Feathers.js and background jobs, how to trigger service event (or realtime update clients)

Question

Looking a bit through the feathers docs I understood that is based on services and hooks and that services have the events that also help to offer realtime sync between server and client.

As long as things are simple, as in docs I understand, basically having a service generated and then adding/saving/updating using the service methods will triggeer the event.

My scenario is a bit different:

• The API endpoint does not return info from a table but complex queries based on multiple tables
• I need to have background workers that do operations on the database,probably using Kue (if there's no better way inside feathers), when a worker finishes the job, I need to have a way to trigger the API service so it updates the clients with the new data.

How can I do this in feathers?

Answer 1

Both scenarios can be handled with Feathers like this:

Feathers services do not have to be tied to a table. You can implement a custom service just like you would in any other framework (controller). It is not uncommon to create Dashboard services that aggregates different service calls or uses service.Model to access the ORM you are using directly:

class MyService {
  find(params) {
    const userModel = this.app.service('users').Model;
    const invoiceModel = this.app.service('invoices').Model;

    return userModel.doSomething()
      .then(data => invoiceModel.doSomethingElse());
  }

  setup(app, path) {
    this.app = app;
  }
}

Background workers should also be using the Feathers API (in Node this can be done by either using the application directly via const app = require('./src/app') or connecting transparently through Feathers as the client) so that all connected clients will get updates automatically. Then there should be no need to trigger events manually (which comes with caveats like having to also run your raw data through any hooks that change the data).