rpc-module

Module that provide you with a possibility to communicate with other modules of your system via rpc

Getting started

What is RPC?

RPC stands for "remote procedure call". Using such tool you can invoke function that is not part of your application. For example, you can make a call to another microservice if you're using such arhictecture.

Usage

First you need to install it into your project:

npm i -S @nazar910/rpc-module

Decide what communication transport you need (at the moment it is only AMQP, but I'm gonna implement other transports):

• AMQP:

npm i -S amqplib

Now you can simply require and use it (see also AMQP example in the tests):

const rpcModule = require('@nazar910/rpc-module');
const { AMQPRPCClient, AMQPRPCServer } = rpcModule.getDriver('amqp');

const RABBITMQ_URI = 'amqp://localhost:5672';
async function main() {
    const server = AMQPRPCServer.create(RABBITMQ_URI);
    await server.start();
    server.addHandler('important', (job) => `"${job}" is very important`);

    const client = AMQPRPCClient.create(RABBITMQ_URI);
    const result = await client.call('important', 'doing something');
    console.log(result);
}

main();

API

1. rpcModule.getDriver(driverName: string) Returns apropriate drivers (Server and Client) for specified driverName.

const rpcModule = require('@nazar910/rpc-module');
const { AMQPRPCServer, AMQPRPCClient } = rpcModule.getDriver('amqp');

2. Drivers API

!Note: all driver have similar API for easy usage.

• create(driverArgs)

AMQPRPCServer and AMQPRPCClient have create factory method for getting instance of driver (rpcServer or rpcClient). Example:

const rpcModule = require('@nazar910/rpc-module');
const { AMQPRPCServer, AMQPRPCClient } = rpcModule.getDriver('amqp');
const RABBITMQ_URI = 'amqp://localhost:5672';
const rpcServer = AMQPRPCServer.create(RABBITMQ_URI);
const rpcClient = AMQPRPCClient.create(RABBITMQ_URI);

• start()

rpcServer and rpcClient have start method for ensuring connection. Required for server to start listening before registering handlers. Example:

// ...
async function () {
    await rpcServer.start();
    await rpcClient.start();
}
// ...

• rpcServer.addHandler(command: string, job: Function)

rpcServer has addHandler method for registering handlers. Command is the name of rpc procedure and handler should be a function that returns Promise (or async function) and result will be sent to client. !!!Note: it is important to call rpcServer.start() before registering handlers. Example:

// ...
async function handler(...args) {
    console.log('Args are', args);
    return args;
}
async function () {
    await rpcServer.addHandler('foo', handler);
}
// ...

• rpcClient.call

rpcClient has call(command: string, arg1, arg2, ..., argn) method for calling rpc. Command is the name of rpc procedure and args are arguments to be passed to rpc. Example:

// ...
async function () {
    const result = await rpcClient.call('foo', 'bar');
    console.log('Result is', result);
}
// ...

• rpcClient.sendRaw

rpcClient has sendRaw(queueName: string, data: object) method for just sending msg to a queue. Example:

// ...
async function () {
    await rpcClient.sendRaw('some-queue', {foo: 'bar'});
}
// ...