Integrate GLSP WebSocketServerLauncher with NestJS Gateway

[giuliano-marinelli]

Hello there,

I'm currently trying to integrate GLSP Server with NestJS framework.
The way I found to use it fast was just making a NestJS service that use onModuleInit() method to launch the GLSP Server with the WebSocketServerLauncher and the inversify Container.

Here is my code:

import { Inject, Injectable, OnModuleInit } from '@nestjs/common';

import {
  ServerModule,
  SocketLaunchOptions,
  WebSocketServerLauncher,
  createAppModule,
  createSocketCliParser,
  defaultLaunchOptions
} from '@eclipse-glsp/server/node';

import { Container } from 'inversify';

import { SomeService } from 'src/some/some.service';

import { MyDiagramModule } from '../my-glsp/diagram/my-diagram-module';

@Injectable()
export class GLSPService implements OnModuleInit {
  constructor(@Inject(SomeService) private readonly someService: SomeService) {}

  onModuleInit() {
    this.launch().catch((error) => console.error('Error in GLSP server:', error));
  }

  async launch() {
    // define container options
    const options = createSocketCliParser<SocketLaunchOptions>({
      ...defaultLaunchOptions,
      port: 3001,
      host: '127.0.0.1'
    }).parse();

    // create a new inversify container
    const container = new Container();

    // load a new GLSP app module
    container.load(createAppModule(options));

    // define NestJS services that can be used in the GLSP diagram module
    const services = {
      someService: this.someService
    };

    // create a GLSP Server Module with the Diagram Module (this will use a custom server module and diagram module for my diagram language support)
    const serverModule = new ServerModule().configureDiagramModule(new MyDiagramModule(services));

    // create a new WebSocketServerLauncher
    const launcher = container.resolve(WebSocketServerLauncher);

    // configure the server module and start the server
    await launcher.configure(serverModule);
    await launcher.start({ port: options.port, host: options.host, path: 'glsp' });
  }
}

But, the problems start when I want to communicate MyDiagramModule with other services of my NestJS server. I can use them by directly calling them, but can't get user related information throw the NestJS guards from the WebSocket messages (actions / operations of GLSP).

Is there a way to integrate WebSocketServerLauncher with the Gateways of NestJS? So in this way the flow of messages sended and received by the WebSocket can pass throw NestJS workflow.

Which other ways to integrate GLSP with NestJS are there?

Thanks, cheers.

[martin-fleck-at]

Hi @giuliano-marinelli. Unfortunately, I'm not really familiar with the NestJS framework but what exactly do you mean by:

but can't get user related information throw the NestJS guards from the WebSocket messages (actions / operations of GLSP).

Is there a particular error that you are receiving?

As you can see the WebSocketServerLauncher implementation wraps most of the lower level communication with a createWebSocketConnection call where reader and writer take care of the concrete messages, maybe the integration makes more sense there. But as I mentioned, unfortunately I don't know NestJS well enough to give a more educated advise.

[giuliano-marinelli]

Thanks for the answer!
I found that it's not possible to integrate it directly into the NestJS workflow because both GLSP and NestJS use Containers, which instantiate their own classes. If I decorate the WebSocketLauncher with both @Injectable decorators, it will create one instance in each framework's containers.

Anyway, my problem was not that. Instead, I was trying to communicate the GLSP Server with my NestJS services to get the models from the database and needed to authenticate in some way.
Finally, I solved this by making custom Client Sessions in which I add authentication data sent from ws at the 'sec-websocket-protocol', and then make custom WebSocketServerLauncher and GLSPServer which send this authentication data in the Actions for use in the handlers.

Thanks for the advice, it really helped me to understand how the Web Socket connection is created in the GLSP framework.