Camunda Team Blog

Camunda NodeJS External Task Client 0.1.1 Released

Written by Seif Eddine Ghezala on , under Execution category.

We recently published the first alpha release of camunda-external-task-client-js, an NPM module that makes it possible to handle your BPMN Service Tasks in NodeJS.

Today, a new alpha release is ready, bringing up major features that revolve around easily exchanging process variables between Service Tasks and the Workflow Engine.

The feature set includes:

  • Accessing single/all variables
  • Creating/Updating single or multiple variables
  • Support for primitive (e.g. Integer) and complex variable types (e.g. JSON)

Let’s walk through a basic example to showcase some of these features:

Example

A Workflow for Granting Loans

A Workflow for Granting Loans

1. Running Camunda

First, make sure to have Camunda running.

2. Deploying the Workflow

Download the following model and deploy it using the Camunda Modeler.

3. Installing the NPM package

Install camunda-external-task-client-js from npm using:

npm install -s camunda-external-task-client-js

Or:

yarn add camunda-external-task-client-js

4. Consuming Service Tasks in NodeJS

const { Client, logger } = require('camunda-external-task-client-js');

// configuration for the Client:
//  - 'baseUrl': url to the Workflow Engine
//  - 'logger': utility to automatically log important events
const config = { baseUrl: 'http://localhost:8080/engine-rest', use: logger };

// create a Client instance with custom configuration
const client = new Client(config);

// create a handler for the task
const handler = async({ task, taskService }) => {
  // get task variable 'defaultScore'
  const defaultScore = task.variables.get('defaultScore');

  // set task variable 'creditScores'
  task.variables.set('creditScores', [defaultScore, 9, 1, 4, 10]);

  // complete the task
  try {
    await taskService.complete(task);
    console.log('I completed my task successfully!!');
  } catch (e) {
    console.error(`Failed completing my task, ${e}`);
  }
};

// susbscribe to the topic 'creditScoreChecker' & provide the created handler
client.subscribe('creditScoreChecker', handler);

The output should be:

polling
✓ subscribed to topic creditScoreChecker
polling
✓ polled 10 tasks
✓ completed task 897ce191-2dea-11e8-a9c0-66b11439c29a

Documentation & More Detailed Examples

The main goal of this post is to show a basic usage of the new alpha release of camunda-external-task-client-js. To find out about the full range of features, you can check the documenation or a more in-depth example.

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