Communication

The communication is a feature and an entity that is responsible for communication between [[environments|runtime.entities.environment]].

This mechanism is responsible for [[services|runtime.entities.service]] to be available in the environments in which the service is not provided from.

Each time a service declares that it's with the allowRemoteAccess [[runtime.entities.service#^remote_access]] a proxy is created in every other environment, which will trigger the callMethod method of the communication instance, and will call the service on the remote environment.

For communication between two environments to work, they need to establish a communication protocol. Basically, what is needed to be done is to tell the current communication instance how to send messages to the communication instance of the other environment.

The @wixc3/engine-core package exports [[runtime.entities.communication.initializers]], which are responsible for establishing a connection between engine environments, when using engineer

So let's say we have an engine application with two environments declared an exported from the f1 feature declaration file

import { COM } from '@wixc3/engine-core';

export const browserEnv = new Environment('main', 'window', 'single');
export const serverEnv = new Environment('server', 'node', 'single');

export default new Feature({
  id: 'f1',
  api: {
    echoService: Service.withType<{ echo(): string }>().providedFrom(serverEnv),
  },
  dependencies: [COM],
});

In this point, if we use engineer cli, we can just use the __ API to establish a connection between the main and server environments, in the main environment setup

import { socketClientInitializer } from '@wixc3/engine-core';
import f1, { browserEnv, serverEnv } from './f1.feature';

f1.setup(browserEnv, ({ echoService }, { COM: { communication } }) => {
  socketClientInitializer({ communication, env: serverEnv });
  echoService.echo().then(console.log).catch(console.error);
});

From this point in time, a connection is established between the two environments, and they can call each other's services.

Full list of the provided initializers.