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@stomp/ng2-stompjs

An Angular (Angular2, Angular4, ...) style wrapper for an updated stompjs, originally developed by Jeff Mesnil.

Compatibility

The code itself is quite clean and should work with any setup Angular2 and above. However, packaging as an NPM module has been proven to be clumsy. So, the NPM module may not work with every possible setup. In case it does not work for your setup, please raise a ticket. As interim you may include all the .ts files from https://github.com/stomp-js/ng2-stompjs/tree/master/src and place these in your project directly.

Tested with Angular2 (2.4.0) and Angular4 (4.0.0) project created with Angula CLI.

Installation

To install this library, run:

$ npm install @stomp/ng2-stompjs --save

or, if using yarn

$ yarn add @stomp/ng2-stompjs

This will addtionally install @stomp/stompjs from https://github.com/stomp-js/stomp-websocket

Usage

Prerequisites

  • You will need to have a Stomp broker running.
  • Sample code on this page assumes you have RabbitMQ running with default settings and Web STOMP plugin activated. (see: https://www.rabbitmq.com/web-stomp.html).

All the Hard Work

  • The main service is StompService, which will need to be provided.
  • The STOMP Broker connection details will need to be provided via another class StompConfigService. Typically you will subclass it to provide configuration. See https://angular.io/docs/ts/latest/guide/dependency-injection.html for background reading.
  • Sample config:
const conf: StompConfig= {
    // Which server?
    url: "ws://127.0.0.1:15674/ws",

    user: "guest",
    pass: "guest",

    // How often to heartbeat?
    // Interval in milliseconds, set to 0 to disable
    heartbeat_in: 0, // Typical value 0 - disabled
    heartbeat_out: 20000, // Typical value 20000 - every 20 seconds

    // Wait in milliseconds before attempting auto reconnect
    // Set to 0 to disable
    // Typical value 5000 (5 seconds)
    reconnect_delay: 5000,

    // Will log diagnostics on console
    debug: true
}
  • Your ConfigService must extend StompConfigService and implement a method public get(): Observable<StompConfig>. Example:
  public get(): Observable<StompConfig> {
    const conf: StompConfig= {
      // as from previous example
    };

    return Observable.of(conf);
  }
  providers: [
    StompService,
    {
      provide: StompConfigService,
      useClass: ConfigService
    }
  ]

Reap the Benefits

Inject StompService

In your constructor (typically of a component or a service), inject StompService as a dependency:

constructor(private _stompService: StompService) { }

Subscribe to a queue

The queue name structure and semantics vary based on your specific STOMP Broker, see: https://www.rabbitmq.com/stomp.html for RabbitMQ specific details.

Call subscribe with name of the queue which returns an Observable. Any of Observable specific operators (map, filter, subscribe, etc.) cane be applied on it. This can also be set into a template with async pipe.

Example:

    let stomp_subscription = this._stompService.subscribe('/topic/ng-demo-sub');

    stomp_subscription.map((message: Message) => {
      return message.body;
    }).subscribe((msg_body: string) => {
      console.log(`Received: ${msg_body}`);
    });

The Message class comes from @stomp/stompjs. So, you will need the following import in the classes where you consume messages:

import {Message} from '@stomp/stompjs';

Unsubscribe from a queue

Not a likely chance that you would need it.

You will need to unsubscribe from stomp_subscription (which is an Observer), it will then internally unsubscribe from the underlying STOMP queue subscription.

Publishing messages

Call public publish(queueName: string, message: string). Example:

this._stompService.publish('/topic/ng-demo-sub', 'My important message');

Please note that message is actually string. So, if you need to send JSON you will need to convert it into string (typically using JSON.stringify())

Watching for Stomp Connection status

  • stompService.state is a BehaviorSubject which maintains and switches its value as per the underlying Stomp Connection status.
  • The value is from an enum with these possible values: CLOSED, TRYING, CONNECTED, and DISCONNECTING.
  • The following code will subscribe to stompService.state and covert the enum value (which is a number) to the corresponding string value:
    this._stompService.state
      .map((state: number) => StompState[state])
      .subscribe((status: string) => {
      console.log(`Stomp connection status: ${status}`);
    });

Development

After checking out, install the dependencies:

$ npm install

or, if using yarn

$ yarn

It uses ngc to build.

$ npm run build

To lint all *.ts files:

$ npm run lint

To publish it uses a shell script which copies, a slightly modified, package.json into dist/ folder and publishes only the dist/ folder.

$ bin/npm-publish

Contributors

License

MIT