@kronos-integration/service

Base service implementation

Service states

stateDiagram-v2
    stopped --> starting [1]
    starting --> failed: [2]
    starting --> running: [3]
    running --> stopping: [4]
    running --> failed: [5]
    stopping --> failed: [6]
    stopping --> stopped: [7]

Loading

The transitions are:

Number	From	To	Condition
1	~stopped~	~starting~
2	~starting~	~failed~
3	~starting~	~running~
4	~running~	~stopping~
5	~running~	~failed~
6	~stopping~	~failed~
7	~stopping~	~stopped~

API

Table of Contents

• EndpointsMixin
  • Parameters
• endpoints
• ServiceConfig
  • Properties
  • configFor
    • Parameters
  • clearPreserved
    • Parameters
  • configureValue
    • Parameters
  • configure
    • Parameters
  • autostart
  • name
• merge
  • Parameters
• defineServiceConsumerProperties
  • Parameters
• ServiceLogger
  • logEntry
    • Parameters
  • autostart
  • name
  • endpoints
• Service
  • Parameters
  • Properties
  • extendetName
  • stateChanged
    • Parameters
  • rejectWrongState
    • Parameters
  • timeoutForTransition
    • Parameters
  • _start
  • _stop
  • _restart
  • restartIfRunning
  • toStringAttributes
  • isServiceProvider
  • toString
  • toJSONWithOptions
    • Parameters
  • name
  • autostart
  • _configure
    • Parameters
  • configure
    • Parameters
  • getCredential
    • Parameters
  • getCredentials
    • Parameters
  • storePersistentCredentials
  • log
    • Parameters
  • attributes
  • endpoints
• StandaloneServiceProvider
  • name

EndpointsMixin

Endpoint accessor mixin. Manages endpoints in a container.

Parameters

• superclass

endpoints

Default set of endpoints to create.

Returns Object {} empty set

ServiceConfig

Extends Service

Config providing service. Dispatches config requests to services. Also preserves them until a maching service becomes avaliable.

Properties

• preservedConfigs Map<string, Object> values for services not already established

configFor

Deliver configuration for a given service.

Parameters

• name string service name
• config Object

Returns Promise<Object>

clearPreserved

Forget about preserved config of a service.

Parameters

• name string service name

configureValue

Set config entry.

Parameters

• key string path to the value
• value any

configure

Parameters

• config (Array | Object)

autostart

We always start immediate.

Returns boolean true

name

Returns string 'config'

merge

Merge from b into a. When a and b are arrays of values only the none duplicates are appendend to a.

Parameters

• a any
• b any

Returns any merged b into a

defineServiceConsumerProperties

Assign services based on a configuration.

Parameters

• target Object object
• config Object service defintion
• provider Object service provider
• waitUntilFactoryPresent boolean

ServiceLogger

Extends Service

Log receiving service.

logEntry

Parameters

• entry Object

  • entry.severity string

autostart

We always start immediate.

Returns boolean true

name

Returns string 'logger'

endpoints

Adds a log input endpoint to the set of Service endpoints.

Returns Object predefined endpoints

Service

Extends EndpointsMixin(StateTransitionMixin(LogLevelMixin(class {}), prepareActions({ start: { stopped: rsfDefault }, restart: { stopped: rsfDefault, running: { target: "running", during: "restarting", timeout } }, stop: { running: ssfDefault, starting: ssfDefault, failed: ssfDefault } }), "stopped"))

Service The initial state is 'stopped'. All services have at least three endpoints:

• log out: log events
• config in: configuration request
• command in: administrative actions to be executed by the step

Parameters

• config Object
• ic InitializationContext

Properties

• endpoints Object

extendetName

Used in human readable state messages. Besides the actual service name it may contain additional short hints.

Returns string

stateChanged

Called when the service state changes. Emits a serviceStateChanged event to the owner.

Parameters

• origin any
• oldState string
• newState string

rejectWrongState

Called when state transition is not allowed.

Parameters

• action string originating action name

• Throws any always

timeoutForTransition

Deliver transition timeout.

Parameters

• transition Object

Returns number milliseconds before throwing for a long running transition

_start

Opens all endpoint connections.

_stop

Closes all endpoint connections.

_restart

Restart action. default implementation does a _stop() and a _start()

Returns Promise<any> fulfills after start

restartIfRunning

Restarts if in running mode. Otherwise does nothing.

Returns Promise<any> resolves when restart is done (or immediate if no restart triggered)

toStringAttributes

Mapping of properties used in toString.

Returns Object

isServiceProvider

Base service is not a provider.

Returns boolean false

toString

Returns the string representation of this service.

Returns string human readable name

toJSONWithOptions

Deliver json representation.

Parameters

• options Object

  • options.includeRuntimeInfo boolean include runtime informtion like state
  • options.includeDefaults boolean include default endpoints
  • options.includeName boolean include name of the service
  • options.includeConfig boolean include config attributes
  • options.includePrivate boolean include private config attributes

Returns Object json representation

name

Defaults to the type.

Returns string type

autostart

Should we start when beeing registered.

Returns boolean false

_configure

Takes attribute values from config parameters and copies them over to the object. Copying is done according to attributes. Which means we loop over all configuration attributes. and then for each attribute decide if we use the default, call a setter function or simply assign the attribute value.

Parameters

• config Object

Returns Set<string> of modified attributes

configure

Use new configuration. Internally calls _configure(config) as the constructor does. If attribute with needsRestart are touched the restartIfRunning method will be called.

Parameters

• config Object

Returns Promise<undefined> fillfills when config is applied

getCredential

Parameters

• key string

Returns Promise<(string | Uint8Array)>

getCredentials

Retrieve all (filtered) credential attribute values.

Parameters

• filter Function (optional, default (name,attribute)=>attribute.credential)

Returns Promise<Object>

storePersistentCredentials

Load and store persistent credentials in the service attributes.

Returns Promise<undefined>

log

Adds service name to the log event.

Parameters

• level string the log level
• arg Object log content

attributes

Meta information for the config attributes.

• default optional default value of the attribute
• needsRestart optional modification requires a service restart
• setter(newValue,attribute) optional function to be used if simple value assignment is not enough The Service class only defines the logLevel, and start/stop/restart timeout attribute

Returns Object

endpoints

Definition of the predefined endpoints.

• log out
• config in

Returns Object predefined endpoints

StandaloneServiceProvider

Extends ServiceProviderMixin(Service)

Simple service manager (for examples and testing only).

name

Returns string 'standalone-provider'

install

With npm do:

npm install @kronos-integration/service

license

BSD-2-Clause