wendu-worker-js

A lightweight Wendu Worker Typescript/Javascript lib for polling the Wendu Orchestration API

Worker Implementation

A worker is a micro-server that performs a task for the Wendu Orchestration engine. A woker should be implemented in the following pattern

1. Register the TaskDefinition with a unique task name this worker performs. Task name should be lowercase with alpha-numerica chars and dashes. For example: copy-file
2. The worker should periodically (interval) poll (GET) the API for tasks in the queue.
3. Once a worker gets a task via polling it should immediately acknowledge (POST) it has received the task. An un-acked task will get requed for other workers.
4. The worker should perform the unique task/work as necessary
5. Once completed (success or failed) the result should be reported (POST) back to the API.

Installation

Install with

npm install wendu-worker-js

How to Use the Client

Create a client

Create and reuse this client. It uses https://github.com/microsoft/typed-rest-client/ under the hood for HTTP calls.

const opts: WenduApiOptions = {
	url: `http://localhost:1331`,
	pollInterval: 5*1000,
	workerIdentity: 'worker-joe',
};

const client = new WenduApiClient(opts);

Register a Task Definition

• async register(taskDef: TaskDef): Promise<TaskDef>

await client.register({
			name: 'hello-world',
			timeoutPolicy: 'RETRY',
			timeoutSeconds: 5,
			retryLogic: 'FIXED',
			retryCount: 1,
			inputKeys: ['name', 'language'],
			outputKeys: ['greeting'],
			inputTemplate: {}
		});

Poll for Tasks

• async poll(taskName: string, total: number): Promise<Task[] | null>

const tasks = await client.poll('move-file', 10);

Acknowledge a Task has been Received

• async ack(task: { taskId: string }): Promise<boolean>

const acked = await client.ack(t);

Post Task Completion Results

• async postResult(result: TaskResult): Promise<TaskResult>

const result: TaskResult = {
  status: 'COMPLETED',
  taskId: t.taskId,
  output: {
	 filePath: '//fileshare/temp/newfile.mp3'
  },
  logs: ['INFO: Moving file']
 };

await client.postResult(result);

Example Client Code

See example in /test subfolder

Getting Started: Writing a NodeJS Typescript Worker

1. Create a new directory
2. Use Node 10.8. nvm use 10.8.0
3. Run npm init
4. Run tsc --init (tsc > 3.0.3)

Use the following tsconfig.json options:

{ "compilerOptions": {
    "target": "es6",
    "module": "commonjs",
    "moduleResolution": "node",
    "typeRoots": [ "node_modules/@types" ]
}

5. Run npm install --save-dev @types/node
6. Run npm install --save-dev debug
7. Run npm install --save wendu-worker-test
8. Write a new worker with a new/unique task def
9. Compile and run with tsc && DEBUG=wendu node index.js