@pestras/micro-nats NPM

Pestras Micro Nats

Pestras microservice plugin for nats messaging server support.

install

npm i @pestras/micro @pestras/micro-nats

Plug In

import { SERVICE, Micro } from '@pestras/micro';
import { MicroNats } from '@pestras/micro-nats';

Micro.plugins(new MicroNats());

@SERVICE()
class test {}

Micro.start(Test);

MicroNats class accepts a single optional argument connection.

Name	Type	Default	Description
connection	string \| number \| NatsConnectionOptions	'localhost:4222'	see Nats Docs

SUBJECT DECORATOR

Used to subscribe to nats server pulished subjects, and also accepts a subject string as a first argument and an optional config object.

Name	Type	Default	Description
hooks	string[]	[]	hooks methods that should be called before the route handler
dataQuota	number	1024 * 100	Subject msg data size limit
payload	Nats.Payload	Payload.JSON	see Nats Docs
options	Nats.SubscriptionOptions	null	see Nats Docs
meta	any	extra details that will be passed to the handler, useful for multiple subjects

import { SERVICE, Micro } from '@pestras/micro';
import { SUBJECT, NatsMsg } from '@pestras/micro-nats';
import { Client, Payload} from 'ts-nats';

Micro.plugins(new MicroNats());

@SERVICE({ workers: 3 })
class Email {
  
  async auth(nats: Client, msg: NatsMsg, handlerName: string) {
    // if hook failed its purpose should check for msg reply if exists and return false
    if (msg.reply) {
      nats.publish(msg.replay, { error: 'some error' })
      return false
    }

    // otherwise
    return true;
  }

  @SUBJECT('user.insert', {
    hooks: ['auth'],
    options: { queue: 'emailServiceWorker' }
  })
  sendActivationEmail(nats: Client, msg: NatsMsg) {
    let auth = msg.data.auth;
  }

Hooks must return or resolve (async) to true on success or false on failure.

Multible Subjects

Multible subjects can be used on the same handler.

import { SERVICE, Micro } from '@pestras/micro';
import { SUBJECT, NatsMsg } from '@pestras/micro-nats';
import { Client, Payload} from 'ts-nats';

Micro.plugins(new MicroNats());

interface MsgInput { id: string; email: string }

@SERVICE()
class Email {

  @SUBJECT('emails.new', { meta: { template: "newEmail" } })
  @SUBJECT('emails.reactivate', { meta: { template: "reactivateEmail" } })
  sendActivataionEmail(client: Client, msg: NatsMsg<MsgInput>, meta: any) {
    // send email
    let emailTemplate = meta.template;
  }
}

Sub Services

// comments.service.ts
import { SUBJECT, NatsEvents } from '@pestras/micro-nats';
import { Client, Payload} from 'ts-nats';

export class Comments implements NatsEvents {

  onNatsConnected(client: Client) {
    // ...
  }
  
  validate(client: Client, msg: NatsMsg, handlerName: string) { return true }
  
  @SUBJECT('newComment', {
    // auth hook from the main service
    // validate hook from the local service (sub service)
    hooks: ['auth', 'validate']
  })
  create(client: Client, msg: NatsMsg) {
    
  }
}

// main.ts
import { Micro, SERVICE } from '@pestras/micro';
import { SUBJECT, NATS_HOOK } from '@pestras/micro-nats';
import { Client, Payload} from 'ts-nats';

Micro.plugins(new MicroNats());

@SERVICE()
class Articles {

  onInit() {    
    Micro.store.someSharedValue = "shared value";
  }
  
  async auth(client: Client, msg: NatsMsg, handlerName: string) {
    return true;
  }
  
  validate(client: Client, msg: NatsMsg, handlerName: string) {
    return true;
  }

  @SUBJECT('newArticle', {
    // both hooks from the main service
    hooks: ['auth', 'validate']
  })
  create(client: Client, msg: NatsMsg) {
    
  }
}

// pass sub services as an array to the second argument of Micro.start method
Micro.start(Articles, [Comments]);

Local hooks has the priority over main service hooks.
Subservices have their own lifecycle events.

lifecycle Events

onNatsConnected

Called whenever nats driver has a successfull connection

import { SERVICE, Micro } from '@pestras/micro';
import { SUBJECT, NatsMsg, NatsEvents } from '@pestras/micro-nats';
import { Client, Payload} from 'ts-nats';

Micro.plugins(new MicroNats());

interface MsgInput { id: string; email: string }

@SERVICE()
class Email implements NatsEvents {

  onNatsConnected(client: Client) {
    // ...
  }

  @SUBJECT('emails.new')
  sendActivataionEmail(client: Client, msg: NatsMsg<MsgInput>) {
    // send email
  }
}

Thank you