@vicgrk/messenger

Send message and response to event with ts decorators

Before start

This library use a rabbitmq instance to communicate. You can spin up a developpment message broker with docker using:

docker run -d --rm --name my-rabbit -p 15672:15672 -p 5672:5672 rabbitmq:3-management

In a production environment, we recommand using a replicated RabbitMQ cluster.

Installation

Warning, this package is not a DI manager and use other Dependency Injection manager to function properly. You can run this library with:

• typedi
• TSED api environment

The author will try to add support for new depency injectors in the futures.

You can install the package with just

npm i --save @vicgrk/messenger

Documentation

You can start the amqp lib by initializing the Messenger singleton

TypeDI

Init your Messenger in the entrypoint of your app (index.ts) :

import Container, { Service } from "typedi";
import { Messenger } from "@vicgrk/messenger";

Messenger.init({
  rootDir: __dirname,
  name: "my-node-name",
  verbose: process.env.NODE_ENV !== "production",
  rabbit: {
    host: process.env.RABBITMQ_HOST,
    port: process.env.RABBITMQ_PORT,
    user: process.env.RABBITMQ_USER,
    password: process.env.RABBITMQ_PASSWORD,
  },
  di: Container,
});

TSED.io

For tsed, you can init your Messenger in your main configuration

import { AfterInit } from "@tsed/common";
import { Configuration, Inject, InjectorService } from "@tsed/di";
import { Messenger } from "@vicgrk/messenger";

@Module()
export class Server implements AfterInit {
  @Inject()
  private injector: InjectorService;

  $afterInit() {
    Messenger.init({
      rootDir: __dirname,
      name: "my-node-name",
      verbose: process.env.NODE_ENV !== "production",
      rabbit: {
        host: process.env.RABBITMQ_HOST,
        port: process.env.RABBITMQ_PORT,
        user: process.env.RABBITMQ_USER,
        password: process.env.RABBITMQ_PASSWORD,
      },
      di: this.injector,
    });
  }
}

Configuration

Library configuration object

| Name | Default | Description | | ------- | ---------------------- | ---------------------------------------------------------------------------------------- | | rabbit | see below the defaults | The rabbitmq credentials used to connect to the server | | di | undefined | The di service usued in this package. | | name | undefined | The service name of your application, usued to receive message from other services | | verbose | false | Logs every transactions and payloads | | rootDir | undefined | The root directory where you implement your @Amqp decorators (get folder and subfolders) |

RabbitMQ configuration object

| Name | Default | Description | | -------- | --------- | ----------------------------------------- | | host | localhost | The IP or hostname of the rabbitmq server | | port | 5672 | The port of the rabbitmq server | | user | guest | The user of the rabbitmq server | | password | guest | The password of the rabbitmq server |

How to use

To emit to rabbitmq

import { Messenger } from "@vicgrk/messenger";

@Service()
export class MyService {
  async getMemberInformation(memberId: string) {
    const member = await Messenger.invoke<{ user: string }>(
      "payment.member-informations",
      {
        memberId,
      }
    );
    // you should receive an object from the payment service running in a different application.
  }

  // If you just send data, without receiving anything, you can call the publish method. It's much smaller in compute requirements (avoid the round trip)
  sendUserUpdate(user: unknown) {
    Messenger.publish("users.update-user", user);
  }

  // If you want to, for example, refresh a list on all available consumers, you can you the broadcast method
  broadcastListenerService(user: unknown) {
    Messenger.broadcast("users.add-user-listener", user);
  }
}

Now, this is how to receive and response to events :

In your payment service, just use the @Amqp decorarator

// first, import your mesh service
import { Amqp, Message, Origin } from "@vicgrk/messenger";

@Service()
export class MyService {
  constructor(private db: Database) {}

  // Get the raw payload sent from `MyService`
  @Amqp("member-informations")
  async getMemberInformation(@Message() payload: { memberId: string }) {
    const member = await this.db.getUserFromId(payload);
    return member;
  }

  // Get a specific property from the sent message
  @Amqp("member-informations")
  async getMemberInformation(@Message("memberId") payload: string) {
    const member = await this.db.getUserFromId(payload);
    return member;
  }

  // You can also get the instance that send the request (this is the name parameter of the service that sent the request)
  @Amqp("member-informations")
  async getMemberInformation(
    @Message("memberId") payload: string,
    @Origin() origin: string
  ) {
    const member = await this.db.getUserFromId(payload);
    return member;
  }
}