WIP: review

.mvn/extensions.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<extensions>
+    <extension>
+        <groupId>io.takari.polyglot</groupId>
+        <artifactId>polyglot-yaml</artifactId>
+        <version>0.3.2</version>
+    </extension>
+</extensions>
+

.travis.yml

@@ -0,0 +1,3 @@
+language: java
+jdk: openjdk11
+script: mvn clean verify

Procfile

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+web: java $JAVA_OPTS -p ./target/parallel-java-1.0.jar:./target/dependency -m nl.jqno.paralleljava/nl.jqno.paralleljava.Main

README.md

@@ -0,0 +1,13 @@
+# Parallel Java
+
+[![Build Status](https://img.shields.io/travis/jqno/paralleljava.svg?style=plastic)](https://travis-ci.org/jqno/paralleljava)
+
+This app is written in Java from a Parallel Universe where annotations were never invented. You can check: there isn't a single annotation in this codebase!
+
+It requires a JDK 11 to build and run.
+
+It's a showcase for my talk, Java from a Parallel Universe. It's also a fully functioning [Todo Backend](https://www.todobackend.com/) (you can [run the Todo Backend test suite](https://www.todobackend.com/specs/index.html?https://parallel-java.herokuapp.com/todo
+)!), using the [Spark web framework](http://sparkjava.com/), the [Jdbi database framework](http://jdbi.org/), and **no framework** for dependency injection because you really really don't need one. It also uses Java 11 `var` declarations, [Vavr](http://www.vavr.io/) and [Polyglot for Maven](https://github.com/takari/polyglot-maven) because I think they're pretty nifty and because they make the code look a little different, as if, I dunno, as if it came from a Parallel Universe or something? Also, the application is fully modularized and has 100% test coverage because why not.
+
+Note, however, that this is still a demo app that is not production-ready. Some corners have definitely been cut. For example, the [InMemoryRepository](https://github.com/jqno/paralleljava/blob/master/src/main/java/nl/jqno/paralleljava/app/persistence/inmemory/InMemoryRepository.java) is not thread-safe.
+

checkstyle.xml

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+<?xml version="1.0"?>
+<!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.3//EN" "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
+
+<module name = "Checker">
+    <property name="charset" value="UTF-8"/>
+    <property name="severity" value="error"/>
+
+    <module name="TreeWalker">
+        <module name="Regexp">
+            <property name="format" value="@"/>
+            <property name="illegalPattern" value="true"/>
+            <property name="ignoreComments" value="true"/>
+            <property name="message" value="Annotations are not allowed!"/>
+        </module>
+    </module>
+</module>

pom.yml

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+modelVersion: 4.0.0
+groupId: nl.jqno.paralleljava
+artifactId: parallel-java
+version: 1.0
+packaging: jar
+
+name: parallel-java
+description: "Todo-Backend built with Java from a Parallel Universe: a demo project to illustrate the point of my talk 'Java from a Parallel Universe'"
+
+properties: {
+  encoding: utf-8,
+  maven.compiler.source: 11,
+  maven.compiler.target: 11,
+  coverage.threshold: 1.0
+}
+
+repositories:
+  - { id: bintray-jqno-picotest-repo, url: "https://dl.bintray.com/jqno/picotest-repo" }
+
+dependencyManagement:
+  dependencies:
+    - { groupId: org.jdbi, artifactId: jdbi3-bom, version: 3.6.0, type: pom, scope: import }
+
+dependencies:
+  - { groupId: io.vavr, artifactId: vavr, version: 0.10.0 }
+  - { groupId: io.vavr, artifactId: vavr-gson, version: 0.10.0 }
+  - { groupId: com.sparkjava, artifactId: spark-core, version: 2.7.2 }
+  - { groupId: org.slf4j, artifactId: slf4j-api, version: 1.7.26 }
+  - { groupId: org.slf4j, artifactId: slf4j-simple, version: 1.7.26 }
+  - { groupId: com.google.code.gson, artifactId: gson, version: 2.8.5 }
+  - { groupId: org.jdbi, artifactId: jdbi3-core }
+  - { groupId: org.jdbi, artifactId: jdbi3-vavr }
+  - { groupId: org.postgresql, artifactId: postgresql, version: 42.2.5 }
+  - { groupId: com.h2database, artifactId: h2, version: 1.4.199 }
+
+  - { groupId: nl.jqno.picotest, artifactId: picotest, version: 0.3, scope: test }
+  - { groupId: nl.jqno.equalsverifier, artifactId: equalsverifier, version: 3.1.7, scope: test }
+  - { groupId: org.assertj, artifactId: assertj-core, version: 3.11.1, scope: test }
+  - { groupId: org.assertj, artifactId: assertj-vavr, version: 0.1.0, scope: test }
+  - { groupId: com.tngtech.archunit, artifactId: archunit, version: 0.9.3, scope: test }
+
+  # REST-Assured is useful but problematic on Java 11. We need to overrule Groovy and exclude JAXB-OSGI.
+  - { groupId: org.codehaus.groovy, artifactId: groovy, version: 2.5.6, scope: test }
+  - { groupId: org.codehaus.groovy, artifactId: groovy-xml, version: 2.5.6, scope: test }
+  - groupId: io.rest-assured
+    artifactId: rest-assured
+    version: 3.3.0
+    scope: test
+    exclusions:
+      - groupId: com.sun.xml.bind
+        artifactId: jaxb-osgi
+
+build:
+  plugins:
+    - groupId: org.apache.maven.plugins
+      artifactId: maven-compiler-plugin
+      version: 3.8.0
+
+    - groupId: org.apache.maven.plugins
+      artifactId: maven-surefire-plugin
+      version: 2.22.1
+      configuration:
+        argLine: "@{argLine} --add-opens nl.jqno.paralleljava/nl.jqno.paralleljava.app.domain=ALL-UNNAMED"
+
+    - groupId: org.apache.maven.plugins
+      artifactId: maven-dependency-plugin
+      version: 3.1.1
+      configuration:
+        includeScope: runtime
+      executions:
+        - id: default
+          phase: package
+          goals: [copy-dependencies]
+
+    - groupId: org.apache.maven.plugins
+      artifactId: maven-checkstyle-plugin
+      version: 3.0.0
+      dependencies:
+        - { groupId: com.puppycrawl.tools, artifactId: checkstyle, version: 8.18 }
+      configuration:
+        configLocation: checkstyle.xml
+        includeTestSourceDirectory: true
+        encoding: UTF-8
+        consoleOutput: true
+        excludes: "**/module-info.java"
+      executions:
+        - id: default
+          phase: verify
+          goals: [check]
+          configuration:
+            failsOnError: true
+
+    - groupId: org.jacoco
+      artifactId: jacoco-maven-plugin
+      version: 0.8.3
+      configuration:
+        excludes:
+          - "nl/jqno/paralleljava/Main.class"
+      executions:
+        - id: default-prepare-angent
+          goals: [prepare-agent]
+        - id: default-report
+          goals: [report]
+        - id: default-check
+          goals: [check]
+          configuration:
+            rules:
+              - element: BUNDLE
+                limits:
+                  - counter: INSTRUCTION
+                    value: COVEREDRATIO
+                    minimum: ${coverage.threshold}

scripts/deploy

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+#!/usr/bin/env bash
+
+git push -f heroku master

scripts/jacoco

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+#!/usr/bin/env bash
+
+mvn clean verify
+mvn jacoco:report
+open target/site/jacoco/index.html
+

scripts/logs

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+#!/usr/bin/env bash
+
+heroku logs --tail --source app
+

src/main/java/module-info.java

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+module nl.jqno.paralleljava {
+    exports nl.jqno.paralleljava;
+
+    opens nl.jqno.paralleljava.app.domain to gson;
+
+    requires io.vavr;
+    requires io.vavr.gson;
+    requires jdbi3.core;
+    requires jdbi3.vavr;
+    requires java.sql; // required for gson
+    requires gson;
+    requires slf4j.api;
+    requires spark.core;
+}

src/main/java/nl/jqno/paralleljava/Main.java

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+package nl.jqno.paralleljava;
+
+import io.vavr.collection.HashMap;
+import nl.jqno.paralleljava.app.Runner;
+import nl.jqno.paralleljava.app.controller.DefaultController;
+import nl.jqno.paralleljava.app.environment.Environment;
+import nl.jqno.paralleljava.app.environment.HerokuEnvironment;
+import nl.jqno.paralleljava.app.logging.LoggerFactory;
+import nl.jqno.paralleljava.app.logging.Slf4jLogger;
+import nl.jqno.paralleljava.app.persistence.RandomIdGenerator;
+import nl.jqno.paralleljava.app.persistence.database.DatabaseRepository;
+import nl.jqno.paralleljava.app.persistence.database.JdbiEngine;
+import nl.jqno.paralleljava.app.persistence.database.TodoMapper;
+import nl.jqno.paralleljava.app.serialization.GsonSerializer;
+import nl.jqno.paralleljava.app.server.SparkServer;
+
+public class Main {
+    public static void main(String... args) {
+        LoggerFactory loggerFactory = c -> new Slf4jLogger(org.slf4j.LoggerFactory.getLogger(c));
+
+        var processBuilder = new ProcessBuilder();
+        var environmentMap = HashMap.ofAll(processBuilder.environment());
+        var environment = new HerokuEnvironment(environmentMap);
+
+        var fullUrl = environment.hostUrl().getOrElse(Environment.DEFAULT_URL) + Environment.ENDPOINT;
+        var port = environment.port().getOrElse(Environment.DEFAULT_PORT);
+        var jdbcUrl = environment.jdbcUrl().getOrElse(Environment.DEFAULT_JDBC_URL);
+
+        var todoMapper = new TodoMapper(fullUrl);
+        var dbEngine = new JdbiEngine(jdbcUrl, todoMapper, loggerFactory);
+        var repository = new DatabaseRepository(dbEngine);
+
+        var idGenerator = new RandomIdGenerator();
+        var serializer = GsonSerializer.create(loggerFactory);
+        var controller = new DefaultController(fullUrl, repository, idGenerator, serializer, loggerFactory);
+        var server = new SparkServer(Environment.ENDPOINT, port, controller, loggerFactory);
+
+        var runner = new Runner(repository, server, loggerFactory);
+        runner.startup();
+    }
+}

src/main/java/nl/jqno/paralleljava/app/Runner.java

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+package nl.jqno.paralleljava.app;
+
+import nl.jqno.paralleljava.app.logging.Logger;
+import nl.jqno.paralleljava.app.logging.LoggerFactory;
+import nl.jqno.paralleljava.app.persistence.Repository;
+import nl.jqno.paralleljava.app.server.Server;
+
+public class Runner {
+    private final Repository repository;
+    private final Server server;
+    private final Logger logger;
+
+    public Runner(Repository repository, Server server, LoggerFactory loggerFactory) {
+        this.repository = repository;
+        this.server = server;
+        this.logger = loggerFactory.create(getClass());
+    }
+
+    public void startup() {
+        repository.initialize()
+                .onSuccess(ignored -> {
+                    printBanner();
+                    server.run();
+                });
+    }
+
+    private void printBanner() {
+        logger.forProduction(" _   _         _____                                            _    _ __ _ _");
+        logger.forProduction("| \\ | | ___   |  ___| __ __ _ _ __ ___   _____      _____  _ __| | _| |\\ \\ \\ \\");
+        logger.forProduction("|  \\| |/ _ \\  | |_ | '__/ _` | '_ ` _ \\ / _ \\ \\ /\\ / / _ \\| '__| |/ / | \\ \\ \\ \\");
+        logger.forProduction("| |\\  | (_) | |  _|| | | (_| | | | | | |  __/\\ V  V / (_) | |  |   <|_|  ) ) ) )");
+        logger.forProduction("|_| \\_|\\___/  |_|  |_|  \\__,_|_| |_| |_|\\___| \\_/\\_/ \\___/|_|  |_|\\_(_) / / / /");
+        logger.forProduction("=======================================================================/_/_/_/");
+        logger.forProduction(" :: Built with Plain Java! ::                                          \uD83C\uDF89");
+    }
+}

src/main/java/nl/jqno/paralleljava/app/controller/Controller.java

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+package nl.jqno.paralleljava.app.controller;
+
+import io.vavr.control.Try;
+
+public interface Controller {
+    Try<String> get();
+    Try<String> get(String id);
+    Try<String> post(String json);
+    Try<String> patch(String id, String json);
+    Try<String> delete();
+    Try<String> delete(String id);
+}

src/main/java/nl/jqno/paralleljava/app/controller/DefaultController.java

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+package nl.jqno.paralleljava.app.controller;
+
+import io.vavr.Function1;
+import io.vavr.control.Try;
+import nl.jqno.paralleljava.app.domain.Todo;
+import nl.jqno.paralleljava.app.logging.Logger;
+import nl.jqno.paralleljava.app.logging.LoggerFactory;
+import nl.jqno.paralleljava.app.persistence.IdGenerator;
+import nl.jqno.paralleljava.app.persistence.Repository;
+import nl.jqno.paralleljava.app.serialization.Serializer;
+
+import java.util.UUID;
+
+public class DefaultController implements Controller {
+    private final String url;
+    private final Repository repository;
+    private final IdGenerator idGenerator;
+    private final Serializer serializer;
+    private final Logger logger;
+
+    public DefaultController(String url, Repository repository, IdGenerator idGenerator, Serializer serializer, LoggerFactory loggerFactory) {
+        this.url = url;
+        this.repository = repository;
+        this.idGenerator = idGenerator;
+        this.serializer = serializer;
+        this.logger = loggerFactory.create(getClass());
+    }
+
+    public Try<String> get() {
+        return repository.getAll()
+                .map(serializer::serializeTodos);
+    }
+
+    public Try<String> get(String id) {
+        var uuid = serializer.deserializeUuid(id);
+        if (uuid.isEmpty()) {
+            return Try.failure(new IllegalArgumentException("Invalid GET request: " + id));
+        }
+
+        return repository
+                .get(uuid.get())
+                .flatMap(o -> o.map(serializer::serializeTodo).toTry(() -> new IllegalArgumentException("Cannot find " + id)));
+    }
+
+    public Try<String> post(String json) {
+        logger.forProduction("POSTed: " + json);
+        var partialTodo = serializer.deserializePartialTodo(json);
+        if (partialTodo.isEmpty() || partialTodo.get().title().isEmpty()) {
+            return Try.failure(new IllegalArgumentException("Invalid POST request: " + json));
+        }
+
+        var pt = partialTodo.get();
+        var id = idGenerator.generateId();
+        var todo = new Todo(id, pt.title().get(), buildUrlFor(id), false, pt.order().getOrElse(0));
+        return repository.create(todo)
+                .map(ignored -> serializer.serializeTodo(todo));
+    }
+
+    public Try<String> patch(String id, String json) {
+        logger.forProduction("PATCHed: " + json);
+        var uuid = serializer.deserializeUuid(id);
+        var partialTodo = serializer.deserializePartialTodo(json);
+        if (uuid.isEmpty() || partialTodo.isEmpty()) {
+            return Try.failure(new IllegalArgumentException("Invalid PATCH request: " + id + ", " + json));
+        }
+
+        var pt = partialTodo.get();
+        Function1<Todo, Todo> updater = todo -> new Todo(
+                todo.id(),
+                pt.title().getOrElse(todo.title()),
+                todo.url(),
+                pt.completed().getOrElse(todo.completed()),
+                pt.order().getOrElse(todo.order())
+        );
+        return repository.update(uuid.get(), updater)
+                .map(serializer::serializeTodo);
+    }
+
+    public Try<String> delete() {
+        return repository.deleteAll()
+                .map(ignored -> "");
+    }
+
+    public Try<String> delete(String id) {
+        var uuid = serializer.deserializeUuid(id);
+        if (uuid.isEmpty()) {
+            return Try.failure(new IllegalArgumentException("Invalid DELETE request: " + id));
+        }
+
+        return repository.delete(uuid.get())
+                .map(ignored -> "");
+    }
+
+    private String buildUrlFor(UUID id) {
+        return url + "/" + id.toString();
+    }
+}