Usando o Camunda para orquestração conveniente com base no REST e no Workflow Engine (sem Java)

Olá Habr! Apresento a sua atenção a tradução do artigo "Use Camunda como um mecanismo de orquestração e fluxo de trabalho baseado em REST fácil de usar (sem tocar em Java)", de Bernd Rücker.

07.07.2020, tradução do artigo de Bernd Rücker

, Java: C#, Node.JS/JavaScript Golang. , , -, Saga .

BPM- Camunda . — . , , «» Camunda Java-. , Java. ?

! , Camunda - Java , . :

• ;
• REST API;
• , Java;
• C # Node.JS;
• Camunda (Docker Tomcat).

Camunda Java Java (JVM). Camunda REST API, , , REST Camunda:

Camunda BPMN, XML-. Camunda Modeler.

Camunda Docker

Camunda — Docker. Camunda .

:

  docker run -d -p 8080:8080 camunda/camunda-bpm-platform:latest

Linux, Java Tomcats. Dockerfiles (, ) Github.

Camunda Enterprise Edition, Dockerfile.

Camunda Docker : Tomcat, . - , Docker- Tomcat, , , .

, Saga , . BPMN :

REST API . , trip.bpmn Camunda Docker, localhost: 8080:

  curl -w "\n" \
-H "Accept: application/json" \
-F "deployment-name=trip" \
-F "enable-duplicate-filtering=true" \
-F "deploy-changed-only=true" \
-F "trip.bpmn=@trip.bpmn" \
http://localhost:8080/engine-rest/deployment/creat

REST API , :

  curl \
-H "Content-Type: application/json" \
-X POST \
-d '{"variables":{"someData" : {"value" : "someValue", "type": "String"}},"businessKey" : "12345"}}' \
http://localhost:8080/engine-rest/<!-- -->process-definition/key/<!-- -->FlowingTripBookingSaga<!-- -->/start

: Camunda , ? Camunda (Push-Principle), , . worker REST, Camunda (Pull-Principle).

, fetchAndLock ( worker ):

  curl \
-H "Content-Type: application/json" \
-X POST \
-d <!-- -->'{"workerId":"worker123","maxTasks":1,"usePriority":true,"topics":[{"topicName": "reserve-car"}, "lockDuration": 10000, "variables": ["someData"]}]}'<!-- --> \
http://localhost:8080/engine-rest/external-task/fetchAndLock

Camunda, worker ( , external task, ):

  curl \
-H "Content-Type: application/json" \
-X POST \
-d <!-- -->'{"workerId":"worker123", "variables": {}}'<!-- --> \
http://localhost:8080/engine-rest/<!-- -->external-task/EXTERNAL_TASK_ID/complete

— Java, ? !

REST API . JavaScript JQuery, C# — System.Net.Http Newtonsoft.Json. . - .

:

• JavaScript: . Camunda;
• Java: . Camunda;
• C#: . , ;
• PHP: — API , , .

JavaScript Java, Camunda. , REST API Camunda. , , , REST API Camunda. .

C#

, :

  var camunda = new CamundaEngineClient("http://localhost:8080/engine-rest/engine/default/", null, null);
  // Deploy the BPMN XML file from the resources
  camunda.RepositoryService.Deploy("trip-booking", new List<object> {
        FileParameter.FromManifestResource(Assembly.GetExecutingAssembly(), "FlowingTripBookingSaga.Models.FlowingTripBookingSaga.bpmn")
     });
  
  // Register workers
  registerWorker("reserve-car", externalTask => {
    // here you can do the real thing! Like a sysout :-)
    Console.WriteLine("Reserving car now...");
    camunda.ExternalTaskService.Complete(workerId, externalTask.Id);
  });
  registerWorker("cancel-car", externalTask => {
    Console.WriteLine("Cancelling car now...");
    camunda.ExternalTaskService.Complete(workerId, externalTask.Id);
  });
  registerWorker("book-hotel", externalTask => {
    Console.WriteLine("Reserving hotel now...");
    camunda.ExternalTaskService.Complete(workerId, externalTask.Id);
  });
  // Register more workers...
  
  StartPolling();
  
  string processInstanceId = camunda.BpmnWorkflowService.StartProcessInstance("FlowingTripBookingSaga", new Dictionary<string, object>()
    {
      {"someBookingData", "..." }
    });

: . .

Node.js

  var Workers = require('camunda-worker-node');
  var workers = Workers('http://localhost:8080/engine-rest', {
    workerId: 'some-worker-id'
  });
  
  workers.registerWorker('reserve-car', [ 'someData' ], function(context, callback) {
    var someNewData = context.variables.someData + " - added something";
    callback(null, {
      variables: {
        someNewData: someNewData
      }
    });
  });
  
  workers.shutdown();

github.com

Camunda

Docker «Camunda standalone WAR»

Docker Camunda Tomcat (, Docker Tomcat), Camunda WAR-.

Java, Camunda Standalone war. Maven : Maven war Maven Overlay.

Camunda Tomcat

— Camunda Tomcat, . Java Runtime Environment (JRE), . .

- , Tomcat, . , Tomcat , . Google , .

Camunda Tomcat

— Tomcat Camunda, . Tomcat, , , , Windows.

Camunda

, - Camunda. Camunda , , — : REST API . , .

Como você deve ter notado, é muito fácil começar a usar o Camunda, independentemente do idioma que você está usando. O ponto principal é que toda a comunicação é feita através da API REST. A instalação também é bastante fácil, principalmente ao usar o Docker.