Node-Service

This is the service handler side of the SOA: : Working Example

Prequisites ( standard AMQP 0-9-1 )

• AMQP Server/Cluster accepting connections with credentials. ( see Local setup )
• Gateway Service(s)/Cluster(s) listening on responseTopic with CorrelationID. (@donsky/node-gateway )

Impliments:

• NodeJS
• AVRO Message Standards & Schema ( dependancy: avsc )
• AMQP 0-9-1 Communication Standard ( dependancy: amqplib )
• Babel 7 & ESNext plugins ( dependancy: babel-* )

Initialize Your Service

import Service from "@donsky/node-service"

new Service(/* { ...actions } */)

Configure

All of the following configurations must be handled in the env vars, or in config in the code. Examples below:

ENV VARS

Add the following to your bashrc, or bash profile depending on environment. I use docker-compose so I just attach them to the container environment. These will be picked up automatically by the default config file.

export HOSTNAME=consumerService
export MQ_PROTOCOL=amqp
export MQ_HOSTNAME=rabbitmq
export MQ_PORT=5672
export MQ_USERNAME=defaultAdmin
export MQ_PASSWORD=SomePassword
export MQ_QUEUE=consumerTopic

The hostname can be a URI or a local hostname, in this example, 'rabbitmq' is my docker container hostname. During deploy this would change and be environment specific.

Code

Service.configure({
  mq:{
    username: "defaultAdmin",
    password: "somePassword"
    hostname: "rabbitmq"
    port    : 5672,
    queue   : "consumerTopic"
  }
})

Action Object Options:

// action.js
import dep1 from "Dep1"

export const consumerActionName = {
  lambda: async function ( { firstName } ) {
    const lastName = await dep1()
    return { response: lastName }
  },
  requestAVRO : [
    { name: "firstName", type: "string" }
  ],
  responseAVRO: [
    { name: "response", type: "string" }
  ]
}

Events:

• Error: See what's in the error variables for more detail, like so: serv.on( "error", err => console.log( err ) )
• Connected Successfully connected to the message queue server serv.on( "connected", () => console.log( "Service Connected to MQ" ) )
• Ready: App is ready and listening on the topic serv.on( "ready", topic => console.log( "All Ready: ", topic ))

Example:

"use strict"

import Service from "@donsky/node-service"
import * as actions from "./action"

Service.configure( { mq: { queue: "consumerTopic" } } )
const svc = new Service( actions )
svc.on( "error", error => console.error( error ) )
svc.on( "connected", () => console.log( "Connected" ) )
svc.on( "reconnecting", () => console.log( "...reconnecting" ) )
svc.on( "ready", () => console.log( "Service is ready" ) )

Notes:

• Without any actions and responders the server should start, but it won't do much
• This works well with PM2 (Process Manager 2)

Local:

May I recommend spinning up a docker environment for those prerequisites, and getting all the services talking:

# Note: I use a docker container
version: "3.8"
services:
  rabbitmq:
    image: rabbitmq:management
    ports:
     - "5672:5672"
     - "15672:15672"
    environment:
      # ${ENV_VAR} work here for values as well
      RABBITMQ_DEFAULT_USER: defaultAdmin
      RABBITMQ_DEFAULT_PASS: SomePassword
    restart: on-failure   

  service-auth:
    build:
      context: ./
    environment:
      - MQ_PROTOCOL=amqp
      - MQ_HOSTNAME=rabbitmq
      - MQ_PORT=5672
      - MQ_USERNAME=defaultAdmin
      - MQ_PASSWORD=SomePassword
      - MQ_QUEUE=consumerTopic
    depends_on:
      - rabbitmq
    restart: on-failure