 00:00:00 2001
From: Rafael Brandao <rmello@br.ibm.com>
Date: Wed, 18 Aug 2021 15:52:42 -0300
Subject: [PATCH 04/24] Removing List from require

---
 index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.js b/index.js
index 9f1566b..6d084e4 100644
--- a/index.js
+++ b/index.js
@@ -14,7 +14,7 @@ exports.Context        = require("./context");
 exports.Connector      = require("./connector");
 exports.Reference      = require("./reference");
 exports.Link           = require("./link");
-exports.Trail          = require("./trail").List;
+exports.Trail          = require("./trail");
 exports.HKEntity       = require("./hkentity");
 
 const Types            = require("./types");

From c7171285dfcb3d4580427fa222234f78465d832b Mon Sep 17 00:00:00 2001
From: Rafael Brandao <rmello@br.ibm.com>
Date: Tue, 24 Aug 2021 15:30:55 -0300
Subject: [PATCH 05/24] Adding in-memory functions

Changing TrailNodes in Actions to objects instead of strings
---
 trail.js | 209 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 190 insertions(+), 19 deletions(-)

diff --git a/trail.js b/trail.js
index f3b1c9d..dafc76b 100644
--- a/trail.js
+++ b/trail.js
@@ -79,17 +79,171 @@ Trail.prototype.removeAction = function (action)
     this.action.detach();
 }
 
-Trail.prototype.serialize = function ()
-{
-  return {
-      id: this.id,
-      parent: this.parent,
-      properties: this.properties,
-      metaproperties: this.metaproperties,
-      interfaces: this.interfaces,
-      actions: this.actions,
-      type: this.type
-  };
+// aliases `in` and `out` represent the entrypoint and
+// output TrailNodes for this trail, which conceptually is
+// done through the use of Port elements in Hyperknowledge
+Trail.prototype.in = function(from) {
+  if (from)
+  {
+    this.head.from = from;
+  }
+    
+  return this.head.from;
+}
+Trail.prototype.out = function(to) {
+  if (to)
+  {
+    this.tail.to = to;
+  }
+    
+  return this.tail.to;
+}
+
+Trail.prototype.join = function(delimiter) {
+    return this.toArray().join(delimiter)
+}
+
+// Update a given action in the trail
+Trail.prototype.update = function(action, newAction){
+    action.prepend(newAction)
+    action.detach()
+}
+
+// Remove an action from the trail using its reference
+Trail.prototype.remove = function(action) {
+    var action
+    if(typeof(action) === 'string') {
+        this.action = this.search(action)
+        
+        //action not found
+        if(!this.action){
+            return
+        }
+    }
+    else { 
+        this.action = action 
+    }
+
+    this.action.detach()
+}
+
+// Get `num` actions (or the available ones) before `position`
+Trail.prototype.getPrev = function(position, num=1){
+    //check if it is a valid position
+    if (position >= this.size || position <= 1 || this.size <= 1){
+        return;
+    }
+
+    // get actions
+    var action = this.toArray()[position]
+    var resultSet = []
+    while(action && action.prev){
+        if (resultSet.length >= num) {
+            if(resultSet.length == 1 && num == 1){
+                return resultSet[0]
+            }
+            return resultSet
+        }
+        else {
+            resultSet.push(action.prev)
+        }
+        
+        action = action.prev
+    }
+
+    return resultSet
+}
+
+// Get `num` actions (or a n<num available ones) after `position`
+// if a number is not given, 1 is assumed
+Trail.prototype.getNext = function(position, num=1){
+    // check if it is a valid position
+    if (position >= this.size || position <= 1 || this.size <= 1){
+        return;
+    }
+
+    // get actions
+    var action = this.toArray()[position]
+    var resultSet = []
+    while(action && action.next){
+        if (resultSet.length >= num) {
+            if(resultSet.length == 1 && num == 1){
+                return resultSet[0]
+            }            
+        }
+        else {
+            resultSet.push(action.next)
+        }
+        
+        action = action.next
+    }
+
+    return resultSet
+}
+
+// Get the position of an action in the list,
+// it might be useful for pagination. Returns 
+// -1 in case action is not found in the list
+Trail.prototype.getPositionOf = function(action){
+    //search action by eventId
+    var array = this.toArray()
+    for (var i = 0; i < this.size; i++) {
+        if(array[i].event["eventId"] == action.event["eventId"]){
+            return i
+        }
+    }
+    return -1
+}
+
+// Get an action at specified position
+// a position = 0 is equivalent to trail.head
+Trail.prototype.getActionAt = function(position) {
+    //check if it is a valid position
+    if (position < 0 || position >= this.size ){
+        return;
+    }
+
+    //return action by position in array
+    return this.toArray()[position]
+}
+
+// Search for action(s) either by an event identifier or by filters
+Trail.prototype.search = function(eventId = null, filters){        
+    if (!filters && eventId instanceof String) {
+        filters = {'from': null, 'fromAnchor': 'lambda', 'to': null, 'toAnchor': 'lambda'}
+    }
+    else if (!filters && eventId instanceof Object){
+        filters = eventId
+        eventId = null
+    }
+    
+    // nothing to be found
+    if (!eventId && !filters['from'] && !filters['to']){
+        return
+    }
+
+    // search actions by eventId
+    var array = this.toArray()
+    if (eventId){
+        for (var i = 0; i < this.size; i++) {
+            if(array[i].event["eventId"] == eventId){
+                return array[i]
+            }
+        }
+        return
+    }
+
+    // search actions by filters
+    var resultSet = []
+    for (var i = 0; i < this.size; i++) {
+        if((filters['from'] && filters['to']) && array[i].from == filters['from'] && array[i].to == filters['to']){
+            resultSet.push(array[i])
+        }
+        else if(array[i].from == filters['from'] || array[i].to == filters['to']){
+            resultSet.push(array[i])
+        }
+    }
+    return resultSet
 }
 
 function loadActions(actions = null)
@@ -109,9 +263,9 @@ function loadActions(actions = null)
     this.actions[i].hasOwnProperty("agent") &&
     this.actions[i].hasOwnProperty("eventType"))
     {
-      let from = new TrailNode(this.actions[i].from.split('#')[0], this.actions[i].from.split('#').length > 1 ? this.actions[i].from.split('#')[1] : "lambda")
-      let to = new TrailNode(this.actions[i].to.split('#')[0], this.actions[i].to.split('#').length > 1 ? this.actions[i].to.split('#')[1] : "lambda")
-      let event = { "id": i, "type": this.actions[i].eventType, "properties": this.actions[i].eventProperties, "timestamp": new Date(parseInt(this.actions[i].hasTimestamp))}
+      let from = new TrailNode(JSON.parse(this.actions[i].from).nodeId, JSON.parse(this.actions[i].from).nodeType, JSON.parse(this.actions[i].from).targetAnchor);
+      let to = new TrailNode(JSON.parse(this.actions[i].to).nodeId, JSON.parse(this.actions[i].to).nodeType, JSON.parse(this.actions[i].to).targetAnchor);
+      let event = { "id": i, "type": this.actions[i].eventType, "properties": JSON.parse(this.actions[i].eventProperties), "timestamp": new Date(this.actions[i].hasTimestamp)}
       let agent = this.actions[i].agent
 
       actionArray.push(new Action(from, to, event, agent));
@@ -138,10 +292,26 @@ function isValid(entity)
   return isValid;
 }
 
+
+Trail.prototype.serialize = function ()
+{
+  return {
+      id: this.id,
+      parent: this.parent,
+      properties: this.properties,
+      metaproperties: this.metaproperties,
+      interfaces: this.interfaces,
+      actions: this.actions,
+      type: this.type
+  };
+}
+
+
 // TrailNode is basically an envelope for a hknode and a target anchor
 class TrailNode {
-  constructor(nodeId, targetAnchor) {
+  constructor(nodeId, nodeType, targetAnchor) {
     this.nodeId = nodeId;
+    this.nodeType = nodeType;
     this.targetAnchor = targetAnchor;
   }
 
@@ -149,9 +319,9 @@ class TrailNode {
       return this.nodeId + "#" + this.targetAnchor;
   }
 
-  toJSON() {
-    return this.nodeId + "#" + this.targetAnchor;
-  }
+  // toJSON() {
+  //   return this.nodeId + "#" + this.targetAnchor;
+  // }
 }
 
 // actions hold references to source and destination trail 
@@ -202,7 +372,8 @@ class Action extends Item {
 
 Trail.type = Types.TRAIL;
 Trail.isValid = isValid;
-
+// Trail.Action = Action;
+// Trail.TrailNode = TrailNode;
 
 module.exports = Trail;
 

From 906b5adf5b854d3192b85c15a9864fd8ef7d9f67 Mon Sep 17 00:00:00 2001
From: Raphael Melo Thiago <raphaelt@br.ibm.com>
Date: Wed, 25 Aug 2021 16:54:30 -0300
Subject: [PATCH 06/24] Adding fetch trail to hkdatasource

---
 datasource/hkdatasource.js | 47 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/datasource/hkdatasource.js b/datasource/hkdatasource.js
index 00ba0fc..790fc02 100644
--- a/datasource/hkdatasource.js
+++ b/datasource/hkdatasource.js
@@ -463,6 +463,53 @@ HKDatasource.prototype.fetchContext = function(context, callback = () => {})
 	});
 }
 
+/**
+ * @callback GetTrailCallback
+ * @param {string} err An error object that indicate if the operation was succesful or not
+ * @param {object} trail 
+ */
+/**
+ * Fetch trail
+ *
+ * @param {string} trailId The trail id to retrieve their nested entities.
+ * @param {GetTrailCallback} callback Callback with the entities
+ */
+
+ HKDatasource.prototype.fetchTrail = function(trailId, callback = () => {})
+ {
+	 let url = this.url + "repository/" + this.graphName + "/trail/" + encodeURIComponent(trailId);
+ 
+	 request.get(url, this.options, (err, res) =>
+	 {
+		 // console.log(res.body);
+		 if(!err)
+		 {
+			 if(requestCompletedWithSuccess (res.statusCode))
+			 {
+				 try
+				 {
+					 let entities = convertEntities(res.body);
+					 callback(null, entities[trailId]);
+				 }
+				 catch(exp)
+				 {
+					 console.log(exp);
+					 callback(exp);
+				 }
+			 }
+			 else
+			 {
+				 callback(`Server responded with ${res.statusCode}. ${res.body}`);
+			 }
+ 
+		 }
+		 else
+		 {
+			 callback(err);
+		 }
+	 });
+ }
+
 /**
  * Filter entities using CSS pattern `(TODO: document it better)`
  *

From 6f1709c04a915777f8fff6a7d3ac1a4a456f69a2 Mon Sep 17 00:00:00 2001
From: Rafael Brandao <rmello@br.ibm.com>
Date: Wed, 1 Sep 2021 15:59:55 -0300
Subject: [PATCH 07/24] Sorting actions based on timestamps

---
 trail.js | 51 ++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 46 insertions(+), 5 deletions(-)

diff --git a/trail.js b/trail.js
index dafc76b..6845759 100644
--- a/trail.js
+++ b/trail.js
@@ -82,7 +82,7 @@ Trail.prototype.removeAction = function (action)
 // aliases `in` and `out` represent the entrypoint and
 // output TrailNodes for this trail, which conceptually is
 // done through the use of Port elements in Hyperknowledge
-Trail.prototype.in = function(from) {
+Trail.prototype.in = function(from = null) {
   if (from)
   {
     this.head.from = from;
@@ -90,7 +90,7 @@ Trail.prototype.in = function(from) {
     
   return this.head.from;
 }
-Trail.prototype.out = function(to) {
+Trail.prototype.out = function(to = null) {
   if (to)
   {
     this.tail.to = to;
@@ -248,13 +248,17 @@ Trail.prototype.search = function(eventId = null, filters){
 
 function loadActions(actions = null)
 {
-  if(actions)
+
+  // use array of actions if passed
+  if(actions && Array.isArray(actions))
   {
-    this.actions = actions;
+    this.actions = sort(actions);
+    
     return;
   }
 
   let actionArray = []
+  let actionIds = []
   for (let i in this.actions) 
   {
     // create Action objects from parsed data
@@ -270,11 +274,27 @@ function loadActions(actions = null)
 
       actionArray.push(new Action(from, to, event, agent));
     }
+    else if(this.actions[i].hasOwnProperty("hasTimestamp"))
+    {
+      // all we got is event's id and timestamp
+      actionIds.push(new Action(null, null, {"id": i, "timestamp": new Date(this.actions[i].hasTimestamp)}, null));
+    }
   }
+  
   if (actionArray.length>0)
   {
-    this.actions = actionArray; 
+    this.actions = sort(actionArray);
+  }
+  else if (actionIds.length>0)
+  {
+    actionIds = sort(actionIds);
+
+    for (let i in actionIds)
+    {
+      this.actions.push(actionIds[i].id);
+    }
   }
+  
 }
 
 function isValid(entity)
@@ -292,6 +312,25 @@ function isValid(entity)
   return isValid;
 }
 
+function sort(actions = null)
+{
+  if (actions && Array.isArray(actions) && actions[0] instanceof Object)
+  {
+    // sort and return object array based on timestamp
+    return actions.sort(function(action1, action2)
+    {
+      return new Date(action1.event['timestamp']) - new Date(action2.event['timestamp']);
+    });
+  }
+  else if (actions && Array.isArray(actions) && this.actions[0] instanceof Action)
+  {
+    // sort Action array based on timestamp
+    return actions.sort(function(action1, action2)
+    {
+      return action1.event['timestamp'] - action2.event['timestamp'];
+    });
+  }
+}
 
 Trail.prototype.serialize = function ()
 {
@@ -372,6 +411,8 @@ class Action extends Item {
 
 Trail.type = Types.TRAIL;
 Trail.isValid = isValid;
+Trail.sort = sort;
+
 // Trail.Action = Action;
 // Trail.TrailNode = TrailNode;
 

From 748073ce0118a24211a50cd44a1ddee31f418167 Mon Sep 17 00:00:00 2001
From: GabrielaPC <gabrielapc@id.uff.br>
Date: Wed, 8 Sep 2021 13:25:54 -0300
Subject: [PATCH 08/24] Trail Internals now appear on the Inspector

---
 hkgraph.js | 36 ++++++++++++++++++++++--------------
 1 file changed, 22 insertions(+), 14 deletions(-)

diff --git a/hkgraph.js b/hkgraph.js
index 119dec0..463b4f1 100644
--- a/hkgraph.js
+++ b/hkgraph.js
@@ -28,10 +28,10 @@ function HKGraph()
 	this.linkMap = {};
     this.refMap = {};
     this.orphans = {};
-	this.contextMap = {};
+	this.compositeNodeMap = {};
     this.relationless = {};
 
-	this.contextMap[null] = {};
+	this.compositeNodeMap[null] = {};
 
 	this.generateId = generateId;
 }
@@ -72,7 +72,7 @@ HKGraph.prototype.setEntity = function(entity)
 		oldEntity.className = entity.className;
     }
 
-    if(entity.type === Types.NODE || entity.type === Types.REFERENCE || entity.type === Types.CONTEXT)
+    if(entity.type === Types.NODE || entity.type === Types.TRAIL || entity.type === Types.REFERENCE || entity.type === Types.CONTEXT)
     {
         
         oldEntity.interfaces = entity.interfaces;
@@ -86,7 +86,7 @@ HKGraph.prototype.setEntity = function(entity)
 		let oldParent = this.getEntity(oldEntity.parent);
 		if(oldParent)
 		{
-			delete this.contextMap[oldEntity.parent][oldEntity.id];
+			delete this.compositeNodeMap[oldEntity.parent][oldEntity.id];
 		}
 		else if (oldEntity.parent)
 		{
@@ -100,7 +100,7 @@ HKGraph.prototype.setEntity = function(entity)
 		let parent = this.getEntity(entity.parent);
 		if(parent || entity.parent === null)
 		{
-			this.contextMap[entity.parent][entity.id] = entity;
+			this.compositeNodeMap[entity.parent][entity.id] = entity;
 		}
 		else if (entity.parent)
 		{
@@ -164,11 +164,11 @@ HKGraph.prototype.addEntity = function(entity)
                 {
                     newEntity = new Context(entity);
                     this.contexts[entity.id] = newEntity;
-					this.contextMap[entity.id] = {};
+					this.compositeNodeMap[entity.id] = {};
 
                     if(this.orphans.hasOwnProperty(entity.id))
                     {
-						this.contextMap[entity.id] = this.orphans[entity.id];
+						this.compositeNodeMap[entity.id] = this.orphans[entity.id];
                         delete this.orphans[entity.id];
                     }
                 }
@@ -180,6 +180,13 @@ HKGraph.prototype.addEntity = function(entity)
                 {
                     newEntity = new Trail(entity);
                     this.trails[entity.id] = newEntity;
+					this.compositeNodeMap[entity.id] = {};
+
+                    if(this.orphans.hasOwnProperty(entity.id))
+                    {
+						this.compositeNodeMap[entity.id] = this.orphans[entity.id];
+                        delete this.orphans[entity.id];
+                    }
                 }
                 break;
             }
@@ -247,9 +254,9 @@ HKGraph.prototype.addEntity = function(entity)
 		// Set parent
 		if (entity.type !== Types.CONNECTOR) 
 		{	
-			if (this.contextMap.hasOwnProperty(newEntity.parent))
+			if (this.compositeNodeMap.hasOwnProperty(newEntity.parent))
 			{
-				this.contextMap[newEntity.parent][newEntity.id] = newEntity;
+				this.compositeNodeMap[newEntity.parent][newEntity.id] = newEntity;
 			}
 			else 
 			{
@@ -291,7 +298,7 @@ HKGraph.prototype.removeEntity = function(id)
 			case Context.type:
 			{
                 delete this.contexts[id];
-				delete this.contextMap[entity.id];
+				delete this.compositeNodeMap[entity.id];
 				break;
 			}
 			case Reference.type:
@@ -340,6 +347,7 @@ HKGraph.prototype.removeEntity = function(id)
             {
                 /* delete children trails? */
                 delete this.trails[id];
+				delete this.compositeNodeMap[entity.id];
                 break;
             }
 		}
@@ -349,9 +357,9 @@ HKGraph.prototype.removeEntity = function(id)
             delete this.orphans[entity.parent][id];
         }
 
-        if(this.contextMap.hasOwnProperty(entity.parent))
+        if(this.compositeNodeMap.hasOwnProperty(entity.parent))
 		{
-			delete this.contextMap[entity.parent][entity.id];
+			delete this.compositeNodeMap[entity.parent][entity.id];
 		}
 
 		if(this.bindsMap.hasOwnProperty(entity.id))
@@ -435,9 +443,9 @@ HKGraph.prototype.getReference = function(id, parent)
 
 HKGraph.prototype.getChildren = function(contextId)
 {
-	if(this.contextMap.hasOwnProperty(contextId))
+	if(this.compositeNodeMap.hasOwnProperty(contextId))
 	{
-		return this.contextMap[contextId];
+		return this.compositeNodeMap[contextId];
 	}
 	else
 	{

From 1e629566405f0d6898175665ab3b44314df249d8 Mon Sep 17 00:00:00 2001
From: Rafael Brandao <rmello@br.ibm.com>
Date: Tue, 21 Sep 2021 17:15:12 -0300
Subject: [PATCH 09/24] Improving use of linked-list lib for in-memory
 operations

---
 trail.js | 237 +++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 153 insertions(+), 84 deletions(-)

diff --git a/trail.js b/trail.js
index 6845759..aec2536 100644
--- a/trail.js
+++ b/trail.js
@@ -5,52 +5,53 @@
 
 'use strict'
 
-const {List, Item} = require('linked-list');
+const {List, Item}    = require('linked-list');
+// const List      = Linked.List;
+// const Item      = Linked.Item;
 
-const shortid   = require('shortid');
+// const shortid   = require('shortid');
 const Types     = require('./types');
 const HKEntity  = require('./hkentity');
-const Connector = require('./connector');
-const Link      = require('./link');
-const RoleTypes = require('./roletypes');
+// const Connector = require('./connector');
+// const Link      = require('./link');
+// const RoleTypes = require('./roletypes');
 
 
 function Trail (id, actions, parent)
-{
-
-  if(arguments[0] && typeof arguments[0] === 'object' && isValid(arguments[0]))
   {
-    let trail = arguments[0];
 
-    this.id = trail.id || null;
-    this.parent = trail.parent || null;
-    this.properties = trail.properties || {};
-    this.metaproperties = trail.metaproperties || {};
-    this.interfaces = trail.interfaces || {};
-    this.actions = trail.actions || [];
+    if(arguments[0] && typeof arguments[0] === 'object' && isValid(arguments[0]))
+    {
+      let trail = arguments[0];
 
-    if (this.actions && Object.keys(this.actions).length > 0) {
-      loadActions.call (this); 
+      this.id = trail.id || null;
+      this.parent = trail.parent || null;
+      this.properties = trail.properties || {};
+      this.metaproperties = trail.metaproperties || {};
+      this.interfaces = trail.interfaces || {};
+      this.actions = trail.actions || new List();
+
+      if (this.actions && Object.keys(this.actions).length > 0) {
+        loadActions.call(this); 
+      }
     }
-  }
-  else
-  {
-    this.id = id || null;
-    this.parent = parent || null;
-    this.interfaces = {};
-    this.properties = {};
-    this.metaproperties = {};
-    this.actions = actions || [];
-  }
+    else
+    {
+      this.id = id || null;
+      this.parent = parent || null;
+      this.interfaces = {};
+      this.properties = {};
+      this.metaproperties = {};
+      this.actions = actions || new List();
 
-  this.type = Types.TRAIL;
+    }
+
+    this.type = Types.TRAIL;
 }
 
 Trail.prototype = Object.create (HKEntity.prototype);
-
-Object.assign(Trail.prototype, List.prototype); // Multiple inheritance with assign
-
 Trail.prototype.constructor = Trail;
+// Trail.prototype = Object.assign(Trail.prototype, List.prototype); // Multiple inheritance with assign
 
 
 // Update a given action in trail
@@ -60,6 +61,24 @@ Trail.prototype.updateAction = function (oldAction, newAction)
   oldAction.detach();
 }
 
+// Add an action to a trail respecting timestamp ordering
+Trail.prototype.addAction = function (action) 
+{
+  var current = this.actions.head;
+
+  while (current)
+  {
+    if (new Date(current.event['timestamp']) - new Date(action.event['timestamp']))
+    {
+      current.prepend(action);
+      return;
+    }
+    current = current.next;
+  }
+
+  this.actions.append(action);
+}
+
 // Remove an action from trail using its reference
 Trail.prototype.removeAction = function (action) 
 {
@@ -79,38 +98,54 @@ Trail.prototype.removeAction = function (action)
     this.action.detach();
 }
 
-// aliases `in` and `out` represent the entrypoint and
-// output TrailNodes for this trail, which conceptually is
+// aliases `in` and `out` represent the input and
+// output TrailNodes for a trail, which conceptually is
 // done through the use of Port elements in Hyperknowledge
 Trail.prototype.in = function(from = null) {
   if (from)
   {
-    this.head.from = from;
+    this.actions.head.from = from;
   }
     
-  return this.head.from;
+  return this.actions.head.from;
 }
+
 Trail.prototype.out = function(to = null) {
   if (to)
   {
-    this.tail.to = to;
+    this.actions.tail.to = to;
   }
     
-  return this.tail.to;
+  return this.actions.tail.to;
+}
+
+Trail.prototype.size = function()
+{
+  if (this.actions.constructor === List)
+  {
+    return this.actions.size;
+  }
+  else if (Array.isArray(this.actions))
+  {
+    return this.actions.length;
+  }
 }
 
-Trail.prototype.join = function(delimiter) {
-    return this.toArray().join(delimiter)
+Trail.prototype.join = function(delimiter)
+{
+    return this.actions.toArray().join(delimiter)
 }
 
 // Update a given action in the trail
-Trail.prototype.update = function(action, newAction){
+Trail.prototype.update = function(action, newAction)
+{
     action.prepend(newAction)
     action.detach()
 }
 
 // Remove an action from the trail using its reference
-Trail.prototype.remove = function(action) {
+Trail.prototype.remove = function(action)
+{
     var action
     if(typeof(action) === 'string') {
         this.action = this.search(action)
@@ -130,12 +165,12 @@ Trail.prototype.remove = function(action) {
 // Get `num` actions (or the available ones) before `position`
 Trail.prototype.getPrev = function(position, num=1){
     //check if it is a valid position
-    if (position >= this.size || position <= 1 || this.size <= 1){
+    if (position >= this.actions.size || position <= 1 || this.actions.size <= 1){
         return;
     }
 
     // get actions
-    var action = this.toArray()[position]
+    var action = this.actions.toArray()[position]
     var resultSet = []
     while(action && action.prev){
         if (resultSet.length >= num) {
@@ -158,12 +193,12 @@ Trail.prototype.getPrev = function(position, num=1){
 // if a number is not given, 1 is assumed
 Trail.prototype.getNext = function(position, num=1){
     // check if it is a valid position
-    if (position >= this.size || position <= 1 || this.size <= 1){
+    if (position >= this.actions.size || position <= 1 || this.actions.size <= 1){
         return;
     }
 
     // get actions
-    var action = this.toArray()[position]
+    var action = this.actions.toArray()[position]
     var resultSet = []
     while(action && action.next){
         if (resultSet.length >= num) {
@@ -186,25 +221,25 @@ Trail.prototype.getNext = function(position, num=1){
 // -1 in case action is not found in the list
 Trail.prototype.getPositionOf = function(action){
     //search action by eventId
-    var array = this.toArray()
-    for (var i = 0; i < this.size; i++) {
+    var array = this.actions.toArray();
+    for (var i = 0; i < this.actions.size; i++) {
         if(array[i].event["eventId"] == action.event["eventId"]){
-            return i
+            return i;
         }
     }
-    return -1
+    return -1;
 }
 
 // Get an action at specified position
 // a position = 0 is equivalent to trail.head
 Trail.prototype.getActionAt = function(position) {
     //check if it is a valid position
-    if (position < 0 || position >= this.size ){
+    if (position < 0 || position >= this.actions.size ){
         return;
     }
 
     //return action by position in array
-    return this.toArray()[position]
+    return this.actions.toArray()[position]
 }
 
 // Search for action(s) either by an event identifier or by filters
@@ -223,19 +258,19 @@ Trail.prototype.search = function(eventId = null, filters){
     }
 
     // search actions by eventId
-    var array = this.toArray()
+    var array = this.actions.toArray();
     if (eventId){
-        for (var i = 0; i < this.size; i++) {
+        for (var i = 0; i < this.actions.size; i++) {
             if(array[i].event["eventId"] == eventId){
-                return array[i]
+                return array[i];
             }
         }
-        return
+        return;
     }
 
     // search actions by filters
     var resultSet = []
-    for (var i = 0; i < this.size; i++) {
+    for (var i = 0; i < this.actions.size; i++) {
         if((filters['from'] && filters['to']) && array[i].from == filters['from'] && array[i].to == filters['to']){
             resultSet.push(array[i])
         }
@@ -252,8 +287,7 @@ function loadActions(actions = null)
   // use array of actions if passed
   if(actions && Array.isArray(actions))
   {
-    this.actions = sort(actions);
-    
+    this.actions = new List(...sort(actions));
     return;
   }
 
@@ -261,40 +295,47 @@ function loadActions(actions = null)
   let actionIds = []
   for (let i in this.actions) 
   {
-    // create Action objects from parsed data
-    if (this.actions[i].hasOwnProperty("from") && 
+    // create Action object from hkb parsed data
+    if (this.actions[i] && this.actions[i].hasOwnProperty("from") && 
     this.actions[i].hasOwnProperty("to") && 
     this.actions[i].hasOwnProperty("agent") &&
     this.actions[i].hasOwnProperty("eventType"))
     {
       let from = new TrailNode(JSON.parse(this.actions[i].from).nodeId, JSON.parse(this.actions[i].from).nodeType, JSON.parse(this.actions[i].from).targetAnchor);
       let to = new TrailNode(JSON.parse(this.actions[i].to).nodeId, JSON.parse(this.actions[i].to).nodeType, JSON.parse(this.actions[i].to).targetAnchor);
-      let event = { "id": i, "type": this.actions[i].eventType, "properties": JSON.parse(this.actions[i].eventProperties), "timestamp": new Date(this.actions[i].hasTimestamp)}
-      let agent = this.actions[i].agent
+      let event = { "id": i, "type": this.actions[i].eventType, "properties": JSON.parse(this.actions[i].eventProperties), "timestamp": new Date(this.actions[i].hasTimestamp)};
+      let agent = this.actions[i].agent;
+
+      actionArray.push(new Action(from, to, event, agent));
+    }
+    // create Action object from json obj
+    else if (this.actions[i] && this.actions[i].hasOwnProperty("from") && 
+    this.actions[i].hasOwnProperty("to") && 
+    this.actions[i].hasOwnProperty("agent") &&
+    this.actions[i].hasOwnProperty("event"))
+    {
+      let from = new TrailNode(this.actions[i].from.nodeId, this.actions[i].from.nodeType, this.actions[i].from.targetAnchor);
+      let to = new TrailNode(this.actions[i].to.nodeId, this.actions[i].to.nodeType, this.actions[i].to.targetAnchor);
+      let event = { "id": this.actions[i].event.id, "type": this.actions[i].event.type, "properties": this.actions[i].event.properties, "timestamp": new Date(this.actions[i].event.timestamp)};
+      let agent = this.actions[i].agent;
 
       actionArray.push(new Action(from, to, event, agent));
     }
-    else if(this.actions[i].hasOwnProperty("hasTimestamp"))
+    else if(this.actions[i] && this.actions[i].hasOwnProperty("hasTimestamp"))
     {
       // all we got is event's id and timestamp
       actionIds.push(new Action(null, null, {"id": i, "timestamp": new Date(this.actions[i].hasTimestamp)}, null));
     }
   }
   
-  if (actionArray.length>0)
+  if (actionArray.length > 0)
   {
-    this.actions = sort(actionArray);
+    this.actions = new List(...sort(actionArray));
   }
-  else if (actionIds.length>0)
+  else if (actionIds.length > 0)
   {
-    actionIds = sort(actionIds);
-
-    for (let i in actionIds)
-    {
-      this.actions.push(actionIds[i].id);
-    }
+    this.actions = new List(...sort(actionIds));
   }
-  
 }
 
 function isValid(entity)
@@ -314,24 +355,51 @@ function isValid(entity)
 
 function sort(actions = null)
 {
-  if (actions && Array.isArray(actions) && actions[0] instanceof Object)
+  if (actions && Array.isArray(actions) && actions[0].event.timestamp.constructor === Date)
   {
     // sort and return object array based on timestamp
     return actions.sort(function(action1, action2)
     {
-      return new Date(action1.event['timestamp']) - new Date(action2.event['timestamp']);
+      return action1.event['timestamp'] - action2.event['timestamp'];
     });
   }
-  else if (actions && Array.isArray(actions) && this.actions[0] instanceof Action)
+  else if (actions && Array.isArray(actions) && actions[0].event.timestamp.constructor === String)
   {
     // sort Action array based on timestamp
     return actions.sort(function(action1, action2)
     {
-      return action1.event['timestamp'] - action2.event['timestamp'];
+      return new Date(action1.event['timestamp']) - new Date(action2.event['timestamp']);
     });
   }
 }
 
+Trail.prototype.toJSON = function ()
+{
+  if (this.actions.constructor === List && this.actions.head && (!this.actions.head.from && !this.actions.head.to && !this.actions.head.agent))
+  {
+    let actionArray = [];
+    let action = this.actions.head;
+    
+    while(action.next)
+    {
+      actionArray.push(action.id);
+      action = action.next;
+    }
+
+    this.actions = actionArray;
+  }
+
+  return {
+    id: this.id,
+    parent: this.parent,
+    properties: this.properties,
+    metaproperties: this.metaproperties,
+    interfaces: this.interfaces,
+    actions: this.actions,
+    type: this.type
+  }; 
+}
+
 Trail.prototype.serialize = function ()
 {
   return {
@@ -340,7 +408,7 @@ Trail.prototype.serialize = function ()
       properties: this.properties,
       metaproperties: this.metaproperties,
       interfaces: this.interfaces,
-      actions: this.actions,
+      actions: this.actions.toArray(),
       type: this.type
   };
 }
@@ -369,7 +437,7 @@ class TrailNode {
 class Action extends Item {
   constructor(from, to, event, agent) 
   {
-      super()
+      super();
       this.from = from;
       this.to = to;
       this.agent = agent;
@@ -405,7 +473,12 @@ class Action extends Item {
 
   toString() 
   {
-      return "[" + new Date(this.event['timestamp']).toISOString() + "] " + this.from + " -- " + this.event['eventId'] + " (by " + this.agent + ") --> " + this.to;
+      return JSON.stringify({ from: this.from, to: this.to, agent: this.agent, event: this.event, id: this.event.id });
+  }
+
+  toJSON() 
+  {
+      return { from: this.from, to: this.to, agent: this.agent, event: this.event, id: this.event.id };
   }
 }
 
@@ -413,8 +486,4 @@ Trail.type = Types.TRAIL;
 Trail.isValid = isValid;
 Trail.sort = sort;
 
-// Trail.Action = Action;
-// Trail.TrailNode = TrailNode;
-
 module.exports = Trail;
-

From 97b10dd9427a81a9cf4d4b56b421324cfbc337a9 Mon Sep 17 00:00:00 2001
From: Rafael Brandao <rmello@br.ibm.com>
Date: Wed, 22 Sep 2021 17:53:15 -0300
Subject: [PATCH 10/24] Improving Action load with linked list

---
 trail.js | 62 +++++++++++++++++++++++++++++---------------------------
 1 file changed, 32 insertions(+), 30 deletions(-)

diff --git a/trail.js b/trail.js
index aec2536..cc9687d 100644
--- a/trail.js
+++ b/trail.js
@@ -29,7 +29,7 @@ function Trail (id, actions, parent)
       this.properties = trail.properties || {};
       this.metaproperties = trail.metaproperties || {};
       this.interfaces = trail.interfaces || {};
-      this.actions = trail.actions || new List();
+      this.actions = trail.actions || {};
 
       if (this.actions && Object.keys(this.actions).length > 0) {
         loadActions.call(this); 
@@ -42,7 +42,7 @@ function Trail (id, actions, parent)
       this.interfaces = {};
       this.properties = {};
       this.metaproperties = {};
-      this.actions = actions || new List();
+      this.actions = actions || {};
 
     }
 
@@ -295,23 +295,10 @@ function loadActions(actions = null)
   let actionIds = []
   for (let i in this.actions) 
   {
-    // create Action object from hkb parsed data
+    // create Action object from json object
     if (this.actions[i] && this.actions[i].hasOwnProperty("from") && 
     this.actions[i].hasOwnProperty("to") && 
     this.actions[i].hasOwnProperty("agent") &&
-    this.actions[i].hasOwnProperty("eventType"))
-    {
-      let from = new TrailNode(JSON.parse(this.actions[i].from).nodeId, JSON.parse(this.actions[i].from).nodeType, JSON.parse(this.actions[i].from).targetAnchor);
-      let to = new TrailNode(JSON.parse(this.actions[i].to).nodeId, JSON.parse(this.actions[i].to).nodeType, JSON.parse(this.actions[i].to).targetAnchor);
-      let event = { "id": i, "type": this.actions[i].eventType, "properties": JSON.parse(this.actions[i].eventProperties), "timestamp": new Date(this.actions[i].hasTimestamp)};
-      let agent = this.actions[i].agent;
-
-      actionArray.push(new Action(from, to, event, agent));
-    }
-    // create Action object from json obj
-    else if (this.actions[i] && this.actions[i].hasOwnProperty("from") && 
-    this.actions[i].hasOwnProperty("to") && 
-    this.actions[i].hasOwnProperty("agent") &&
     this.actions[i].hasOwnProperty("event"))
     {
       let from = new TrailNode(this.actions[i].from.nodeId, this.actions[i].from.nodeType, this.actions[i].from.targetAnchor);
@@ -321,20 +308,26 @@ function loadActions(actions = null)
 
       actionArray.push(new Action(from, to, event, agent));
     }
-    else if(this.actions[i] && this.actions[i].hasOwnProperty("hasTimestamp"))
+    else if(this.actions[i] && this.actions[i].hasOwnProperty("event") && this.actions[i].event.hasOwnProperty("timestamp"))
+    {
+      // we got event's id and timestamp
+      actionArray.push(new Action(null, null, {"id": i, "timestamp": new Date(this.actions[i].event.timestamp)}, null));
+    }
+    else 
     {
-      // all we got is event's id and timestamp
-      actionIds.push(new Action(null, null, {"id": i, "timestamp": new Date(this.actions[i].hasTimestamp)}, null));
+       // all we got is event's id
+       actionIds.push(i);
     }
   }
   
+  // sort action items before creating list
   if (actionArray.length > 0)
   {
     this.actions = new List(...sort(actionArray));
   }
   else if (actionIds.length > 0)
   {
-    this.actions = new List(...sort(actionIds));
+    this.actions = actionIds;
   }
 }
 
@@ -375,18 +368,27 @@ function sort(actions = null)
 
 Trail.prototype.toJSON = function ()
 {
-  if (this.actions.constructor === List && this.actions.head && (!this.actions.head.from && !this.actions.head.to && !this.actions.head.agent))
+  let actionArray = [];
+
+  if (this.actions.constructor === List)
   {
-    let actionArray = [];
-    let action = this.actions.head;
-    
-    while(action.next)
+    //in case we have only action ids and timestamps
+    if(this.actions.head && (!this.actions.head.from && !this.actions.head.to && !this.actions.head.agent))
     {
-      actionArray.push(action.id);
-      action = action.next;
+      let action = this.actions.head;
+      
+      while(action.next)
+      {
+        actionArray.push(action.id);
+        action = action.next;
+      }
     }
-
-    this.actions = actionArray;
+    else {
+      actionArray = this.actions.toArray();
+    }
+  }
+  else{
+    actionArray = this.actions;
   }
 
   return {
@@ -395,7 +397,7 @@ Trail.prototype.toJSON = function ()
     properties: this.properties,
     metaproperties: this.metaproperties,
     interfaces: this.interfaces,
-    actions: this.actions,
+    actions: actionArray,
     type: this.type
   }; 
 }

From 8bf4efa44d40c899d3b811ad9df8d323f3c176df Mon Sep 17 00:00:00 2001
From: Rafael Brandao <rmello@br.ibm.com>
Date: Fri, 24 Sep 2021 10:18:52 -0300
Subject: [PATCH 11/24] Improving action class and its loading and sorting

---
 trail.js | 83 ++++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 57 insertions(+), 26 deletions(-)

diff --git a/trail.js b/trail.js
index cc9687d..cbe6dc2 100644
--- a/trail.js
+++ b/trail.js
@@ -12,6 +12,7 @@ const {List, Item}    = require('linked-list');
 // const shortid   = require('shortid');
 const Types     = require('./types');
 const HKEntity  = require('./hkentity');
+const e = require('express');
 // const Connector = require('./connector');
 // const Link      = require('./link');
 // const RoleTypes = require('./roletypes');
@@ -29,10 +30,10 @@ function Trail (id, actions, parent)
       this.properties = trail.properties || {};
       this.metaproperties = trail.metaproperties || {};
       this.interfaces = trail.interfaces || {};
-      this.actions = trail.actions || {};
+      this.actions = trail.actions || new List();
 
       if (this.actions && Object.keys(this.actions).length > 0) {
-        loadActions.call(this); 
+        this.loadActions(); 
       }
     }
     else
@@ -42,7 +43,7 @@ function Trail (id, actions, parent)
       this.interfaces = {};
       this.properties = {};
       this.metaproperties = {};
-      this.actions = actions || {};
+      this.actions = actions || new List();
 
     }
 
@@ -70,13 +71,12 @@ Trail.prototype.addAction = function (action)
   {
     if (new Date(current.event['timestamp']) - new Date(action.event['timestamp']))
     {
-      current.prepend(action);
-      return;
+      return current.prepend(action);
     }
     current = current.next;
   }
 
-  this.actions.append(action);
+  return this.actions.append(action);
 }
 
 // Remove an action from trail using its reference
@@ -98,6 +98,18 @@ Trail.prototype.removeAction = function (action)
     this.action.detach();
 }
 
+// `append` and `prepend` operations are 
+// handled by our linked list structure
+Trail.prototype.append = function(action)
+{
+  return this.actions.append(action);
+}
+
+Trail.prototype.prepend = function(action)
+{
+  return this.actions.prepend(action);
+}
+
 // aliases `in` and `out` represent the input and
 // output TrailNodes for a trail, which conceptually is
 // done through the use of Port elements in Hyperknowledge
@@ -223,7 +235,7 @@ Trail.prototype.getPositionOf = function(action){
     //search action by eventId
     var array = this.actions.toArray();
     for (var i = 0; i < this.actions.size; i++) {
-        if(array[i].event["eventId"] == action.event["eventId"]){
+        if(array[i].event["id"] == action.event["id"]){
             return i;
         }
     }
@@ -261,7 +273,7 @@ Trail.prototype.search = function(eventId = null, filters){
     var array = this.actions.toArray();
     if (eventId){
         for (var i = 0; i < this.actions.size; i++) {
-            if(array[i].event["eventId"] == eventId){
+            if(array[i].event["id"] == eventId){
                 return array[i];
             }
         }
@@ -281,14 +293,20 @@ Trail.prototype.search = function(eventId = null, filters){
     return resultSet
 }
 
-function loadActions(actions = null)
+Trail.prototype.loadActions = function (actions = null)
 {
 
   // use array of actions if passed
   if(actions && Array.isArray(actions))
   {
-    this.actions = new List(...sort(actions));
-    return;
+    if(actions[0].event.timestamp)
+    {
+      this.actions = new List(...sort(actions));
+    }
+    else {
+      this.actions = new List(...actions);
+    }
+    return this.actions;
   }
 
   let actionArray = []
@@ -306,12 +324,12 @@ function loadActions(actions = null)
       let event = { "id": this.actions[i].event.id, "type": this.actions[i].event.type, "properties": this.actions[i].event.properties, "timestamp": new Date(this.actions[i].event.timestamp)};
       let agent = this.actions[i].agent;
 
-      actionArray.push(new Action(from, to, event, agent));
+      actionArray.push(new Action({from, to, event, agent}));
     }
     else if(this.actions[i] && this.actions[i].hasOwnProperty("event") && this.actions[i].event.hasOwnProperty("timestamp"))
     {
       // we got event's id and timestamp
-      actionArray.push(new Action(null, null, {"id": i, "timestamp": new Date(this.actions[i].event.timestamp)}, null));
+      actionArray.push(new Action({event: {"id": i, "timestamp": new Date(this.actions[i].event.timestamp)}}));
     }
     else 
     {
@@ -356,7 +374,7 @@ function sort(actions = null)
       return action1.event['timestamp'] - action2.event['timestamp'];
     });
   }
-  else if (actions && Array.isArray(actions) && actions[0].event.timestamp.constructor === String)
+  else if (actions && Array.isArray(actions) && (actions[0].event.timestamp.constructor === String || actions[0].event.timestamp.constructor === Number))
   {
     // sort Action array based on timestamp
     return actions.sort(function(action1, action2)
@@ -376,8 +394,8 @@ Trail.prototype.toJSON = function ()
     if(this.actions.head && (!this.actions.head.from && !this.actions.head.to && !this.actions.head.agent))
     {
       let action = this.actions.head;
-      
-      while(action.next)
+
+      while(action)
       {
         actionArray.push(action.id);
         action = action.next;
@@ -387,7 +405,8 @@ Trail.prototype.toJSON = function ()
       actionArray = this.actions.toArray();
     }
   }
-  else{
+  else if (Array.isArray(this.actions))
+  {
     actionArray = this.actions;
   }
 
@@ -437,7 +456,7 @@ class TrailNode {
 // nodes (along with their respective target anchors), 
 // the related event and an agent (user, system or content).
 class Action extends Item {
-  constructor(from, to, event, agent) 
+  constructor({from = null, to = null, event = {}, agent = null} = {}) 
   {
       super();
       this.from = from;
@@ -445,16 +464,12 @@ class Action extends Item {
       this.agent = agent;
       this.event = event;
 
-      if(!this.event)
-      {
-        return
-      }
 
       // create timestamp if needed
-      if(!this.event['timestamp'])
-      {
-          this.event['timestamp'] = new Date().getTime();
-      }
+      // if(!this.event['timestamp'])
+      // {
+      //     this.event['timestamp'] = new Date().getTime();
+      // }
 
       // get event id or create a new one
       if(!this.event['id'] || this.event['id'] == '') 
@@ -475,17 +490,33 @@ class Action extends Item {
 
   toString() 
   {
+    if(this.from && this.to && this.agent && this.event && this.event.id )
+    {
       return JSON.stringify({ from: this.from, to: this.to, agent: this.agent, event: this.event, id: this.event.id });
+    }
+    else 
+    {
+      return this.event.id;
+    }
   }
 
   toJSON() 
   {
+    if(this.from && this.to && this.agent && this.event && this.event.id )
+    {
       return { from: this.from, to: this.to, agent: this.agent, event: this.event, id: this.event.id };
+    }
+    else 
+    {
+      return this.event.id;
+    }
   }
 }
 
 Trail.type = Types.TRAIL;
 Trail.isValid = isValid;
 Trail.sort = sort;
+Trail.Action = Action;
+Trail.TrailNode = TrailNode;
 
 module.exports = Trail;

From 07c724cdc8cf36026befda1059c4f2ee6de930c4 Mon Sep 17 00:00:00 2001
From: Rafael Brandao <rmello@br.ibm.com>
Date: Sat, 25 Sep 2021 19:55:30 -0300
Subject: [PATCH 12/24] Removing unused require

---
 trail.js | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/trail.js b/trail.js
index cbe6dc2..cd95480 100644
--- a/trail.js
+++ b/trail.js
@@ -6,16 +6,10 @@
 'use strict'
 
 const {List, Item}    = require('linked-list');
-// const List      = Linked.List;
-// const Item      = Linked.Item;
 
 // const shortid   = require('shortid');
 const Types     = require('./types');
 const HKEntity  = require('./hkentity');
-const e = require('express');
-// const Connector = require('./connector');
-// const Link      = require('./link');
-// const RoleTypes = require('./roletypes');
 
 
 function Trail (id, actions, parent)

From 8892edf49e764cd83f40966719fa65652cd3ca89 Mon Sep 17 00:00:00 2001
From: Gabriela Pinheiro <gabrielapc@id.uff.br>
Date: Wed, 24 Nov 2021 13:09:42 -0300
Subject: [PATCH 13/24] Added actions to hkgraph

---
 hkgraph.js | 24 ++++++++++++++++++++----
 index.js   |  1 +
 trail.js   |  7 ++++++-
 types.js   |  1 +
 4 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/hkgraph.js b/hkgraph.js
index 463b4f1..f5dc1cd 100644
--- a/hkgraph.js
+++ b/hkgraph.js
@@ -9,10 +9,11 @@ const Connector 	= require("./connector");
 const Context 		= require("./context");
 const Link 			= require("./link");
 const Node 			= require("./node");
-const Reference 	= require("./reference");
+const Reference 	= require("./reference"); 
 const Trail 		= require("./trail");
 const Types 		= require("./types");
 const shortid 		= require('shortid');
+const { Action }    = require("./trail");
 
 function HKGraph()
 {
@@ -22,6 +23,7 @@ function HKGraph()
 	this.connectors = {};
 	this.refs = {};
 	this.trails = {};
+	this.actions = {};
 
 	// Auxiliar maps
 	this.bindsMap = {};
@@ -43,7 +45,8 @@ HKGraph.prototype.hasId = function(id)
 		this.links.hasOwnProperty(id) ||
 		this.connectors.hasOwnProperty(id) ||
 		this.refs.hasOwnProperty(id) ||
-		this.trails.hasOwnProperty(id);
+		this.trails.hasOwnProperty(id) ||
+		this.actions.hasOwnProperty(id);
 };
 
 
@@ -72,7 +75,7 @@ HKGraph.prototype.setEntity = function(entity)
 		oldEntity.className = entity.className;
     }
 
-    if(entity.type === Types.NODE || entity.type === Types.TRAIL || entity.type === Types.REFERENCE || entity.type === Types.CONTEXT)
+    if(entity.type === Types.NODE || entity.type === Types.TRAIL || entity.type === Types.REFERENCE || entity.type === Types.CONTEXT || entity.type === Types.ACTION)
     {
         
         oldEntity.interfaces = entity.interfaces;
@@ -190,6 +193,15 @@ HKGraph.prototype.addEntity = function(entity)
                 }
                 break;
             }
+			case Types.ACTION:
+			{
+				if(entity instanceof Trail.Action)
+				{
+					newEntity = entity;
+					this.actions[entity.id] = newEntity;
+				}
+				break;
+			}
 			case Types.LINK:
             {
                 if (Link.isValid(entity))
@@ -350,6 +362,10 @@ HKGraph.prototype.removeEntity = function(id)
 				delete this.compositeNodeMap[entity.id];
                 break;
             }
+			case Action.type:
+			{
+				delete this.actions[id];
+			}
 		}
 
         if(this.orphans.hasOwnProperty(entity.parent))
@@ -480,7 +496,7 @@ HKGraph.prototype.getEntity = function(id)
 		c.id = null;
 		return c;
 	}
-	return this.nodes[id] || this.contexts[id] || this.links[id] || this.connectors[id] || this.refs[id] || this.trails[id] || null;
+	return this.nodes[id] || this.contexts[id] || this.links[id] || this.connectors[id] || this.refs[id] || this.trails[id] || this.actions[id] || null;
 };
 
 HKGraph.prototype.getEntities = function()
diff --git a/index.js b/index.js
index 6d084e4..bedb372 100644
--- a/index.js
+++ b/index.js
@@ -26,6 +26,7 @@ exports.CONNECTOR_TYPE = Types.CONNECTOR;
 exports.BIND_TYPE      = Types.BIND;
 exports.INTERFACE      = Types.INTERFACE;
 exports.TRAIL_TYPE     = Types.TRAIL;
+exports.ACTION_TYPE    = Types.ACTION;
 
 const RolesTypes       = require("./roletypes");
 
diff --git a/trail.js b/trail.js
index cd95480..05da606 100644
--- a/trail.js
+++ b/trail.js
@@ -325,6 +325,11 @@ Trail.prototype.loadActions = function (actions = null)
       // we got event's id and timestamp
       actionArray.push(new Action({event: {"id": i, "timestamp": new Date(this.actions[i].event.timestamp)}}));
     }
+    else if(Array.isArray(this.actions))
+    {
+      // all we got is an Array with the event's id
+      actionIds.push(this.actions[i]);
+    }
     else 
     {
        // all we got is event's id
@@ -457,7 +462,7 @@ class Action extends Item {
       this.to = to;
       this.agent = agent;
       this.event = event;
-
+      this.type = Types.ACTION;
 
       // create timestamp if needed
       // if(!this.event['timestamp'])
diff --git a/types.js b/types.js
index 1f87e69..8c75ec6 100644
--- a/types.js
+++ b/types.js
@@ -14,6 +14,7 @@ exports.REFERENCE = 'ref';
 exports.INTERFACE = 'interface';
 exports.BIND      = 'bind';
 exports.TRAIL     = 'trail';
+exports.ACTION    = 'action';
 
 exports.isValidType = function (type)
 {

From f1af0da1bcf6dc025be93e15e65e1db54895766d Mon Sep 17 00:00:00 2001
From: Gabriela Pinheiro <gabrielapc@id.uff.br>
Date: Mon, 13 Dec 2021 15:35:10 -0300
Subject: [PATCH 14/24] this.actions.toArray is not a function bugfix

---
 trail.js | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/trail.js b/trail.js
index 05da606..6d15191 100644
--- a/trail.js
+++ b/trail.js
@@ -422,13 +422,23 @@ Trail.prototype.toJSON = function ()
 
 Trail.prototype.serialize = function ()
 {
+  let actions;
+  if(this.actions instanceof Array)
+  {
+    actions = this.actions;
+  }
+  else
+  {
+    actions = this.actions.toArray();
+  }
+
   return {
       id: this.id,
       parent: this.parent,
       properties: this.properties,
       metaproperties: this.metaproperties,
       interfaces: this.interfaces,
-      actions: this.actions.toArray(),
+      actions: actions,
       type: this.type
   };
 }

From ba8161d6a9d56166cc03275c6ab1427556229b82 Mon Sep 17 00:00:00 2001
From: Gabriela Pinheiro <gabrielapc@id.uff.br>
Date: Wed, 19 Jan 2022 18:00:29 -0300
Subject: [PATCH 15/24] Bugfix Trail.out not working with only one action

---
 trail.js | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/trail.js b/trail.js
index 6d15191..01ec7cb 100644
--- a/trail.js
+++ b/trail.js
@@ -117,12 +117,22 @@ Trail.prototype.in = function(from = null) {
 }
 
 Trail.prototype.out = function(to = null) {
+  if(this.actions.tail)
+  {
+    if (to)
+    {
+      this.actions.tail.to = to;
+    }
+      
+    return this.actions.tail.to;
+  }
+
   if (to)
   {
-    this.actions.tail.to = to;
+    this.actions.head.to = to;
   }
     
-  return this.actions.tail.to;
+  return this.actions.head.to;
 }
 
 Trail.prototype.size = function()

From 43823a4c55391b6e03f6f98d6fc948fea2ee7c9c Mon Sep 17 00:00:00 2001
From: Gabriela Pinheiro <gpinheiro@ibm.com>
Date: Tue, 28 Jun 2022 17:50:49 -0300
Subject: [PATCH 16/24] Merge bugfix

---
 src/hkgraph.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/hkgraph.js b/src/hkgraph.js
index 1e8e20f..88ab655 100644
--- a/src/hkgraph.js
+++ b/src/hkgraph.js
@@ -86,7 +86,7 @@ class HKGraph
       oldEntity.className = entity.className;
     }
 
-    if (entity.type === HKTypes.NODE || entity.type === Types.TRAIL || entity.type === HKTypes.REFERENCE || entity.type === HKTypes.CONTEXT || entity.type === HKTypes.VIRTUAL_NODE || entity.type === HKTypes.VIRTUAL_CONTEXT || entity.type === Types.ACTION)
+    if (entity.type === HKTypes.NODE || entity.type === HKTypes.TRAIL || entity.type === HKTypes.REFERENCE || entity.type === HKTypes.CONTEXT || entity.type === HKTypes.VIRTUAL_NODE || entity.type === HKTypes.VIRTUAL_CONTEXT || entity.type === HKTypes.ACTION)
     {
       oldEntity.interfaces = entity.interfaces;
     }

From 32c887096de2a8cee1e48273378e2551baf23212 Mon Sep 17 00:00:00 2001
From: Elton Soares <eltonfss@gmail.com>
Date: Wed, 29 Jun 2022 18:30:23 -0300
Subject: [PATCH 17/24] Identation fix

---
 src/types.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/types.js b/src/types.js
index e1f6a95..897ae77 100644
--- a/src/types.js
+++ b/src/types.js
@@ -13,7 +13,7 @@ exports.REFERENCE = 'ref';
 exports.INTERFACE = 'interface';
 exports.BIND = 'bind';
 exports.TRAIL = 'trail';
-exports.ACTION    = 'action';
+exports.ACTION = 'action';
 exports.VIRTUAL_NODE = 'virtualnode';
 exports.VIRTUAL_CONTEXT = 'virtualcontext';
 exports.VIRTUAL_LINK = 'virtuallink';

From 66c0f805e3a4b9e9687db75dbe1bc6b4e9dd305a Mon Sep 17 00:00:00 2001
From: Gabriela Pinheiro <gpinheiro@ibm.com>
Date: Thu, 30 Jun 2022 16:59:03 -0300
Subject: [PATCH 18/24] Added linked-list to HKLib

---
 package.json                 |   2 +-
 src/linked-list/index.cjs    | 290 +++++++++++++++++++++++++++
 src/linked-list/index.d.ts   |  29 +++
 src/linked-list/license      |  22 +++
 src/linked-list/package.json | 115 +++++++++++
 src/linked-list/readme.md    | 368 +++++++++++++++++++++++++++++++++++
 6 files changed, 825 insertions(+), 1 deletion(-)
 create mode 100644 src/linked-list/index.cjs
 create mode 100644 src/linked-list/index.d.ts
 create mode 100644 src/linked-list/license
 create mode 100644 src/linked-list/package.json
 create mode 100644 src/linked-list/readme.md

diff --git a/package.json b/package.json
index 9e22a0c..3820d7c 100644
--- a/package.json
+++ b/package.json
@@ -53,7 +53,7 @@
     "request": "^2.88.0",
     "request-promise-native": "^1.0.8",
     "shortid": "^2.2.14",
-    "linked-list": "git+ssh://git@github.ibm.com:keg-core/linked-list.git"
+    "linked-list": "file:src/linked-list"
   },
   "license": "MIT",
   "repository": {
diff --git a/src/linked-list/index.cjs b/src/linked-list/index.cjs
new file mode 100644
index 0000000..5dc2d37
--- /dev/null
+++ b/src/linked-list/index.cjs
@@ -0,0 +1,290 @@
+// Creates a new `Iterator` for looping over the `List`.
+class Iterator {
+  constructor(item) {
+    this.item = item
+  }
+
+  // Move the `Iterator` to the next item.
+  next() {
+    this.value = this.item
+    this.done = !this.item
+    this.item = this.item ? this.item.next : undefined
+    return this
+  }
+}
+
+// Creates a new `Item`:
+// An item is a bit like DOM node: It knows only about its “parent” (`list`),
+// the item before it (`prev`), and the item after it (`next`).
+class Item {
+  // Prepends the given item *before* the item operated on.
+  prepend(item) {
+    var list = this.list
+
+    if (!item || !item.append || !item.prepend || !item.detach) {
+      throw new Error(
+        'An argument without append, prepend, or detach methods was given to `Item#prepend`.'
+      )
+    }
+
+    // If self is detached, return false.
+    if (!list) {
+      return false
+    }
+
+    // Detach the prependee.
+    item.detach()
+
+    // If self has a previous item...
+    if (this.prev) {
+      item.prev = this.prev
+      this.prev.next = item
+    }
+
+    // Connect the prependee.
+    item.next = this
+    item.list = list
+
+    // Set the previous item of self to the prependee.
+    this.prev = item
+
+    // If self is the first item in the parent list, link the lists first item to
+    // the prependee.
+    if (this === list.head) {
+      list.head = item
+    }
+
+    // If the the parent list has no last item, link the lists last item to self.
+    if (!list.tail) {
+      list.tail = this
+    }
+
+    list.size++
+
+    return item
+  }
+
+  // Appends the given item *after* the item operated on.
+  append(item) {
+    var list = this.list
+
+    if (!item || !item.append || !item.prepend || !item.detach) {
+      throw new Error(
+        'An argument without append, prepend, or detach methods was given to `Item#append`.'
+      )
+    }
+
+    if (!list) {
+      return false
+    }
+
+    // Detach the appendee.
+    item.detach()
+
+    // If self has a next item…
+    if (this.next) {
+      item.next = this.next
+      this.next.prev = item
+    }
+
+    // Connect the appendee.
+    item.prev = this
+    item.list = list
+
+    // Set the next item of self to the appendee.
+    this.next = item
+
+    // If the the parent list has no last item or if self is the parent lists last
+    // item, link the lists last item to the appendee.
+    if (this === list.tail || !list.tail) {
+      list.tail = item
+    }
+
+    list.size++
+
+    return item
+  }
+
+  // Detaches the item operated on from its parent list.
+  detach() {
+    var list = this.list
+
+    if (!list) {
+      return this
+    }
+
+    // If self is the last item in the parent list, link the lists last item to
+    // the previous item.
+    if (list.tail === this) {
+      list.tail = this.prev
+    }
+
+    // If self is the first item in the parent list, link the lists first item to
+    // the next item.
+    if (list.head === this) {
+      list.head = this.next
+    }
+
+    // If both the last and first items in the parent list are the same, remove
+    // the link to the last item.
+    if (list.tail === list.head) {
+      list.tail = null
+    }
+
+    // If a previous item exists, link its next item to selfs next item.
+    if (this.prev) {
+      this.prev.next = this.next
+    }
+
+    // If a next item exists, link its previous item to selfs previous item.
+    if (this.next) {
+      this.next.prev = this.prev
+    }
+
+    // Remove links from self to both the next and previous items, and to the
+    // parent list.
+    this.prev = this.next = this.list = null
+
+    list.size--
+
+    return this
+  }
+}
+
+Item.prototype.next = Item.prototype.prev = Item.prototype.list = null
+
+// Creates a new List: A linked list is a bit like an Array, but knows nothing
+// about how many items are in it, and knows only about its first (`head`) and
+// last (`tail`) items.
+// Each item (e.g. `head`, `tail`, &c.) knows which item comes before or after
+// it (its more like the implementation of the DOM in JavaScript).
+class List {
+  // Creates a new list from the arguments (each a list item) passed in.
+  static of(...items) {
+    return appendAll(new this(), items)
+  }
+
+  // Creates a new list from the given array-like object (each a list item) passed
+  // in.
+  static from(items) {
+    return appendAll(new this(), items)
+  }
+
+  constructor(...items) {
+    appendAll(this, items)
+  }
+
+  // Returns the list’s items as an array.
+  // This does *not* detach the items.
+  toArray() {
+    var item = this.head
+    var result = []
+
+    while (item) {
+      result.push(item)
+      item = item.next
+    }
+
+    return result
+  }
+
+  // Prepends the given item to the list.
+  // `item` will be the new first item (`head`).
+  prepend(item) {
+    if (!item) {
+      return false
+    }
+
+    if (!item.append || !item.prepend || !item.detach) {
+      throw new Error(
+        'An argument without append, prepend, or detach methods was given to `List#prepend`.'
+      )
+    }
+
+    if (this.head) {
+      return this.head.prepend(item)
+    }
+
+    item.detach()
+    item.list = this
+    this.head = item
+    this.size++
+
+    return item
+  }
+
+  // Appends the given item to the list.
+  // `item` will be the new last item (`tail`) if the list had a first item, and
+  // its first item (`head`) otherwise.
+  append(item) {
+    if (!item) {
+      return false
+    }
+
+    if (!item.append || !item.prepend || !item.detach) {
+      throw new Error(
+        'An argument without append, prepend, or detach methods was given to `List#append`.'
+      )
+    }
+
+    // If self has a last item, defer appending to the last items append method,
+    // and return the result.
+    if (this.tail) {
+      return this.tail.append(item)
+    }
+
+    // If self has a first item, defer appending to the first items append method,
+    // and return the result.
+    if (this.head) {
+      return this.head.append(item)
+    }
+
+    // …otherwise, there is no `tail` or `head` item yet.
+    item.detach()
+    item.list = this
+    this.head = item
+    this.size++
+
+    return item
+  }
+
+  // Creates an iterator from the list.
+  [Symbol.iterator]() {
+    return new Iterator(this.head)
+  }
+}
+
+List.prototype.size = 0
+List.prototype.tail = List.prototype.head = null
+
+// Creates a new list from the items passed in.
+function appendAll(list, items) {
+  var index
+  var item
+  var iterator
+
+  if (!items) {
+    return list
+  }
+
+  if (items[Symbol.iterator]) {
+    iterator = items[Symbol.iterator]()
+    item = {}
+
+    while (!item.done) {
+      item = iterator.next()
+      list.append(item && item.value)
+    }
+  } else {
+    index = -1
+
+    while (++index < items.length) {
+      list.append(items[index])
+    }
+  }
+
+  return list
+}
+
+module.exports.Item = Item;
+module.exports.List = List;
\ No newline at end of file
diff --git a/src/linked-list/index.d.ts b/src/linked-list/index.d.ts
new file mode 100644
index 0000000..4cfe851
--- /dev/null
+++ b/src/linked-list/index.d.ts
@@ -0,0 +1,29 @@
+export namespace List{
+  export class Item {
+    prev: this
+    next: this
+    list: List<this>
+  
+    detach(): this
+    prepend<T extends this>(item: T): T
+    append<T extends this>(item: T): T
+  }
+}
+export class List<T extends List.Item> implements Iterable<T> {
+  static of<T extends List.Item>(...items: T[]): List<T>
+  static from<T extends List.Item>(items: Iterable<T>): List<T>
+
+  head: T | null
+  tail: T | null
+  size: number
+
+  constructor(...items: T[])
+  toArray(): T[]
+  prepend<T>(item: T): T
+  append<T>(item: T): T
+  [Symbol.iterator](): Iterator<T>
+}
+
+export type  Item = List.Item;
+
+
diff --git a/src/linked-list/license b/src/linked-list/license
new file mode 100644
index 0000000..0c06d5b
--- /dev/null
+++ b/src/linked-list/license
@@ -0,0 +1,22 @@
+(The MIT License)
+
+Copyright (c) 2014 Titus Wormer <tituswormer@gmail.com>
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+'Software'), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/src/linked-list/package.json b/src/linked-list/package.json
new file mode 100644
index 0000000..8a80e09
--- /dev/null
+++ b/src/linked-list/package.json
@@ -0,0 +1,115 @@
+{
+  "_from": "git+ssh://git@github.ibm.com:keg-core/linked-list.git",
+  "_id": "linked-list@3.0.1",
+  "_inBundle": false,
+  "_integrity": "",
+  "_location": "/linked-list",
+  "_phantomChildren": {},
+  "_requested": {
+    "type": "git",
+    "raw": "linked-list@git+ssh://git@github.ibm.com:keg-core/linked-list.git",
+    "name": "linked-list",
+    "escapedName": "linked-list",
+    "rawSpec": "git+ssh://git@github.ibm.com:keg-core/linked-list.git",
+    "saveSpec": "git+ssh://git@github.ibm.com:keg-core/linked-list.git",
+    "fetchSpec": "git@github.ibm.com:keg-core/linked-list.git",
+    "gitCommittish": null
+  },
+  "_requiredBy": [
+    "/"
+  ],
+  "_resolved": "git+ssh://git@github.ibm.com:keg-core/linked-list.git#778981762dbdcbf5f10b031345ce9756c29e0915",
+  "_spec": "linked-list@git+ssh://git@github.ibm.com:keg-core/linked-list.git",
+  "_where": "/Users/gabrielapinheiro/ghe/keg/hklib",
+  "author": {
+    "name": "Titus Wormer",
+    "email": "tituswormer@gmail.com",
+    "url": "https://wooorm.com"
+  },
+  "bugs": {
+    "url": "https://github.com/wooorm/linked-list/issues"
+  },
+  "bundleDependencies": false,
+  "contributors": [
+    {
+      "name": "Titus Wormer",
+      "email": "tituswormer@gmail.com",
+      "url": "https://wooorm.com"
+    },
+    {
+      "name": "Blake Embrey",
+      "email": "hello@blakeembrey.com"
+    },
+    {
+      "name": "Regev Brody",
+      "email": "regevbr@gmail.com"
+    }
+  ],
+  "deprecated": false,
+  "description": "Minimalistic linked lists",
+  "devDependencies": {
+    "@types/tape": "^4.0.0",
+    "c8": "^7.0.0",
+    "prettier": "^2.0.0",
+    "remark-cli": "^9.0.0",
+    "remark-preset-wooorm": "^8.0.0",
+    "tape": "^5.0.0",
+    "xo": "^0.38.0"
+  },
+  "files": [
+    "index.cjs",
+    "index.d.ts"
+  ],
+  "funding": {
+    "type": "github",
+    "url": "https://github.com/sponsors/wooorm"
+  },
+  "homepage": "https://github.com/wooorm/linked-list#readme",
+  "keywords": [
+    "double",
+    "linked",
+    "list"
+  ],
+  "license": "MIT",
+  "main": "index.cjs",
+  "name": "linked-list",
+  "prettier": {
+    "tabWidth": 2,
+    "useTabs": false,
+    "singleQuote": true,
+    "bracketSpacing": false,
+    "semi": false,
+    "trailingComma": "none"
+  },
+  "remarkConfig": {
+    "plugins": [
+      "preset-wooorm"
+    ]
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/wooorm/linked-list.git"
+  },
+  "scripts": {
+    "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
+    "test": "npm run format && npm run test-coverage",
+    "test-api": "node test.js",
+    "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node test.js"
+  },
+  "sideEffects": false,
+  "type": "module",
+  "types": "index.d.ts",
+  "version": "3.0.1",
+  "xo": {
+    "prettier": true,
+    "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off",
+      "no-multi-assign": "off"
+    },
+    "ignores": [
+      "*.ts",
+      "linked-list.js"
+    ]
+  }
+}
diff --git a/src/linked-list/readme.md b/src/linked-list/readme.md
new file mode 100644
index 0000000..20321ea
--- /dev/null
+++ b/src/linked-list/readme.md
@@ -0,0 +1,368 @@
+# linked-list
+
+[![Build][build-badge]][build]
+[![Coverage][coverage-badge]][coverage]
+[![Downloads][downloads-badge]][downloads]
+[![Size][size-badge]][size]
+
+Small double [linked list][wiki].
+
+## Install
+
+This package is ESM only: Node 12+ is needed to use it and it must be `import`ed
+instead of `require`d.
+
+<b>Edit: We forked this opensource lib and modified it so we could use it with `require`, since some HK images (e.g. KES) are still based on Node 12 and all of them use required instead of import.</b>
+
+[npm][]:
+
+```sh
+npm install linked-list
+```
+
+## Use
+
+```js
+import {List, Item} from 'linked-list'
+
+var item1 = new Item()
+var item2 = new Item()
+var item3 = new Item()
+var list = new List(item1, item2, item3)
+
+list.head // => item1
+list.head.next // => item2
+list.head.next.next // => item3
+list.head.next.prev // => item1
+list.tail // => item3
+list.tail.next // => `null`
+```
+
+Subclassing:
+
+```js
+import {List, Item} from 'linked-list'
+
+class Tokens extends List {
+  join(delimiter) {
+    return this.toArray().join(delimiter)
+  }
+}
+
+class Token extends Item {
+  constructor(value) {
+    super()
+    this.value = value
+  }
+
+  toString() {
+    return this.value
+  }
+}
+
+var dogs = new Token('dogs')
+var and = new Token('&')
+var cats = new Token('cats')
+var tokens = new Tokens(dogs, and, cats)
+
+console.log(tokens.join(' ')) // => 'dogs & cats'
+
+and.prepend(cats)
+and.append(dogs)
+
+console.log(tokens.join(' ') + '!') // => 'cats & dogs!'
+```
+
+## API
+
+This package exports the following identifiers: `List`, `Item`.
+There is no default export.
+
+### `List([items…])`
+
+```js
+new List()
+new List(new Item(), new Item())
+```
+
+Create a new linked list.
+
+#### `List.from([items])`
+
+```js
+List.from()
+List.from([])
+List.from([new Item(), new Item()])
+```
+
+Create a new `this` and adds the given array of items.
+Ignores `null` or `undefined` values.
+Throws an error when a given item has no `detach`, `append`, or `prepend`
+methods.
+
+#### `List.of([items…])`
+
+```js
+List.of()
+List.of(new Item(), new Item())
+```
+
+Creates a new linked list from the given arguments.
+Defers to `List.from`.
+
+#### `List#append(item)`
+
+```js
+var list = new List()
+var item = new Item()
+
+list.head === null // => true
+item.list === null // => true
+
+list.append(item)
+
+list.head === item // => true
+item.list === list // => true
+```
+
+Appends an item to a list.
+Throws an error when the given item has no `detach`, `append`, or `prepend`
+methods.
+Returns the given item.
+
+#### `List#prepend(item)`
+
+```js
+var list = new List()
+var item = new Item()
+
+list.prepend(item)
+```
+
+Prepends an item to a list.
+Throws an error when the given item has no `detach`, `append`, or `prepend`
+methods.
+Returns the given item.
+
+#### `List#toArray()`
+
+```js
+var item1 = new Item()
+var item2 = new Item()
+var list = new List(item1, item2)
+var array = list.toArray()
+
+array[0] === item1 // => true
+array[1] === item2 // => true
+array[0].next === item2 // => true
+array[1].prev === item1 // => true
+```
+
+Returns the items in the list in an array.
+
+#### `List#head`
+
+```js
+var item = new Item()
+var list = new List(item)
+
+list.head === item // => true
+```
+
+The first item in a list, and `null` otherwise.
+
+#### `List#tail`
+
+```js
+var list = new List()
+var item1 = new Item()
+var item2 = new Item()
+
+list.tail === null // => true
+
+list.append(item1)
+list.tail === null // => true, see note.
+
+list.append(item2)
+list.tail === item2 // => true
+```
+
+The last item in a list, and `null` otherwise.
+Note that a list with only one item has **no tail**, only a head.
+
+#### `List#size`
+
+```js
+var list = new List()
+var item1 = new Item()
+var item2 = new Item()
+
+list.size === 0 // => true
+
+list.append(item1)
+list.size === 1 // => true
+
+list.append(item2)
+list.size === 2 // => true
+```
+
+The number of items in the list.
+
+### `Item()`
+
+```js
+var item = new Item()
+```
+
+Creates a new linked list Item.
+
+#### `Item#append(item)`
+
+```js
+var item1 = new Item()
+var item2 = new Item()
+
+new List().append(item1)
+
+item1.next === null // => true
+
+item1.append(item2)
+item1.next === item2 // => true
+```
+
+Adds the given item **after** the operated on item in a list.
+Throws an error when the given item has no `detach`, `append`, or `prepend`
+methods.
+Returns false when the operated on item is not attached to a list, otherwise the
+given item.
+
+#### `Item#prepend(item)`
+
+```js
+var item1 = new Item()
+var item2 = new Item()
+
+new List().append(item1)
+
+item1.prev === null // => true
+
+item1.prepend(item2)
+item1.prev === item2 // => true
+```
+
+Adds the given item **before** the operated on item in a list.
+Throws an error when the given item has no `detach`, `append`, or `prepend`
+methods.
+Returns false when the operated on item is not attached to a list, otherwise
+the given item.
+
+#### `Item#detach()`
+
+```js
+var item = new Item()
+var list = new List(item)
+
+item.list === list // => true
+
+item.detach()
+item.list === null // => true
+```
+
+Removes the operated on item from its parent list.
+Removes references to it on its parent `list`, and `prev` and `next` items;
+relinking them when possible.
+Returns the operated on item.
+Even when it was already detached.
+
+#### `Item#next`
+
+```js
+var item1 = new Item()
+var item2 = new Item()
+
+new List(item1)
+
+item1.next === null // => true
+item2.next === null // => true
+
+item1.append(item2)
+
+item1.next === item2 // => true
+
+item1.detach()
+
+item1.next === null // => true
+```
+
+The items succeeding item, and `null` otherwise.
+
+#### `Item#prev`
+
+```js
+var item1 = new Item()
+var item2 = new Item()
+
+new List(item)
+
+item1.prev === null // => true
+item2.prev === null // => true
+
+item1.append(item2)
+
+item1.prev === item1 // => true
+
+item2.detach()
+
+item2.prev === null // => true
+```
+
+The items preceding item, and `null` otherwise.
+
+#### `Item#list`
+
+```js
+var item = new Item()
+var list = new List()
+
+item.list === null // => true
+
+list.append(item)
+
+item.list === list // => true
+
+item.detach()
+
+item.list === null // => true
+```
+
+The items parent list, and `null` otherwise.
+
+## License
+
+[MIT][license] © [Titus Wormer][author]
+
+<!-- Definitions -->
+
+[build-badge]: https://github.com/wooorm/linked-list/workflows/main/badge.svg
+
+[build]: https://github.com/wooorm/linked-list/actions
+
+[coverage-badge]: https://img.shields.io/codecov/c/github/wooorm/linked-list.svg
+
+[coverage]: https://codecov.io/github/wooorm/linked-list
+
+[downloads-badge]: https://img.shields.io/npm/dm/linked-list.svg
+
+[downloads]: https://www.npmjs.com/package/linked-list
+
+[size-badge]: https://img.shields.io/bundlephobia/minzip/linked-list.svg
+
+[size]: https://bundlephobia.com/result?p=linked-list
+
+[npm]: https://docs.npmjs.com/cli/install
+
+[license]: license
+
+[author]: https://wooorm.com
+
+[wiki]: https://wikipedia.org/wiki/Linked_list

From 9e6f618ccf4dc788ce7b9d64b454b0d2c1c43f9d Mon Sep 17 00:00:00 2001
From: Gabriela Pinheiro <gpinheiro@ibm.com>
Date: Thu, 30 Jun 2022 17:19:49 -0300
Subject: [PATCH 19/24] Trail build bugfix

---
 src/trail.js | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/trail.js b/src/trail.js
index 01ec7cb..7a8e8c5 100644
--- a/src/trail.js
+++ b/src/trail.js
@@ -45,7 +45,6 @@ function Trail (id, actions, parent)
 }
 
 Trail.prototype = Object.create (HKEntity.prototype);
-Trail.prototype.constructor = Trail;
 // Trail.prototype = Object.assign(Trail.prototype, List.prototype); // Multiple inheritance with assign
 
 

From 7d229eb067230e61b2cc913ca0b6d42e0e158e36 Mon Sep 17 00:00:00 2001
From: Gabriela Pinheiro <gpinheiro@ibm.com>
Date: Fri, 1 Jul 2022 14:26:04 -0300
Subject: [PATCH 20/24] fixed indentation

---
 src/datasource/hkdatasource.js | 89 +++++++++++++++++-----------------
 src/trail.js                   | 46 +++++++++---------
 2 files changed, 68 insertions(+), 67 deletions(-)

diff --git a/src/datasource/hkdatasource.js b/src/datasource/hkdatasource.js
index 2aa4b2f..54bd3c1 100644
--- a/src/datasource/hkdatasource.js
+++ b/src/datasource/hkdatasource.js
@@ -585,51 +585,52 @@ class HKDatasource
   }
 
   /**
- * @callback GetTrailCallback
- * @param {string} err An error object that indicate if the operation was succesful or not
- * @param {object} trail 
- */
-/**
- * Fetch trail
- *
- * @param {string} trailId The trail id to retrieve their nested entities.
- * @param {GetTrailCallback} callback Callback with the entities
- */
+   * @callback GetTrailCallback
+   * @param {string} err An error object that indicate if the operation was succesful or not
+   * @param {object} trail
+   */
 
-fetchTrail(trailId, callback = () => {})
- {
-	 let url = this.url + "repository/" + this.graphName + "/trail/" + encodeURIComponent(trailId);
- 
-	 request.get(url, this.options, (err, res) =>
-	 {
-		 // console.log(res.body);
-		 if (!err)
-		 {
-			 if (requestCompletedWithSuccess(res.statusCode))
-			 {
-				 try
-				 {
-					 let entities = convertEntities(res.body);
-					 callback(null, entities[trailId]);
-				 }
-				 catch (exp)
-				 {
-					 callback(exp);
-				 }
-			 }
-
-			 else
-			 {
-				 callback(`Server responded with ${res.statusCode}. ${res.body}`);
-			 }
-		 }
-     
-		 else
-		 {
-			 callback(err);
-		 }
-	 });
- }
+  /**
+   * Fetch trail
+   *
+   * @param {string} trailId The trail id to retrieve their nested entities.
+   * @param {GetTrailCallback} callback Callback with the entities
+   */
+
+  fetchTrail(trailId, callback = () => {})
+  {
+    let url = this.url + "repository/" + this.graphName + "/trail/" + encodeURIComponent(trailId);
+  
+    request.get(url, this.options, (err, res) =>
+    {
+      // console.log(res.body);
+      if (!err)
+      {
+        if (requestCompletedWithSuccess(res.statusCode))
+        {
+          try
+          {
+            let entities = convertEntities(res.body);
+            callback(null, entities[trailId]);
+          }
+          catch (exp)
+          {
+            callback(exp);
+          }
+        }
+
+        else
+        {
+          callback(`Server responded with ${res.statusCode}. ${res.body}`);
+        }
+      }
+      
+      else
+      {
+        callback(err);
+      }
+    });
+  }
 
   /**
    * Filter entities using CSS pattern `(TODO: document it better)`
diff --git a/src/trail.js b/src/trail.js
index 7a8e8c5..126f96a 100644
--- a/src/trail.js
+++ b/src/trail.js
@@ -13,35 +13,35 @@ const HKEntity  = require('./hkentity');
 
 
 function Trail (id, actions, parent)
-  {
+{
 
-    if(arguments[0] && typeof arguments[0] === 'object' && isValid(arguments[0]))
-    {
-      let trail = arguments[0];
+  if(arguments[0] && typeof arguments[0] === 'object' && isValid(arguments[0]))
+  {
+    let trail = arguments[0];
 
-      this.id = trail.id || null;
-      this.parent = trail.parent || null;
-      this.properties = trail.properties || {};
-      this.metaproperties = trail.metaproperties || {};
-      this.interfaces = trail.interfaces || {};
-      this.actions = trail.actions || new List();
+    this.id = trail.id || null;
+    this.parent = trail.parent || null;
+    this.properties = trail.properties || {};
+    this.metaproperties = trail.metaproperties || {};
+    this.interfaces = trail.interfaces || {};
+    this.actions = trail.actions || new List();
 
-      if (this.actions && Object.keys(this.actions).length > 0) {
-        this.loadActions(); 
-      }
+    if (this.actions && Object.keys(this.actions).length > 0) {
+      this.loadActions();
     }
-    else
-    {
-      this.id = id || null;
-      this.parent = parent || null;
-      this.interfaces = {};
-      this.properties = {};
-      this.metaproperties = {};
-      this.actions = actions || new List();
+  }
+  else
+  {
+    this.id = id || null;
+    this.parent = parent || null;
+    this.interfaces = {};
+    this.properties = {};
+    this.metaproperties = {};
+    this.actions = actions || new List();
 
-    }
+  }
 
-    this.type = Types.TRAIL;
+  this.type = Types.TRAIL;
 }
 
 Trail.prototype = Object.create (HKEntity.prototype);

From f0ab249049d1e812fa9c3942561b676ac59906b4 Mon Sep 17 00:00:00 2001
From: Gabriela Pinheiro <gpinheiro@ibm.com>
Date: Fri, 1 Jul 2022 14:28:14 -0300
Subject: [PATCH 21/24] mend

---
 dist/connector.d.ts                           |   4 +-
 dist/connectorclass.d.ts                      |  14 +-
 dist/constants.d.ts                           |   4 +-
 dist/context.d.ts                             |   3 +-
 dist/datasource/hkdatasource.d.ts             |  12 +
 dist/datasource/hkdatasource.js               |  34 ++
 dist/datasource/observer/clients/index.d.ts   |   8 +-
 .../clients/rabbitmqobserverclient.d.ts       |   2 +
 .../observer/clients/restobserverclient.d.ts  |   1 +
 dist/fi/fioperator.d.ts                       |   4 +-
 dist/hkgraph.d.ts                             |  17 +-
 dist/hkgraph.js                               |  27 +-
 dist/index.js                                 |   1 +
 dist/link.d.ts                                |   4 +-
 dist/node.d.ts                                |  10 +-
 dist/reference.d.ts                           |   9 +-
 dist/roletypes.d.ts                           |  10 +-
 dist/trail.d.ts                               |  78 ++-
 dist/trail.js                                 | 483 ++++++++++++++----
 dist/types.d.ts                               |  25 +-
 dist/types.js                                 |   1 +
 dist/virtualcontext.js                        |   2 +-
 dist/virtuallink.js                           |   2 +-
 dist/virtualnode.js                           |   2 +-
 24 files changed, 600 insertions(+), 157 deletions(-)

diff --git a/dist/connector.d.ts b/dist/connector.d.ts
index e94e3af..537f136 100644
--- a/dist/connector.d.ts
+++ b/dist/connector.d.ts
@@ -48,6 +48,8 @@ declare class Connector extends HKEntity {
     public roles: {
         [x: string]: string;
     };
+    properties: any;
+    metaProperties: any;
     /**
      * Adds a new role to this connector.
      *
@@ -96,6 +98,6 @@ declare class Connector extends HKEntity {
     };
 }
 declare namespace Connector {
-    const type: string;
+    const type: "connector";
 }
 import HKEntity = require("./hkentity");
diff --git a/dist/connectorclass.d.ts b/dist/connectorclass.d.ts
index e271c8f..14286dd 100644
--- a/dist/connectorclass.d.ts
+++ b/dist/connectorclass.d.ts
@@ -2,10 +2,10 @@
 * Copyright (c) 2016-present, IBM Research
 * Licensed under The MIT License [see LICENSE for details]
 */
-export var HIERARCHY: string;
-export var FACTS: string;
-export var REASONING: string;
-export var CONSTRAINT: string;
-export var CAUSAL: string;
-export var POSSIBILITY: string;
-export var POSSIBILITYRESOLVER: string;
+export const HIERARCHY: "h";
+export const FACTS: "f";
+export const REASONING: "r";
+export const CONSTRAINT: "c";
+export const CAUSAL: "C";
+export const POSSIBILITY: "p";
+export const POSSIBILITYRESOLVER: "P";
diff --git a/dist/constants.d.ts b/dist/constants.d.ts
index 1b39eba..3e75fe1 100644
--- a/dist/constants.d.ts
+++ b/dist/constants.d.ts
@@ -2,5 +2,5 @@
 * Copyright (c) 2016-present, IBM Research
 * Licensed under The MIT License [see LICENSE for details]
 */
-export var LAMBDA: string;
-export var MIMETYPE: string;
+export const LAMBDA: "λ";
+export const MIMETYPE: "hk:mimeType";
diff --git a/dist/context.d.ts b/dist/context.d.ts
index a66a098..9530077 100644
--- a/dist/context.d.ts
+++ b/dist/context.d.ts
@@ -10,8 +10,9 @@ declare class Context extends Node {
      * @param {string | null} [parent] Parent id.
      */
     constructor(id?: string | null | undefined, parent?: string | null | undefined);
+    type: "context";
 }
 declare namespace Context {
-    const type: string;
+    const type: "context";
 }
 import Node = require("./node");
diff --git a/dist/datasource/hkdatasource.d.ts b/dist/datasource/hkdatasource.d.ts
index 569a981..6068588 100644
--- a/dist/datasource/hkdatasource.d.ts
+++ b/dist/datasource/hkdatasource.d.ts
@@ -147,6 +147,18 @@ declare class HKDatasource {
     }, payload: object, callback: (err: string, entities: {
         [x: string]: HKEntity;
     }) => any): void;
+    /**
+   * @callback GetTrailCallback
+   * @param {string} err An error object that indicate if the operation was succesful or not
+   * @param {object} trail
+   */
+    /**
+     * Fetch trail
+     *
+     * @param {string} trailId The trail id to retrieve their nested entities.
+     * @param {GetTrailCallback} callback Callback with the entities
+     */
+    fetchTrail(trailId: string, callback?: (err: string, trail: object) => any): void;
     /**
      * Filter entities using CSS pattern `(TODO: document it better)`
      *
diff --git a/dist/datasource/hkdatasource.js b/dist/datasource/hkdatasource.js
index cf3e83c..28ed760 100644
--- a/dist/datasource/hkdatasource.js
+++ b/dist/datasource/hkdatasource.js
@@ -417,6 +417,40 @@ class HKDatasource {
             }
         });
     }
+    /**
+   * @callback GetTrailCallback
+   * @param {string} err An error object that indicate if the operation was succesful or not
+   * @param {object} trail
+   */
+    /**
+     * Fetch trail
+     *
+     * @param {string} trailId The trail id to retrieve their nested entities.
+     * @param {GetTrailCallback} callback Callback with the entities
+     */
+    fetchTrail(trailId, callback = () => { }) {
+        let url = this.url + "repository/" + this.graphName + "/trail/" + encodeURIComponent(trailId);
+        request.get(url, this.options, (err, res) => {
+            // console.log(res.body);
+            if (!err) {
+                if (requestCompletedWithSuccess(res.statusCode)) {
+                    try {
+                        let entities = convertEntities(res.body);
+                        callback(null, entities[trailId]);
+                    }
+                    catch (exp) {
+                        callback(exp);
+                    }
+                }
+                else {
+                    callback(`Server responded with ${res.statusCode}. ${res.body}`);
+                }
+            }
+            else {
+                callback(err);
+            }
+        });
+    }
     /**
      * Filter entities using CSS pattern `(TODO: document it better)`
      *
diff --git a/dist/datasource/observer/clients/index.d.ts b/dist/datasource/observer/clients/index.d.ts
index a830568..c47b151 100644
--- a/dist/datasource/observer/clients/index.d.ts
+++ b/dist/datasource/observer/clients/index.d.ts
@@ -2,7 +2,7 @@
 * Copyright (c) 2016-present, IBM Research
 * Licensed under The MIT License [see LICENSE for details]
 */
-export var DefaultObserverClient: typeof import("./observerclient");
-export var ConfigurableObserverClient: typeof import("./configurableobserverclient");
-export var RestObserverClient: typeof import("./restobserverclient");
-export var RabbitMQObserverClient: typeof import("./rabbitmqobserverclient");
+export const DefaultObserverClient: typeof import("./observerclient");
+export const ConfigurableObserverClient: typeof import("./configurableobserverclient");
+export const RestObserverClient: typeof import("./restobserverclient");
+export const RabbitMQObserverClient: typeof import("./rabbitmqobserverclient");
diff --git a/dist/datasource/observer/clients/rabbitmqobserverclient.d.ts b/dist/datasource/observer/clients/rabbitmqobserverclient.d.ts
index 4967183..cabd9a1 100644
--- a/dist/datasource/observer/clients/rabbitmqobserverclient.d.ts
+++ b/dist/datasource/observer/clients/rabbitmqobserverclient.d.ts
@@ -35,7 +35,9 @@ declare class RabbitMQObserverClient extends ConfigurableObserverClient {
     _channelWrapper: any;
     _setupFunction: ((channel: any) => Promise<void>) | null;
     _queueName: any;
+    init(): Promise<void>;
     _init(exchangeName: any): Promise<void>;
     _isInitialized: boolean | undefined;
+    deinit(): Promise<void>;
 }
 import ConfigurableObserverClient = require("./configurableobserverclient");
diff --git a/dist/datasource/observer/clients/restobserverclient.d.ts b/dist/datasource/observer/clients/restobserverclient.d.ts
index 320c80d..5f9e354 100644
--- a/dist/datasource/observer/clients/restobserverclient.d.ts
+++ b/dist/datasource/observer/clients/restobserverclient.d.ts
@@ -25,5 +25,6 @@ declare class RestObserverClient extends ConfigurableObserverClient {
     _address: string;
     _listeningPath: string | null;
     _server: any;
+    deinit(): Promise<void>;
 }
 import ConfigurableObserverClient = require("./configurableobserverclient");
diff --git a/dist/fi/fioperator.d.ts b/dist/fi/fioperator.d.ts
index 6b04ff8..bb996e0 100644
--- a/dist/fi/fioperator.d.ts
+++ b/dist/fi/fioperator.d.ts
@@ -4,6 +4,6 @@
 */
 export = FIOperator;
 declare const FIOperator: Readonly<{
-    NONE: string;
-    DESCRIPTION: string;
+    NONE: "";
+    DESCRIPTION: "*";
 }>;
diff --git a/dist/hkgraph.d.ts b/dist/hkgraph.d.ts
index d9de5ab..e6ebf8c 100644
--- a/dist/hkgraph.d.ts
+++ b/dist/hkgraph.d.ts
@@ -13,6 +13,7 @@ declare class HKGraph {
     connectors: {};
     refs: {};
     trails: {};
+    actions: {};
     bindsMap: {};
     linkMap: {};
     virtualLinkMap: {};
@@ -75,14 +76,14 @@ declare class HKGraph {
     deserialize(str: any): HKGraph;
 }
 declare namespace HKGraph {
-    const NODE_TYPE: string;
-    const VIRTUAL_NODE_TYPE: string;
-    const CONTEXT_TYPE: string;
-    const VIRTUAL_CONTEXT_TYPE: string;
-    const LINK_TYPE: string;
-    const VIRTUAL_LINK_TYPE: string;
-    const CONNECTOR_TYPE: string;
-    const INTERFACE: string;
+    const NODE_TYPE: "node";
+    const VIRTUAL_NODE_TYPE: "virtualnode";
+    const CONTEXT_TYPE: "context";
+    const VIRTUAL_CONTEXT_TYPE: "virtualcontext";
+    const LINK_TYPE: "link";
+    const VIRTUAL_LINK_TYPE: "virtuallink";
+    const CONNECTOR_TYPE: "connector";
+    const INTERFACE: "interface";
 }
 declare function generateId(model: any, length: any): any;
 import HKEntity = require("./hkentity");
diff --git a/dist/hkgraph.js b/dist/hkgraph.js
index 52c1772..82f5a9a 100644
--- a/dist/hkgraph.js
+++ b/dist/hkgraph.js
@@ -11,6 +11,7 @@ const Reference = require("./reference");
 const Trail = require("./trail");
 const HKTypes = require("./types");
 const shortId = require('shortid');
+const { Action } = require("./trail");
 const VirtualContext = require("./virtualcontext");
 const HKEntity = require("./hkentity");
 const VirtualNode = require("./virtualnode");
@@ -26,6 +27,7 @@ class HKGraph {
         this.connectors = {};
         this.refs = {};
         this.trails = {};
+        this.actions = {};
         // Auxiliar maps
         this.bindsMap = {};
         this.linkMap = {};
@@ -47,7 +49,8 @@ class HKGraph {
             this.links.hasOwnProperty(id) ||
             this.connectors.hasOwnProperty(id) ||
             this.refs.hasOwnProperty(id) ||
-            this.trails.hasOwnProperty(id);
+            this.trails.hasOwnProperty(id) ||
+            this.actions.hasOwnProperty(id);
     }
     /**
      * Update an entity
@@ -66,7 +69,7 @@ class HKGraph {
             oldEntity.roles = entity.roles;
             oldEntity.className = entity.className;
         }
-        if (entity.type === HKTypes.NODE || entity.type === HKTypes.REFERENCE || entity.type === HKTypes.CONTEXT || entity.type === HKTypes.VIRTUAL_NODE || entity.type === HKTypes.VIRTUAL_CONTEXT) {
+        if (entity.type === HKTypes.NODE || entity.type === HKTypes.TRAIL || entity.type === HKTypes.REFERENCE || entity.type === HKTypes.CONTEXT || entity.type === HKTypes.VIRTUAL_NODE || entity.type === HKTypes.VIRTUAL_CONTEXT || entity.type === HKTypes.ACTION) {
             oldEntity.interfaces = entity.interfaces;
         }
         // Update parent
@@ -173,6 +176,19 @@ class HKGraph {
                         if (Trail.isValid(entity)) {
                             newEntity = new Trail(entity);
                             this.trails[entity.id] = newEntity;
+                            this.contextMap[entity.id] = {};
+                            if (this.orphans.hasOwnProperty(entity.id)) {
+                                this.contextMap[entity.id] = this.orphans[entity.id];
+                                delete this.orphans[entity.id];
+                            }
+                        }
+                        break;
+                    }
+                case HKTypes.ACTION:
+                    {
+                        if (entity instanceof Trail.Action) {
+                            newEntity = entity;
+                            this.actions[entity.id] = newEntity;
                         }
                         break;
                     }
@@ -356,8 +372,13 @@ class HKGraph {
                     {
                         /* delete children trails? */
                         delete this.trails[id];
+                        delete this.contextMap[entity.id];
                         break;
                     }
+                case Action.type:
+                    {
+                        delete this.actions[id];
+                    }
             }
             if (this.orphans.hasOwnProperty(entity.parent)) {
                 delete this.orphans[entity.parent][id];
@@ -480,7 +501,7 @@ class HKGraph {
             c.id = null;
             return c;
         }
-        return this.nodes[id] || this.virtualNodes[id] || this.contexts[id] || this.virtualContexts[id] || this.virtualLinks[id] || this.links[id] || this.connectors[id] || this.refs[id] || this.trails[id] || null;
+        return this.nodes[id] || this.virtualNodes[id] || this.contexts[id] || this.virtualContexts[id] || this.virtualLinks[id] || this.links[id] || this.connectors[id] || this.refs[id] || this.trails[id] || this.actions[id] || null;
     }
     /**
      * Returns HK entities in this graph indexed by id.
diff --git a/dist/index.js b/dist/index.js
index 188c9cd..3bb9002 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -32,6 +32,7 @@ exports.CONNECTOR_TYPE = require("./types").CONNECTOR;
 exports.BIND_TYPE = require("./types").BIND;
 exports.INTERFACE = require("./types").INTERFACE;
 exports.TRAIL_TYPE = require("./types").TRAIL;
+exports.ACTION_TYPE = require("./types").ACTION;
 exports.VIRTUAL_NODE_TYPE = require("./types").VIRTUAL_NODE;
 exports.VIRTUAL_CONTEXT_TYPE = require("./types").VIRTUAL_CONTEXT;
 exports.VIRTUAL_LINK_TYPE = require("./types").VIRTUAL_LINK;
diff --git a/dist/link.d.ts b/dist/link.d.ts
index df42d86..a68f7c6 100644
--- a/dist/link.d.ts
+++ b/dist/link.d.ts
@@ -54,6 +54,8 @@ declare class Link extends HKEntity {
             [x: string]: Object;
         };
     };
+    properties: any;
+    metaProperties: any;
     /**
      * Adds a new bind to this role;
      *
@@ -91,6 +93,6 @@ declare class Link extends HKEntity {
     };
 }
 declare namespace Link {
-    const type: string;
+    const type: "link";
 }
 import HKEntity = require("./hkentity");
diff --git a/dist/node.d.ts b/dist/node.d.ts
index 4547689..6711716 100644
--- a/dist/node.d.ts
+++ b/dist/node.d.ts
@@ -60,6 +60,14 @@ declare class Node extends HKEntity {
             };
         };
     };
+    /**
+     * @public
+     * @type {Object.<string, string | number | Object>
+     */
+    public properties: {
+        [x: string]: string | number | Object;
+    };
+    metaProperties: any;
     /**
      *
      * @param {string} key Id of the interface
@@ -88,7 +96,7 @@ declare class Node extends HKEntity {
     };
 }
 declare namespace Node {
-    const type: string;
+    const type: "node";
 }
 import HKEntity = require("./hkentity");
 import FI = require("./fi/fi");
diff --git a/dist/reference.d.ts b/dist/reference.d.ts
index 9656433..152372c 100644
--- a/dist/reference.d.ts
+++ b/dist/reference.d.ts
@@ -20,8 +20,15 @@ declare class Reference extends Node {
      *
      */
     public ref: string | null;
+    type: "ref";
+    serialize: () => {
+        id: any;
+        type: "ref";
+        ref: any;
+        parent: any;
+    };
 }
 declare namespace Reference {
-    const type: string;
+    const type: "ref";
 }
 import Node = require("./node");
diff --git a/dist/roletypes.d.ts b/dist/roletypes.d.ts
index b1e3c10..cd83553 100644
--- a/dist/roletypes.d.ts
+++ b/dist/roletypes.d.ts
@@ -2,8 +2,8 @@
 * Copyright (c) 2016-present, IBM Research
 * Licensed under The MIT License [see LICENSE for details]
 */
-export var NONE: string;
-export var SUBJECT: string;
-export var OBJECT: string;
-export var PARENT: string;
-export var CHILD: string;
+export const NONE: "n";
+export const SUBJECT: "s";
+export const OBJECT: "o";
+export const PARENT: "p";
+export const CHILD: "c";
diff --git a/dist/trail.d.ts b/dist/trail.d.ts
index 6bb2f2a..948a90f 100644
--- a/dist/trail.d.ts
+++ b/dist/trail.d.ts
@@ -3,29 +3,83 @@
 * Licensed under The MIT License [see LICENSE for details]
 */
 export = Trail;
-declare class Trail extends HKEntity {
-    static isValid(entity: any): boolean;
-    constructor(id: any, parent: any, ...args: any[]);
+declare function Trail(id: any, actions: any, parent: any, ...args: any[]): void;
+declare class Trail {
+    constructor(id: any, actions: any, parent: any, ...args: any[]);
     id: any;
     parent: any;
+    properties: any;
     metaproperties: any;
     interfaces: any;
-    children: any;
-    steps: any[] | undefined;
-    addStep(key: any, properties: any): void;
-    addInterface(key: any, type: any, properties: any): void;
-    createLinksFromSteps(): Connector[];
+    actions: any;
+    type: "trail";
+    updateAction(oldAction: any, newAction: any): void;
+    addAction(action: any): any;
+    removeAction(action: any): void;
+    action: any;
+    append(action: any): any;
+    prepend(action: any): any;
+    in(from?: null): any;
+    out(to?: null): any;
+    size(): number | undefined;
+    join(delimiter: any): any;
+    update(action: any, newAction: any): void;
+    remove(action: any): void;
+    getPrev(position: any, num?: number): any;
+    getNext(position: any, num?: number): any;
+    getPositionOf(action: any): number;
+    getActionAt(position: any): any;
+    search(eventId: null | undefined, filters: any): any;
+    loadActions(actions?: null): any;
+    toJSON(): {
+        id: any;
+        parent: any;
+        properties: any;
+        metaproperties: any;
+        interfaces: any;
+        actions: any[];
+        type: "trail";
+    };
     serialize(): {
         id: any;
         parent: any;
         properties: any;
         metaproperties: any;
         interfaces: any;
-        type: string;
+        actions: any;
+        type: "trail";
     };
 }
 declare namespace Trail {
-    const type: string;
+    export const type: "trail";
+    export { isValid };
+    export { sort };
+    export { Action };
+    export { TrailNode };
+}
+declare function isValid(entity: any): boolean;
+declare function sort(actions?: null): any;
+declare class Action {
+    constructor({ from, to, event, agent }?: {
+        from?: null | undefined;
+        to?: null | undefined;
+        event?: {} | undefined;
+        agent?: null | undefined;
+    });
+    from: any;
+    to: any;
+    agent: any;
+    event: {};
+    type: "action";
+    id: any;
+    getTime(): number;
+    toString(): any;
+    toJSON(): any;
+}
+declare class TrailNode {
+    constructor(nodeId: any, nodeType: any, targetAnchor: any);
+    nodeId: any;
+    nodeType: any;
+    targetAnchor: any;
+    toString(): string;
 }
-import HKEntity = require("./hkentity");
-import Connector = require("./connector");
diff --git a/dist/trail.js b/dist/trail.js
index 2c1186c..2e2235d 100644
--- a/dist/trail.js
+++ b/dist/trail.js
@@ -1,113 +1,408 @@
-/**
+/*
  * Copyright (c) 2016-present, IBM Research
  * Licensed under The MIT License [see LICENSE for details]
  */
 'use strict';
-const shortid = require('shortid');
+const { List, Item } = require('linked-list');
+// const shortid   = require('shortid');
 const Types = require('./types');
 const HKEntity = require('./hkentity');
-const Connector = require('./connector');
-const Link = require('./link');
-const RoleTypes = require('./roletypes');
-const CONNECTOR_NAME = 'occurs';
-const vConnector = new Connector(CONNECTOR_NAME, 'f');
-vConnector.addRole('sub', RoleTypes.SUBJECT);
-vConnector.addRole('obj', RoleTypes.OBJECT);
-class Trail extends HKEntity {
-    constructor(id, parent) {
-        super();
-        if (arguments[0] && typeof arguments[0] === 'object' && isValid(arguments[0])) {
-            let trail = arguments[0];
-            this.id = trail.id || null;
-            this.parent = trail.parent || null;
-            this.properties = trail.properties || {};
-            this.metaproperties = trail.metaproperties || {};
-            this.interfaces = trail.interfaces || {};
-            this.children = trail.children || [];
-            _loadSteps.call(this);
+function Trail(id, actions, parent) {
+    if (arguments[0] && typeof arguments[0] === 'object' && isValid(arguments[0])) {
+        let trail = arguments[0];
+        this.id = trail.id || null;
+        this.parent = trail.parent || null;
+        this.properties = trail.properties || {};
+        this.metaproperties = trail.metaproperties || {};
+        this.interfaces = trail.interfaces || {};
+        this.actions = trail.actions || new List();
+        if (this.actions && Object.keys(this.actions).length > 0) {
+            this.loadActions();
+        }
+    }
+    else {
+        this.id = id || null;
+        this.parent = parent || null;
+        this.interfaces = {};
+        this.properties = {};
+        this.metaproperties = {};
+        this.actions = actions || new List();
+    }
+    this.type = Types.TRAIL;
+}
+Trail.prototype = Object.create(HKEntity.prototype);
+//Trail.prototype.constructor = Trail;
+// Trail.prototype = Object.assign(Trail.prototype, List.prototype); // Multiple inheritance with assign
+// Update a given action in trail
+Trail.prototype.updateAction = function (oldAction, newAction) {
+    oldAction.prepend(newAction);
+    oldAction.detach();
+};
+// Add an action to a trail respecting timestamp ordering
+Trail.prototype.addAction = function (action) {
+    var current = this.actions.head;
+    while (current) {
+        if (new Date(current.event['timestamp']) - new Date(action.event['timestamp'])) {
+            return current.prepend(action);
+        }
+        current = current.next;
+    }
+    return this.actions.append(action);
+};
+// Remove an action from trail using its reference
+Trail.prototype.removeAction = function (action) {
+    var action;
+    if (typeof (action) === 'string') {
+        this.action = this.search(action);
+        //action not found
+        if (!this.action) {
+            return;
+        }
+    }
+    else {
+        this.action = action;
+    }
+    this.action.detach();
+};
+// `append` and `prepend` operations are 
+// handled by our linked list structure
+Trail.prototype.append = function (action) {
+    return this.actions.append(action);
+};
+Trail.prototype.prepend = function (action) {
+    return this.actions.prepend(action);
+};
+// aliases `in` and `out` represent the input and
+// output TrailNodes for a trail, which conceptually is
+// done through the use of Port elements in Hyperknowledge
+Trail.prototype.in = function (from = null) {
+    if (from) {
+        this.actions.head.from = from;
+    }
+    return this.actions.head.from;
+};
+Trail.prototype.out = function (to = null) {
+    if (this.actions.tail) {
+        if (to) {
+            this.actions.tail.to = to;
+        }
+        return this.actions.tail.to;
+    }
+    if (to) {
+        this.actions.head.to = to;
+    }
+    return this.actions.head.to;
+};
+Trail.prototype.size = function () {
+    if (this.actions.constructor === List) {
+        return this.actions.size;
+    }
+    else if (Array.isArray(this.actions)) {
+        return this.actions.length;
+    }
+};
+Trail.prototype.join = function (delimiter) {
+    return this.actions.toArray().join(delimiter);
+};
+// Update a given action in the trail
+Trail.prototype.update = function (action, newAction) {
+    action.prepend(newAction);
+    action.detach();
+};
+// Remove an action from the trail using its reference
+Trail.prototype.remove = function (action) {
+    var action;
+    if (typeof (action) === 'string') {
+        this.action = this.search(action);
+        //action not found
+        if (!this.action) {
+            return;
+        }
+    }
+    else {
+        this.action = action;
+    }
+    this.action.detach();
+};
+// Get `num` actions (or the available ones) before `position`
+Trail.prototype.getPrev = function (position, num = 1) {
+    //check if it is a valid position
+    if (position >= this.actions.size || position <= 1 || this.actions.size <= 1) {
+        return;
+    }
+    // get actions
+    var action = this.actions.toArray()[position];
+    var resultSet = [];
+    while (action && action.prev) {
+        if (resultSet.length >= num) {
+            if (resultSet.length == 1 && num == 1) {
+                return resultSet[0];
+            }
+            return resultSet;
         }
         else {
-            this.id = id || null;
-            this.parent = parent || null;
-            this.interfaces = {};
-            this.properties = {};
-            this.metaproperties = {};
-            this.children = [];
-            this.steps = [];
-        }
-        this.type = Types.TRAIL;
-    }
-    addStep(key, properties) {
-        let ts = properties.begin || new Date().toISOString();
-        properties.begin = ts;
-        if (this.steps.length > 0) {
-            let lastStep = this.steps[this.steps.length - 1].key;
-            if (!this.interfaces[lastStep].properties.end) {
-                this.interfaces[lastStep].properties.end = ts;
+            resultSet.push(action.prev);
+        }
+        action = action.prev;
+    }
+    return resultSet;
+};
+// Get `num` actions (or a n<num available ones) after `position`
+// if a number is not given, 1 is assumed
+Trail.prototype.getNext = function (position, num = 1) {
+    // check if it is a valid position
+    if (position >= this.actions.size || position <= 1 || this.actions.size <= 1) {
+        return;
+    }
+    // get actions
+    var action = this.actions.toArray()[position];
+    var resultSet = [];
+    while (action && action.next) {
+        if (resultSet.length >= num) {
+            if (resultSet.length == 1 && num == 1) {
+                return resultSet[0];
             }
         }
-        this.steps.push({ key: key, begin: ts });
-        this.addInterface(key, 'temporal', properties);
-    }
-    addInterface(key, type, properties) {
-        this.interfaces[key] = { type: type, properties: properties };
-    }
-    createLinksFromSteps() {
-        let vEntities = [vConnector];
-        for (let key in this.interfaces) {
-            let interProp = this.interfaces[key].properties;
-            if (!interProp)
-                continue;
-            if (interProp.obj) {
-                let l = new Link(shortid(), vConnector.id, this.parent);
-                l.addBind('sub', interProp.obj, interProp.objInterface);
-                l.addBind('obj', this.id);
-                vEntities.push(l);
+        else {
+            resultSet.push(action.next);
+        }
+        action = action.next;
+    }
+    return resultSet;
+};
+// Get the position of an action in the list,
+// it might be useful for pagination. Returns 
+// -1 in case action is not found in the list
+Trail.prototype.getPositionOf = function (action) {
+    //search action by eventId
+    var array = this.actions.toArray();
+    for (var i = 0; i < this.actions.size; i++) {
+        if (array[i].event["id"] == action.event["id"]) {
+            return i;
+        }
+    }
+    return -1;
+};
+// Get an action at specified position
+// a position = 0 is equivalent to trail.head
+Trail.prototype.getActionAt = function (position) {
+    //check if it is a valid position
+    if (position < 0 || position >= this.actions.size) {
+        return;
+    }
+    //return action by position in array
+    return this.actions.toArray()[position];
+};
+// Search for action(s) either by an event identifier or by filters
+Trail.prototype.search = function (eventId = null, filters) {
+    if (!filters && eventId instanceof String) {
+        filters = { 'from': null, 'fromAnchor': 'lambda', 'to': null, 'toAnchor': 'lambda' };
+    }
+    else if (!filters && eventId instanceof Object) {
+        filters = eventId;
+        eventId = null;
+    }
+    // nothing to be found
+    if (!eventId && !filters['from'] && !filters['to']) {
+        return;
+    }
+    // search actions by eventId
+    var array = this.actions.toArray();
+    if (eventId) {
+        for (var i = 0; i < this.actions.size; i++) {
+            if (array[i].event["id"] == eventId) {
+                return array[i];
             }
         }
-        return vEntities;
-    }
-    serialize() {
-        return {
-            id: this.id,
-            parent: this.parent,
-            properties: this.properties,
-            metaproperties: this.metaproperties,
-            interfaces: this.interfaces,
-            type: this.type
-        };
-    }
-    static isValid(entity) {
-        let isValid = false;
-        if (entity && typeof (entity) === 'object' && !Array.isArray(entity)) {
-            if (entity.hasOwnProperty('type') && entity.type === Types.TRAIL &&
-                entity.hasOwnProperty('id') && entity.hasOwnProperty('parent')) {
-                isValid = true;
+        return;
+    }
+    // search actions by filters
+    var resultSet = [];
+    for (var i = 0; i < this.actions.size; i++) {
+        if ((filters['from'] && filters['to']) && array[i].from == filters['from'] && array[i].to == filters['to']) {
+            resultSet.push(array[i]);
+        }
+        else if (array[i].from == filters['from'] || array[i].to == filters['to']) {
+            resultSet.push(array[i]);
+        }
+    }
+    return resultSet;
+};
+Trail.prototype.loadActions = function (actions = null) {
+    // use array of actions if passed
+    if (actions && Array.isArray(actions)) {
+        if (actions[0].event.timestamp) {
+            this.actions = new List(...sort(actions));
+        }
+        else {
+            this.actions = new List(...actions);
+        }
+        return this.actions;
+    }
+    let actionArray = [];
+    let actionIds = [];
+    for (let i in this.actions) {
+        // create Action object from json object
+        if (this.actions[i] && this.actions[i].hasOwnProperty("from") &&
+            this.actions[i].hasOwnProperty("to") &&
+            this.actions[i].hasOwnProperty("agent") &&
+            this.actions[i].hasOwnProperty("event")) {
+            let from = new TrailNode(this.actions[i].from.nodeId, this.actions[i].from.nodeType, this.actions[i].from.targetAnchor);
+            let to = new TrailNode(this.actions[i].to.nodeId, this.actions[i].to.nodeType, this.actions[i].to.targetAnchor);
+            let event = { "id": this.actions[i].event.id, "type": this.actions[i].event.type, "properties": this.actions[i].event.properties, "timestamp": new Date(this.actions[i].event.timestamp) };
+            let agent = this.actions[i].agent;
+            actionArray.push(new Action({ from, to, event, agent }));
+        }
+        else if (this.actions[i] && this.actions[i].hasOwnProperty("event") && this.actions[i].event.hasOwnProperty("timestamp")) {
+            // we got event's id and timestamp
+            actionArray.push(new Action({ event: { "id": i, "timestamp": new Date(this.actions[i].event.timestamp) } }));
+        }
+        else if (Array.isArray(this.actions)) {
+            // all we got is an Array with the event's id
+            actionIds.push(this.actions[i]);
+        }
+        else {
+            // all we got is event's id
+            actionIds.push(i);
+        }
+    }
+    // sort action items before creating list
+    if (actionArray.length > 0) {
+        this.actions = new List(...sort(actionArray));
+    }
+    else if (actionIds.length > 0) {
+        this.actions = actionIds;
+    }
+};
+function isValid(entity) {
+    let isValid = false;
+    if (entity && typeof (entity) === 'object' && !Array.isArray(entity)) {
+        if (entity.hasOwnProperty('type') && entity.type === Types.TRAIL &&
+            entity.hasOwnProperty('id') && entity.hasOwnProperty('parent')) {
+            isValid = true;
+        }
+    }
+    return isValid;
+}
+function sort(actions = null) {
+    if (actions && Array.isArray(actions) && actions[0].event.timestamp.constructor === Date) {
+        // sort and return object array based on timestamp
+        return actions.sort(function (action1, action2) {
+            return action1.event['timestamp'] - action2.event['timestamp'];
+        });
+    }
+    else if (actions && Array.isArray(actions) && (actions[0].event.timestamp.constructor === String || actions[0].event.timestamp.constructor === Number)) {
+        // sort Action array based on timestamp
+        return actions.sort(function (action1, action2) {
+            return new Date(action1.event['timestamp']) - new Date(action2.event['timestamp']);
+        });
+    }
+}
+Trail.prototype.toJSON = function () {
+    let actionArray = [];
+    if (this.actions.constructor === List) {
+        //in case we have only action ids and timestamps
+        if (this.actions.head && (!this.actions.head.from && !this.actions.head.to && !this.actions.head.agent)) {
+            let action = this.actions.head;
+            while (action) {
+                actionArray.push(action.id);
+                action = action.next;
             }
         }
-        return isValid;
+        else {
+            actionArray = this.actions.toArray();
+        }
+    }
+    else if (Array.isArray(this.actions)) {
+        actionArray = this.actions;
+    }
+    return {
+        id: this.id,
+        parent: this.parent,
+        properties: this.properties,
+        metaproperties: this.metaproperties,
+        interfaces: this.interfaces,
+        actions: actionArray,
+        type: this.type
+    };
+};
+Trail.prototype.serialize = function () {
+    let actions;
+    if (this.actions instanceof Array) {
+        actions = this.actions;
+    }
+    else {
+        actions = this.actions.toArray();
+    }
+    return {
+        id: this.id,
+        parent: this.parent,
+        properties: this.properties,
+        metaproperties: this.metaproperties,
+        interfaces: this.interfaces,
+        actions: actions,
+        type: this.type
+    };
+};
+// TrailNode is basically an envelope for a hknode and a target anchor
+class TrailNode {
+    constructor(nodeId, nodeType, targetAnchor) {
+        this.nodeId = nodeId;
+        this.nodeType = nodeType;
+        this.targetAnchor = targetAnchor;
+    }
+    toString() {
+        return this.nodeId + "#" + this.targetAnchor;
     }
 }
-function _loadSteps() {
-    let steps = [];
-    for (let key in this.interfaces) {
-        let begin = new Date(Date.parse(this.interfaces[key].properties.begin));
-        let end = new Date(Date.parse(this.interfaces[key].properties.end));
-        this.interfaces[key].properties.begin = begin;
-        this.interfaces[key].properties.end = end;
-        steps.push({ key: key, begin: begin });
-    }
-    steps.sort((a, b) => {
-        if (a.begin < b.begin) {
-            return -1;
-        }
-        if (a.begin > b.begin) {
-            return 1;
-        }
-        return 0;
-    });
-    this.steps = steps;
+// actions hold references to source and destination trail 
+// nodes (along with their respective target anchors), 
+// the related event and an agent (user, system or content).
+class Action extends Item {
+    constructor({ from = null, to = null, event = {}, agent = null } = {}) {
+        super();
+        this.from = from;
+        this.to = to;
+        this.agent = agent;
+        this.event = event;
+        this.type = Types.ACTION;
+        // create timestamp if needed
+        // if(!this.event['timestamp'])
+        // {
+        //     this.event['timestamp'] = new Date().getTime();
+        // }
+        // get event id or create a new one
+        if (!this.event['id'] || this.event['id'] == '') {
+            this.event['id'] = this.event.type + '_' + this.event.timestamp;
+            this.id = this.event['id'];
+        }
+        else {
+            this.id = this.event['id'];
+        }
+    }
+    getTime() {
+        return new Date(this.event['timestamp']).getTime();
+    }
+    toString() {
+        if (this.from && this.to && this.agent && this.event && this.event.id) {
+            return JSON.stringify({ from: this.from, to: this.to, agent: this.agent, event: this.event, id: this.event.id });
+        }
+        else {
+            return this.event.id;
+        }
+    }
+    toJSON() {
+        if (this.from && this.to && this.agent && this.event && this.event.id) {
+            return { from: this.from, to: this.to, agent: this.agent, event: this.event, id: this.event.id };
+        }
+        else {
+            return this.event.id;
+        }
+    }
 }
 Trail.type = Types.TRAIL;
-const isValid = Trail.isValid;
+Trail.isValid = isValid;
+Trail.sort = sort;
+Trail.Action = Action;
+Trail.TrailNode = TrailNode;
 module.exports = Trail;
diff --git a/dist/types.d.ts b/dist/types.d.ts
index a59c438..2948170 100644
--- a/dist/types.d.ts
+++ b/dist/types.d.ts
@@ -2,16 +2,17 @@
 * Copyright (c) 2016-present, IBM Research
 * Licensed under The MIT License [see LICENSE for details]
 */
-export var NODE: string;
-export var CONTEXT: string;
-export var LINK: string;
-export var CONNECTOR: string;
-export var REFERENCE: string;
-export var INTERFACE: string;
-export var BIND: string;
-export var TRAIL: string;
-export var VIRTUAL_NODE: string;
-export var VIRTUAL_CONTEXT: string;
-export var VIRTUAL_LINK: string;
-export var VIRTUAL_SOURCE_PROPERTY: string;
+export const NODE: "node";
+export const CONTEXT: "context";
+export const LINK: "link";
+export const CONNECTOR: "connector";
+export const REFERENCE: "ref";
+export const INTERFACE: "interface";
+export const BIND: "bind";
+export const TRAIL: "trail";
+export const ACTION: "action";
+export const VIRTUAL_NODE: "virtualnode";
+export const VIRTUAL_CONTEXT: "virtualcontext";
+export const VIRTUAL_LINK: "virtuallink";
+export const VIRTUAL_SOURCE_PROPERTY: "virtualsrc";
 export function isValidType(type: any): boolean;
diff --git a/dist/types.js b/dist/types.js
index 46f60eb..fff6183 100644
--- a/dist/types.js
+++ b/dist/types.js
@@ -11,6 +11,7 @@ exports.REFERENCE = 'ref';
 exports.INTERFACE = 'interface';
 exports.BIND = 'bind';
 exports.TRAIL = 'trail';
+exports.ACTION = 'action';
 exports.VIRTUAL_NODE = 'virtualnode';
 exports.VIRTUAL_CONTEXT = 'virtualcontext';
 exports.VIRTUAL_LINK = 'virtuallink';
diff --git a/dist/virtualcontext.js b/dist/virtualcontext.js
index a9e4ac0..5d7bf58 100644
--- a/dist/virtualcontext.js
+++ b/dist/virtualcontext.js
@@ -5,7 +5,7 @@
  */
 const tslib_1 = require("tslib");
 const types_1 = require("./types");
-const context_1 = (0, tslib_1.__importDefault)(require("./context"));
+const context_1 = tslib_1.__importDefault(require("./context"));
 class VirtualContext extends context_1.default {
     /** Constructs a new virtual context object.
      *
diff --git a/dist/virtuallink.js b/dist/virtuallink.js
index dc4d63a..ccd6c5d 100644
--- a/dist/virtuallink.js
+++ b/dist/virtuallink.js
@@ -5,7 +5,7 @@
  */
 const tslib_1 = require("tslib");
 const types_1 = require("./types");
-const link_1 = (0, tslib_1.__importDefault)(require("./link"));
+const link_1 = tslib_1.__importDefault(require("./link"));
 class VirtualLink extends link_1.default {
     constructor(id, parent) {
         super(id, parent);
diff --git a/dist/virtualnode.js b/dist/virtualnode.js
index d91b4f9..1205bae 100644
--- a/dist/virtualnode.js
+++ b/dist/virtualnode.js
@@ -5,7 +5,7 @@
  */
 const tslib_1 = require("tslib");
 const types_1 = require("./types");
-const node_1 = (0, tslib_1.__importDefault)(require("./node"));
+const node_1 = tslib_1.__importDefault(require("./node"));
 class VirtualNode extends node_1.default {
     constructor(id, parent) {
         super(id, parent);

From adf93a061d4b4a9e99fa01d95cdbea798276acfc Mon Sep 17 00:00:00 2001
From: Gabriela Pinheiro <gpinheiro@ibm.com>
Date: Fri, 1 Jul 2022 14:51:24 -0300
Subject: [PATCH 22/24] undo mend

---
 dist/trail.d.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/dist/trail.d.ts b/dist/trail.d.ts
index 6bb2f2a..1573ca0 100644
--- a/dist/trail.d.ts
+++ b/dist/trail.d.ts
@@ -29,3 +29,4 @@ declare namespace Trail {
 }
 import HKEntity = require("./hkentity");
 import Connector = require("./connector");
+

From a43ca6da12a0078071f7fe8a441bbd057dd8db91 Mon Sep 17 00:00:00 2001
From: Gabriela Pinheiro <gpinheiro@ibm.com>
Date: Mon, 11 Jul 2022 16:51:56 -0300
Subject: [PATCH 23/24] Updated trail from function to class

---
 src/trail.js | 963 +++++++++++++++++++++++++++++++--------------------
 1 file changed, 595 insertions(+), 368 deletions(-)

diff --git a/src/trail.js b/src/trail.js
index 126f96a..969d739 100644
--- a/src/trail.js
+++ b/src/trail.js
@@ -6,462 +6,670 @@
 'use strict'
 
 const {List, Item}    = require('linked-list');
-
-// const shortid   = require('shortid');
 const Types     = require('./types');
 const HKEntity  = require('./hkentity');
 
-
-function Trail (id, actions, parent)
+class Trail extends HKEntity
 {
-
-  if(arguments[0] && typeof arguments[0] === 'object' && isValid(arguments[0]))
-  {
-    let trail = arguments[0];
-
-    this.id = trail.id || null;
-    this.parent = trail.parent || null;
-    this.properties = trail.properties || {};
-    this.metaproperties = trail.metaproperties || {};
-    this.interfaces = trail.interfaces || {};
-    this.actions = trail.actions || new List();
-
-    if (this.actions && Object.keys(this.actions).length > 0) {
-      this.loadActions();
-    }
-  }
-  else
+  /**
+   * Constructs a new trail object.
+   *
+   * @param {string | null} [id] Some id string for this trail. Deprecated: json object, which will deserialized as a Trail.
+   * @param {List<Trail.Action> | Array<string> | null} [actions] Trail actions. 
+   * @param {string | null} [parent] Parent id.
+   */
+
+  constructor(id = null, actions = null, parent = null)
   {
-    this.id = id || null;
-    this.parent = parent || null;
-    this.interfaces = {};
-    this.properties = {};
-    this.metaproperties = {};
+    super();
+
+    /**
+     *
+     * Id of this node. Might be null.
+     *
+     * @public
+     * @type {string | null}
+     *
+     */
+    this.id = id;
+
+    /**
+     * Trail actions. Might be null.
+     *
+     * @public
+     * @type {List<Trail.Action> | Array<string> | null}
+     *
+     */
     this.actions = actions || new List();
 
-  }
+    /**
+     * Parent id. Might be null.
+     *
+     * @public
+     * @type {string | null}
+     *
+     */
+    this.parent = parent;
+
+    /**
+     *  Type of this node.
+     *
+     * @public
+     * @type {string | null}
+     */
+    this.type = Types.TRAIL;
+
+    /**
+     * Interface attributed to this node.
+     *
+     * @public
+     * @type {Object.<string,{type : string, properties : Object.<string, Object>}>}
+     */
+    this.interfaces = {};
 
-  this.type = Types.TRAIL;
-}
+    /**
+     * @public
+     * @type {Object.<string, string | number | Object>
+     */
+    this.properties = {};
 
-Trail.prototype = Object.create (HKEntity.prototype);
-// Trail.prototype = Object.assign(Trail.prototype, List.prototype); // Multiple inheritance with assign
+    /**
+     * @public
+     * @type {Object.<string, string | number | Object>
+     */
+    this.metaproperties = {};
 
+    // TODO: this code seems to copy a trail passed as an id. Create a separate clone/json-deserialize function for that.
+    if(arguments[0] && typeof arguments[0] === 'object' && isValid(arguments[0]))
+    {
+      let trail = arguments[0];
 
-// Update a given action in trail
-Trail.prototype.updateAction = function (oldAction, newAction)
-{
-  oldAction.prepend(newAction);
-  oldAction.detach();
-}
+      this.id = trail.id || null;
+      this.parent = trail.parent || null;
+      this.properties = trail.properties || {};
+      this.metaproperties = trail.metaproperties || {};
+      this.interfaces = trail.interfaces || {};
+      this.actions = trail.actions || new List();
 
-// Add an action to a trail respecting timestamp ordering
-Trail.prototype.addAction = function (action) 
-{
-  var current = this.actions.head;
+      if (this.actions && Object.keys(this.actions).length > 0) {
+        this.loadActions();
+      }
+    }
+  }
+  
+  /**
+   * Update a given action in trail.
+   * 
+   * @param {Trail.Action} oldAction 
+   * @param {Trail.Action} newAction 
+   */
+  updateAction(oldAction, newAction)
+  {
+    oldAction.prepend(newAction);
+    oldAction.detach();
+  }
 
-  while (current)
+  /**
+   * Add an action to a trail respecting timestamp ordering.
+   * 
+   * @param {Trail.Action} action 
+   * @returns {Trail.Action}
+   */ 
+  addAction(action) 
   {
-    if (new Date(current.event['timestamp']) - new Date(action.event['timestamp']))
+    var current = this.actions.head;
+
+    while (current)
     {
-      return current.prepend(action);
+      if (new Date(current.event['timestamp']) - new Date(action.event['timestamp']))
+      {
+        return current.prepend(action);
+      }
+      current = current.next;
     }
-    current = current.next;
-  }
 
-  return this.actions.append(action);
-}
+    return this.actions.append(action);
+  }
 
-// Remove an action from trail using its reference
-Trail.prototype.removeAction = function (action) 
-{
-    var action;
-    if(typeof(action) === 'string') {
-        this.action = this.search(action)
-        
-        //action not found
-        if(!this.action){
-            return
-        }
-    }
-    else { 
-        this.action = action;
-    }
+  /**
+   * Remove an action from trail using its reference.
+   * 
+   * @param {Trail.Action} action 
+   * @returns {Trail.Action}
+   */ 
+  removeAction(action) 
+  {
+      var action;
+      if(typeof(action) === 'string') {
+          this.action = this.search(action)
+          
+          //action not found
+          if(!this.action){
+              return
+          }
+      }
+      else { 
+          this.action = action;
+      }
 
-    this.action.detach();
-}
+      this.action.detach();
+  }
 
-// `append` and `prepend` operations are 
-// handled by our linked list structure
-Trail.prototype.append = function(action)
-{
-  return this.actions.append(action);
-}
+  /**
+   * `append` and `prepend` operations are 
+   * handled by our linked list structure.
+   * 
+   * @param {Trail.Action} action 
+   * @returns {Trail.Action}
+   */ 
+  append(action)
+  {
+    return this.actions.append(action);
+  }
 
-Trail.prototype.prepend = function(action)
-{
-  return this.actions.prepend(action);
-}
+  /**
+   * 
+   * @param {Trail.Action} action 
+   * @returns {Trail.Action}
+   */ 
+  prepend(action)
+  {
+    return this.actions.prepend(action);
+  }
 
-// aliases `in` and `out` represent the input and
-// output TrailNodes for a trail, which conceptually is
-// done through the use of Port elements in Hyperknowledge
-Trail.prototype.in = function(from = null) {
-  if (from)
+  /**
+   * Aliases `in` and `out` represent the input and 
+   * output TrailNodes for a trail, which conceptually is
+   * done through the use of Port elements in Hyperknowledge.
+   * 
+   * @param {Trail.Action | null} from
+   * @returns {Trail.Action}
+   */ 
+  in(from = null)
   {
-    this.actions.head.from = from;
+    if (from)
+    {
+      this.actions.head.from = from;
+    }
+      
+    return this.actions.head.from;
   }
-    
-  return this.actions.head.from;
-}
 
-Trail.prototype.out = function(to = null) {
-  if(this.actions.tail)
+  /**
+   * 
+   * @param {Trail.Action | null} to 
+   * @returns {Trail.Action}
+   */ 
+  out(to = null) 
   {
+    if(this.actions.tail)
+    {
+      if (to)
+      {
+        this.actions.tail.to = to;
+      }
+        
+      return this.actions.tail.to;
+    }
+
     if (to)
     {
-      this.actions.tail.to = to;
+      this.actions.head.to = to;
     }
       
-    return this.actions.tail.to;
+    return this.actions.head.to;
   }
 
-  if (to)
+  /**
+   * 
+   * @returns {number}
+   */ 
+  size()
   {
-    this.actions.head.to = to;
+    if (this.actions.constructor === List)
+    {
+      return this.actions.size;
+    }
+    else if (Array.isArray(this.actions))
+    {
+      return this.actions.length;
+    }
   }
-    
-  return this.actions.head.to;
-}
 
-Trail.prototype.size = function()
-{
-  if (this.actions.constructor === List)
+  /**
+   * 
+   * @param {string} delimiter 
+   * @returns {string}
+   */ 
+  join(delimiter)
   {
-    return this.actions.size;
+      return this.actions.toArray().join(delimiter)
   }
-  else if (Array.isArray(this.actions))
+
+  /**
+   *  Update a given action in the trail.
+   * 
+   * @param {Trail.Action} action
+   * @param {Trail.Action} newAction  
+   */ 
+  //
+  update(action, newAction)
   {
-    return this.actions.length;
+      action.prepend(newAction)
+      action.detach()
   }
-}
 
-Trail.prototype.join = function(delimiter)
-{
-    return this.actions.toArray().join(delimiter)
-}
-
-// Update a given action in the trail
-Trail.prototype.update = function(action, newAction)
-{
-    action.prepend(newAction)
-    action.detach()
-}
-
-// Remove an action from the trail using its reference
-Trail.prototype.remove = function(action)
-{
-    var action
-    if(typeof(action) === 'string') {
-        this.action = this.search(action)
-        
-        //action not found
-        if(!this.action){
-            return
-        }
-    }
-    else { 
-        this.action = action 
-    }
-
-    this.action.detach()
-}
+  /**
+   * Remove an action from the trail using its reference.
+   * 
+   * @param {Trail.Action | string} action 
+   * @returns {Trail.Action | null}
+   */ 
+  // 
+  remove(action)
+  {
+      var action
+      if(typeof(action) === 'string') {
+          this.action = this.search(action)
+          
+          //action not found
+          if(!this.action){
+              return
+          }
+      }
+      else { 
+          this.action = action 
+      }
 
-// Get `num` actions (or the available ones) before `position`
-Trail.prototype.getPrev = function(position, num=1){
-    //check if it is a valid position
-    if (position >= this.actions.size || position <= 1 || this.actions.size <= 1){
-        return;
-    }
+      this.action.detach()
+  }
 
-    // get actions
-    var action = this.actions.toArray()[position]
-    var resultSet = []
-    while(action && action.prev){
-        if (resultSet.length >= num) {
-            if(resultSet.length == 1 && num == 1){
-                return resultSet[0]
-            }
-            return resultSet
-        }
-        else {
-            resultSet.push(action.prev)
-        }
-        
-        action = action.prev
-    }
+  /**
+   * Get `num` actions (or the available ones) before `position`.
+   * 
+   * If a number is not given, 1 is assumed.
+   * 
+   * @param {number} position
+   * @param {number | null} num 
+   * @returns {Array<Trail.Action> | null}
+   */ 
+    getPrev = function(position, num=1)
+    {
+      //check if it is a valid position
+      if (position >= this.actions.size || position <= 1 || this.actions.size <= 1){
+          return;
+      }
 
-    return resultSet
-}
+      // get actions
+      var action = this.actions.toArray()[position]
+      var resultSet = []
+      while(action && action.prev){
+          if (resultSet.length >= num) {
+              if(resultSet.length == 1 && num == 1){
+                  return resultSet[0]
+              }
+              return resultSet
+          }
+          else {
+              resultSet.push(action.prev)
+          }
+          
+          action = action.prev
+      }
 
-// Get `num` actions (or a n<num available ones) after `position`
-// if a number is not given, 1 is assumed
-Trail.prototype.getNext = function(position, num=1){
-    // check if it is a valid position
-    if (position >= this.actions.size || position <= 1 || this.actions.size <= 1){
-        return;
-    }
+      return resultSet
+  }
 
-    // get actions
-    var action = this.actions.toArray()[position]
-    var resultSet = []
-    while(action && action.next){
-        if (resultSet.length >= num) {
-            if(resultSet.length == 1 && num == 1){
-                return resultSet[0]
-            }            
-        }
-        else {
-            resultSet.push(action.next)
-        }
-        
-        action = action.next
-    }
+  /**
+   * Get `num` actions (or a n<num available ones) after `position`.
+   * 
+   * If a number is not given, 1 is assumed.
+   * 
+   * @param {number} position
+   * @param {number | null} num 
+   * @returns {Array<Trail.Action> | null}
+   */
+  getNext(position, num=1)
+  {
+      // check if it is a valid position
+      if (position >= this.actions.size || position <= 1 || this.actions.size <= 1){
+          return;
+      }
 
-    return resultSet
-}
+      // get actions
+      var action = this.actions.toArray()[position]
+      var resultSet = []
+      while(action && action.next){
+          if (resultSet.length >= num) {
+              if(resultSet.length == 1 && num == 1){
+                  return resultSet[0]
+              }            
+          }
+          else {
+              resultSet.push(action.next)
+          }
+          
+          action = action.next
+      }
 
-// Get the position of an action in the list,
-// it might be useful for pagination. Returns 
-// -1 in case action is not found in the list
-Trail.prototype.getPositionOf = function(action){
-    //search action by eventId
-    var array = this.actions.toArray();
-    for (var i = 0; i < this.actions.size; i++) {
-        if(array[i].event["id"] == action.event["id"]){
-            return i;
-        }
-    }
-    return -1;
-}
+      return resultSet
+  }
 
-// Get an action at specified position
-// a position = 0 is equivalent to trail.head
-Trail.prototype.getActionAt = function(position) {
-    //check if it is a valid position
-    if (position < 0 || position >= this.actions.size ){
-        return;
-    }
+  /**
+   * Get the position of an action in the list,
+   * it might be useful for pagination. 
+   * 
+   * Returns -1 in case action is not found in the list.
+   * 
+   * @param {Trail.Action} action 
+   * @returns {number}
+   */ 
+
+  getPositionOf(action)
+  {
+      //search action by eventId
+      var array = this.actions.toArray();
+      for (var i = 0; i < this.actions.size; i++) {
+          if(array[i].event["id"] == action.event["id"]){
+              return i;
+          }
+      }
+      return -1;
+  }
 
-    //return action by position in array
-    return this.actions.toArray()[position]
-}
+  /**
+   * Get an action at specified position.
+   * 
+   * Position = 0 is equivalent to trail.head.
+   * 
+   * @param {number} position
+   * @returns {Trail.Action}
+   */ 
+  getActionAt(position) 
+  {
+      //check if it is a valid position
+      if (position < 0 || position >= this.actions.size ){
+          return;
+      }
 
-// Search for action(s) either by an event identifier or by filters
-Trail.prototype.search = function(eventId = null, filters){        
-    if (!filters && eventId instanceof String) {
-        filters = {'from': null, 'fromAnchor': 'lambda', 'to': null, 'toAnchor': 'lambda'}
-    }
-    else if (!filters && eventId instanceof Object){
-        filters = eventId
-        eventId = null
-    }
-    
-    // nothing to be found
-    if (!eventId && !filters['from'] && !filters['to']){
-        return
-    }
+      //return action by position in array
+      return this.actions.toArray()[position]
+  }
 
-    // search actions by eventId
-    var array = this.actions.toArray();
-    if (eventId){
-        for (var i = 0; i < this.actions.size; i++) {
-            if(array[i].event["id"] == eventId){
-                return array[i];
-            }
-        }
-        return;
-    }
+  /**
+   * Search for action(s) either by an event identifier or by filters.
+   * 
+   * @param {Object | string | null} eventId
+   * @param {Object} filters
+   * @return {Array<Trail.Action> | null}
+   */ 
+  search(eventId = null, filters)
+  {        
+      if (!filters && eventId instanceof String) {
+          filters = {'from': null, 'fromAnchor': 'lambda', 'to': null, 'toAnchor': 'lambda'}
+      }
+      else if (!filters && eventId instanceof Object){
+          filters = eventId
+          eventId = null
+      }
+      
+      // nothing to be found
+      if (!eventId && !filters['from'] && !filters['to']){
+          return
+      }
 
-    // search actions by filters
-    var resultSet = []
-    for (var i = 0; i < this.actions.size; i++) {
-        if((filters['from'] && filters['to']) && array[i].from == filters['from'] && array[i].to == filters['to']){
-            resultSet.push(array[i])
-        }
-        else if(array[i].from == filters['from'] || array[i].to == filters['to']){
-            resultSet.push(array[i])
-        }
-    }
-    return resultSet
-}
+      // search actions by eventId
+      var array = this.actions.toArray();
+      if (eventId){
+          for (var i = 0; i < this.actions.size; i++) {
+              if(array[i].event["id"] == eventId){
+                  return array[i];
+              }
+          }
+          return;
+      }
 
-Trail.prototype.loadActions = function (actions = null)
-{
+      // search actions by filters
+      var resultSet = []
+      for (var i = 0; i < this.actions.size; i++) {
+          if((filters['from'] && filters['to']) && array[i].from == filters['from'] && array[i].to == filters['to']){
+              resultSet.push(array[i])
+          }
+          else if(array[i].from == filters['from'] || array[i].to == filters['to']){
+              resultSet.push(array[i])
+          }
+      }
+      return resultSet
+  }
 
-  // use array of actions if passed
-  if(actions && Array.isArray(actions))
+  /**
+   * 
+   * @param {Array<Trail.Action> | null} actions 
+   * @return {List<Trail.Action> | null}
+   */ 
+  loadActions(actions = null)
   {
-    if(actions[0].event.timestamp)
+
+    // use array of actions if passed
+    if(actions && Array.isArray(actions))
     {
-      this.actions = new List(...sort(actions));
-    }
-    else {
-      this.actions = new List(...actions);
+      if(actions[0].event.timestamp)
+      {
+        this.actions = new List(...sort(actions));
+      }
+      else {
+        this.actions = new List(...actions);
+      }
+      return this.actions;
     }
-    return this.actions;
-  }
 
-  let actionArray = []
-  let actionIds = []
-  for (let i in this.actions) 
-  {
-    // create Action object from json object
-    if (this.actions[i] && this.actions[i].hasOwnProperty("from") && 
-    this.actions[i].hasOwnProperty("to") && 
-    this.actions[i].hasOwnProperty("agent") &&
-    this.actions[i].hasOwnProperty("event"))
+    let actionArray = []
+    let actionIds = []
+    for (let i in this.actions) 
     {
-      let from = new TrailNode(this.actions[i].from.nodeId, this.actions[i].from.nodeType, this.actions[i].from.targetAnchor);
-      let to = new TrailNode(this.actions[i].to.nodeId, this.actions[i].to.nodeType, this.actions[i].to.targetAnchor);
-      let event = { "id": this.actions[i].event.id, "type": this.actions[i].event.type, "properties": this.actions[i].event.properties, "timestamp": new Date(this.actions[i].event.timestamp)};
-      let agent = this.actions[i].agent;
+      // create Action object from json object
+      if (this.actions[i] && this.actions[i].hasOwnProperty("from") && 
+      this.actions[i].hasOwnProperty("to") && 
+      this.actions[i].hasOwnProperty("agent") &&
+      this.actions[i].hasOwnProperty("event"))
+      {
+        let from = new TrailNode(this.actions[i].from.nodeId, this.actions[i].from.nodeType, this.actions[i].from.targetAnchor);
+        let to = new TrailNode(this.actions[i].to.nodeId, this.actions[i].to.nodeType, this.actions[i].to.targetAnchor);
+        let event = { "id": this.actions[i].event.id, "type": this.actions[i].event.type, "properties": this.actions[i].event.properties, "timestamp": new Date(this.actions[i].event.timestamp)};
+        let agent = this.actions[i].agent;
 
-      actionArray.push(new Action({from, to, event, agent}));
-    }
-    else if(this.actions[i] && this.actions[i].hasOwnProperty("event") && this.actions[i].event.hasOwnProperty("timestamp"))
-    {
-      // we got event's id and timestamp
-      actionArray.push(new Action({event: {"id": i, "timestamp": new Date(this.actions[i].event.timestamp)}}));
+        actionArray.push(new Action({from, to, event, agent}));
+      }
+      else if(this.actions[i] && this.actions[i].hasOwnProperty("event") && this.actions[i].event.hasOwnProperty("timestamp"))
+      {
+        // we got event's id and timestamp
+        actionArray.push(new Action({event: {"id": i, "timestamp": new Date(this.actions[i].event.timestamp)}}));
+      }
+      else if(Array.isArray(this.actions))
+      {
+        // all we got is an Array with the event's id
+        actionIds.push(this.actions[i]);
+      }
+      else 
+      {
+        // all we got is event's id
+        actionIds.push(i);
+      }
     }
-    else if(Array.isArray(this.actions))
+    
+    // sort action items before creating list
+    if (actionArray.length > 0)
     {
-      // all we got is an Array with the event's id
-      actionIds.push(this.actions[i]);
+      this.actions = new List(...sort(actionArray));
     }
-    else 
+    else if (actionIds.length > 0)
     {
-       // all we got is event's id
-       actionIds.push(i);
+      this.actions = actionIds;
     }
   }
-  
-  // sort action items before creating list
-  if (actionArray.length > 0)
-  {
-    this.actions = new List(...sort(actionArray));
-  }
-  else if (actionIds.length > 0)
-  {
-    this.actions = actionIds;
-  }
-}
 
-function isValid(entity)
-{
-  let isValid = false;
-  if (entity && typeof (entity) === 'object' && !Array.isArray(entity))
+  /**
+   * 
+   * @param {Object} entity 
+   * @returns {boolean}
+   */ 
+  static isValid(entity)
   {
-    if (entity.hasOwnProperty('type') && entity.type === Types.TRAIL &&
-        entity.hasOwnProperty('id') && entity.hasOwnProperty('parent'))
+    let isValid = false;
+    if (entity && typeof (entity) === 'object' && !Array.isArray(entity))
     {
-      isValid = true;
+      if (entity.hasOwnProperty('type') && entity.type === Types.TRAIL &&
+          entity.hasOwnProperty('id') && entity.hasOwnProperty('parent'))
+      {
+        isValid = true;
+      }
     }
-  }
 
-  return isValid;
-}
+    return isValid;
+  }
 
-function sort(actions = null)
-{
-  if (actions && Array.isArray(actions) && actions[0].event.timestamp.constructor === Date)
+  /**
+   * 
+   * @param {Array<Object> | null} actions 
+   * @returns {Array<Object>} 
+   */ 
+  static sort(actions = null)
   {
-    // sort and return object array based on timestamp
-    return actions.sort(function(action1, action2)
+    if (actions && Array.isArray(actions) && actions[0].event.timestamp.constructor === Date)
     {
-      return action1.event['timestamp'] - action2.event['timestamp'];
-    });
-  }
-  else if (actions && Array.isArray(actions) && (actions[0].event.timestamp.constructor === String || actions[0].event.timestamp.constructor === Number))
-  {
-    // sort Action array based on timestamp
-    return actions.sort(function(action1, action2)
+      // sort and return object array based on timestamp
+      return actions.sort(function(action1, action2)
+      {
+        return action1.event['timestamp'] - action2.event['timestamp'];
+      });
+    }
+    else if (actions && Array.isArray(actions) && (actions[0].event.timestamp.constructor === String || actions[0].event.timestamp.constructor === Number))
     {
-      return new Date(action1.event['timestamp']) - new Date(action2.event['timestamp']);
-    });
+      // sort Action array based on timestamp
+      return actions.sort(function(action1, action2)
+      {
+        return new Date(action1.event['timestamp']) - new Date(action2.event['timestamp']);
+      });
+    }
   }
-}
 
-Trail.prototype.toJSON = function ()
-{
-  let actionArray = [];
-
-  if (this.actions.constructor === List)
+  /**
+   * 
+   * @returns {Object.<string,any>}
+   * 
+   */ 
+  toJSON()
   {
-    //in case we have only action ids and timestamps
-    if(this.actions.head && (!this.actions.head.from && !this.actions.head.to && !this.actions.head.agent))
-    {
-      let action = this.actions.head;
+    let actionArray = [];
 
-      while(action)
+    if (this.actions.constructor === List)
+    {
+      //in case we have only action ids and timestamps
+      if(this.actions.head && (!this.actions.head.from && !this.actions.head.to && !this.actions.head.agent))
       {
-        actionArray.push(action.id);
-        action = action.next;
+        let action = this.actions.head;
+
+        while(action)
+        {
+          actionArray.push(action.id);
+          action = action.next;
+        }
+      }
+      else {
+        actionArray = this.actions.toArray();
       }
     }
-    else {
-      actionArray = this.actions.toArray();
+    else if (Array.isArray(this.actions))
+    {
+      actionArray = this.actions;
     }
-  }
-  else if (Array.isArray(this.actions))
-  {
-    actionArray = this.actions;
-  }
-
-  return {
-    id: this.id,
-    parent: this.parent,
-    properties: this.properties,
-    metaproperties: this.metaproperties,
-    interfaces: this.interfaces,
-    actions: actionArray,
-    type: this.type
-  }; 
-}
 
-Trail.prototype.serialize = function ()
-{
-  let actions;
-  if(this.actions instanceof Array)
-  {
-    actions = this.actions;
-  }
-  else
-  {
-    actions = this.actions.toArray();
-  }
-
-  return {
+    return {
       id: this.id,
       parent: this.parent,
       properties: this.properties,
       metaproperties: this.metaproperties,
       interfaces: this.interfaces,
-      actions: actions,
+      actions: actionArray,
       type: this.type
-  };
-}
+    }; 
+  }
+
+  /**
+   * 
+   * @returns {Object.<string,any>} 
+   */ 
+  serialize()
+  {
+    let actions;
+    if(this.actions instanceof Array)
+    {
+      actions = this.actions;
+    }
+    else
+    {
+      actions = this.actions.toArray();
+    }
 
+    return {
+        id: this.id,
+        parent: this.parent,
+        properties: this.properties,
+        metaproperties: this.metaproperties,
+        interfaces: this.interfaces,
+        actions: actions,
+        type: this.type
+    };
+  }
+}
 
-// TrailNode is basically an envelope for a hknode and a target anchor
-class TrailNode {
-  constructor(nodeId, nodeType, targetAnchor) {
+/**
+ * TrailNode is basically an envelope for a hknode and a target anchor.
+ */
+Trail.TrailNode = class TrailNode
+ {
+  /**
+   *  Constructs a new Trail object.
+   *
+   * @param {string} [nodeId] Some id string for this TrailNode. 
+   * @param {string} [nodeType] Type of the TrailNode.
+   * @param {string} [targetAnchor]
+   */
+  constructor(nodeId, nodeType, targetAnchor) 
+  {
+    /**
+     *
+     * Id of this TrailNode.
+     *
+     * @public
+     * @type {string}
+     *
+     */
     this.nodeId = nodeId;
+
+    /**
+     *
+     * Type of this TrailNode.
+     *
+     * @public
+     * @type {string}
+     *
+     */
     this.nodeType = nodeType;
+
+    /**
+     * @public
+     * @type {string}
+     */
     this.targetAnchor = targetAnchor;
   }
 
-  toString() {
+  /**
+   *
+   * @return {string}
+   */
+  toString()
+  {
       return this.nodeId + "#" + this.targetAnchor;
   }
 
@@ -470,10 +678,18 @@ class TrailNode {
   // }
 }
 
-// actions hold references to source and destination trail 
-// nodes (along with their respective target anchors), 
-// the related event and an agent (user, system or content).
-class Action extends Item {
+/**
+ * actions hold references to source and destination trail
+ * nodes (along with their respective target anchors), 
+ * the related event and an agent (user, system or content).
+ */
+Trail.Action = class Action extends Item
+ {
+  /** Constructs a new Action object.
+   *
+   * @param {Object<{from: Trail.Action | null, to: Trail.Action | null, event: Object | null, agent: string | null}>}
+   * 
+   */
   constructor({from = null, to = null, event = {}, agent = null} = {}) 
   {
       super();
@@ -501,11 +717,19 @@ class Action extends Item {
       }
   }
 
+  /**
+   * 
+   * @returns {number} 
+   */
   getTime()
   {
       return new Date(this.event['timestamp']).getTime();
   }
 
+  /**
+   * 
+   * @returns {string} 
+   */
   toString() 
   {
     if(this.from && this.to && this.agent && this.event && this.event.id )
@@ -518,6 +742,10 @@ class Action extends Item {
     }
   }
 
+  /**
+   * 
+   * @returns {Object.<string,any>} 
+   */
   toJSON() 
   {
     if(this.from && this.to && this.agent && this.event && this.event.id )
@@ -532,9 +760,8 @@ class Action extends Item {
 }
 
 Trail.type = Types.TRAIL;
-Trail.isValid = isValid;
-Trail.sort = sort;
-Trail.Action = Action;
-Trail.TrailNode = TrailNode;
-
+const isValid = Trail.isValid;
+const sort = Trail.sort;
+const Action = Trail.Action;
+const TrailNode = Trail.TrailNode;
 module.exports = Trail;

From c8e1c1f1362049bbe874e26876ce7e34c68daf80 Mon Sep 17 00:00:00 2001
From: Gabriela Pinheiro <gpinheiro@ibm.com>
Date: Tue, 19 Jul 2022 18:13:20 -0300
Subject: [PATCH 24/24] edited linked-list import

---
 package.json | 2 +-
 src/trail.js | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/package.json b/package.json
index 3820d7c..ba28f46 100644
--- a/package.json
+++ b/package.json
@@ -53,7 +53,7 @@
     "request": "^2.88.0",
     "request-promise-native": "^1.0.8",
     "shortid": "^2.2.14",
-    "linked-list": "file:src/linked-list"
+    "linked-list": "3.0.2"
   },
   "license": "MIT",
   "repository": {
diff --git a/src/trail.js b/src/trail.js
index 969d739..d23e156 100644
--- a/src/trail.js
+++ b/src/trail.js
@@ -5,7 +5,7 @@
 
 'use strict'
 
-const {List, Item}    = require('linked-list');
+import {List, Item}  from 'linked-list';
 const Types     = require('./types');
 const HKEntity  = require('./hkentity');