node-reef-service

A nodejs service for the Reef arquitectural pattern

#How to Reef uses Amazon SQS queues, so you need an AWS account and the credentials to use it.

Set up

import { SqsBrokerFacade, ReefService } from 'reef-service';
import bunyan from 'bunyan';

let log = bunyan.createLogger({
  name        : 'foo',
  level       : process.env.LOG_LEVEL || 'info',
  stream      : process.stdout,
  serializers : bunyan.stdSerializers
});

let brokerFacade = new SqsBrokerFacade({
    region: process.env.AWS_REGION,
    accessKeyId: process.env.AWS_ACCESSKEYID,
    secretAccessKey: process.env.AWS_SECRETACCESSKEY,
    clientDomain: "serviceDomain",
    clientLane: "singleton"
});

let service = new ReefService(brokerFacade);

log.info('Setting up runners'); //The ones that listen for commands and fireAndForgets

service.addRunner("SAVE_USER", saveUser); //service.addRunner(commandToListen, function)

log.info('Setting up resolvers'); //The ones that listen for queries

service.addResolver("GET_USER_INFORMATION", userInformation);

log.info('Setting up Reef Service');
await service.setup();

log.info('Starting up Reef Service');
await service.start();

log.info('Adding info listener');
service.on('info', (info) => {
    log.info('Reef layer info: ', info);
});

log.info('Adding warn listener');
service.on('warn', (info) => {
    log.warn('Reef layer info: ', info);
});

log.info('Adding error listener');
service.on('error', (error) => {
    log.error('Reef layer info: ', error);
});

log.info('Listening');

Programming functions

There are two types of functions that reef accepts: runners and resolvers.

import mysql from 'mysql';
import databaseConnection from './databaseConnection'; //For more detail in how to implement a mysql connection visit mysql repository

async function saveUser(parameters){ //parameters is the payload that the client sends
  
 let query = `INSERT INTO subscriptor
            (user, name, lastName)
            VALUES (?, ?, ?)`;
    
  let inserts = [parameters.user, parameres.name, parameters.lastName];
  query = mysql.format(query, inserts);

  return new Promise( (resolve, reject) => {
        databaseConnection.query(query, (err, rows, fields) => {
            if (err){
                bunyanLog.info(err);
                resolve({
                  success: false,
                  error: err
                });
            }
            
            resolve({
              success: true
            });

        });
    });
}

The object that the client will receive is the one that is returned after the promise is resolved.

If a resolver/runner throws an error(reject), it will send a failuere message the the client, and the message will be deleted from the queue.

If a runner throws an error and the command type is a fireAndForget, the message will be requeued, and no response will be sent.

#How does it work

Each service has a request queue compose of the domain and lane. For example a queue full name will be:

serviceDomain-singleton-req

Each client has a response queue compose of the domain and lane. For example the queue name of the last example will be:

clientDomain-singleton-res

The service in the other side will send a message through that queue, and the cliente will process that.