Microservices with SenecaJS (part 2)

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Security Classification: Internal
MICROSERVICES WITH SENECAJS
Trung Dang Session 2

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Security Classification: InternalSecurity Classification: Internal
Agenda – Session 2
▪ Docker
▪ AMQP / RabbitMQ: What is it?
▪ SenecaJS transportation with AMQP
▪ Multiple service instances: PM2 or Docker?
▪ Consul - Service health checker & Configuration
▪ JWT for Auth
▪ Introducing servicebase package
▪ Q/A

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Sample source code is available at
https://github.com/immanuel192/seneca-with-rabbitmq-seminar

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Review Session 1

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Monolithic Application Model
1. How to scale this application to
serve more customer requests?
2. The Payments Module is taking
very long time to process the
requests. Is there any solution
with cheap cost?

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Microservices with Seneca, RabbitMQ, Consul, and FeathersJS
servicebase
Database Models
Service Logic
Service B
NGINX–LoadBalancer
GatewayAPI1GatewayAPI2
RabbitMQ
Configuration Storage & Health Checker
Docker
servicebase
Database Models
Service Logic
Service A
Redis

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Docker - https://www.docker.com/

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AMQP & RabbitMQ. What is it?
• RabbitMQ is a messaging broker - an intermediary for messaging.

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Service 1
RabbitMQ - How it works
Service 2
Queue
Queue
Exchange
client
Service 1

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docker run -d
--hostname rabbitmq-server
-p 5672:5672 -p 15672:15672
--name rabbitmq-server
-e RABBITMQ_DEFAULT_USER=username -e
RABBITMQ_DEFAULT_PASS=password
rabbitmq:management
Docker – Start RabbitMQ

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SenecaJS Philosophy
• Pattern Matching: instead of fragile service discovery, you just let
the world know what sort of messages you are about.
• Transport Independence: you can send messages between
services in many ways, all hidden from your business logic.

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SenecaJS – Your first microservice
let seneca = require('seneca')()
seneca.add('service:math,cmd:sum', (msg, reply) => {
reply(null, { answer: (msg.left + msg.right) })
})
seneca.act({ service: 'math', cmd: 'sum', left: 1, right: 2 },
(err, result) => {
if (err) return console.error(err)
console.log(result)
}
)

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SenecaJS – Pattern Matching
})
Can this service return the result as an integer only
whenever I need?

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SenecaJS – Pattern Matching - 2
seneca.add(‘service:math,cmd:sum’, function (msg,
reply) {
if (msg.integer === true){
reply(null, { answer: (parseInt(msg.left) +
parseInt(msg.right)) })
}
else{
}
})

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SenecaJS – Pattern Matching - 3
})
seneca.add('service:math,cmd:sum,integer:true', (msg, reply) =>
{
reply(null, {
answer: ( parseInt(msg.left) +
parseInt(msg.right)
)
})
})

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SenecaJS – Pattern Matching - Recap
• Matches against top level properties of JSON message
• Patterns are unique
• Specialised patterns win over generic patterns
• Competing patterns win based on value

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SenecaJS – Transport
• Seneca can work with multiple transports
• Available transports: RabbitMQ, Kafka, Redis, BeansTalk, mqp,
Mesh, SQS, NSQ, ZeroMQ, NATS, Azure Service Bus, NServiceBus,
Aliyun-MNS, Google Cloud PubSub
• HTTP/TCP is supported by default

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SenecaJS with AMQP Transport
• seneca-amqp-transport
https://github.com/seneca-contrib/seneca-amqp-transport
• It is a plugin to allow seneca listeners and clients to communicate
over AMQP
• Currently support AMQP 0.9.1
• For AMQP 1.0, please use seneca-servicebus-transport

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SenecaJS with AMQP Transport – Server
let seneca = require('seneca')()
.use('seneca-amqp-transport')
.add('service:myService,cmd:create', function (args, done) {
console.log(`From client ${args.clientId}: ${args.i}`);
done(null, { i: args.i })
})
.listen({
type: 'amqp',
pin: 'service:myService',
url: 'amqp://username:password@rabbitmq-server:5672'
})

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SenecaJS with AMQP Transport – Client
let clientId = 1
let args = process.argv.slice(2)
if (args.length > 0) {
clientId = args[0]
}
let client = require('seneca')().use('seneca-amqp-transport').client({
type: 'amqp',
pin: 'service:myService',
url: 'amqp://username:password@rabbitmq-server:5672'
})
let i = 0
setInterval(function() {
client.act(`service:myService,cmd:create,clientId:${clientId},i:${i}`,
function(err, ret) {
console.log('Client: received i = ' + ret.i);
});
i++;
}, 100)

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SenecaJS with AMQP Transport – How it works
Consumer Queue
Queue
myServiceclient
Request
reply_to = my_client_id
correlation_id = abc
Reply
correlation_id = abc
Queue
Client Queue
Routing
pin = service:myService
Routing
pin = my_client_id

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DEMO

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TEA-BREAK

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PM2
• Advanced process manager for production Node.js applications.
Load balancer, logs facility, startup script, micro service
management, at a glance.
• We can use pm2 to start our services with scale
pm2 start config-file.json
pm2 start your-app.js
pm2 scale app-name instance-number

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PM2 - Sample JSON configuration
File start-service.json
{
apps: [
{
name: "myService",
script: "index.js",
watch: false,
env: {
"NODE_ENV": "development"
},
instances: 1
}
]
}

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Docker – Run your service in multiple container
export pwd=`pwd`
docker run -d --link=rabbitmq-server -v "$pwd":/app
mhart/alpine-node:latest node /app/server.js
mhart/alpine-node:latest node /app/client.js 1
mhart/alpine-node:latest node /app/client.js 2

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Configuring your service
• How can we protect our configuration for production ENV?
• How can we monitor our services’s heath?
References:
• Health - Consul
https://www.consul.io/docs/agent/http/health.html
• Key / Value store - Consul
https://www.consul.io/docs/agent/http/kv.html

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JWT for Authentication
• JWT stands for Json Web Token
• No more cookies.
• JWT has 3 parts: header.body.signature
Example:
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJzY290Y2guaW8iLCJleHAiOjEzMDA4MTkzODAsIm5hbWU
iOiJDaHJpcyBTZXZpbGxlamEiLCJhZG1pbiI6dHJ1ZX0.03f329983b86f7d9a9f5fef85305880101d5e302afafa20
154d094b229f75
• JWT helps to verify the sender, authorize the request, prevent man
in middle and good with CORS.

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Introducing servicebase package
https://www.npmjs.com/package/servicebase
Features :
• Listener / Client mode, with AMQP Transport or HTTP Transport
• Promisify all functions
• Use Consul as Configuration Storage & Service Health Checker
• Support multiple database adapters. Postgresql & Sqlite are build-in supported adapters
• Use Loggly as logs monitoring service
• Support Authorization when consuming the service’s action
• Error handler: no more terminating your service because of TIMEOUT or fatal$ error
• Including test helper
• Including typed-definitions file

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DEMO

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Testing your services
• Use sqlite in-memory for integration test
• For unit-test: test your logic-class instead of test the function you
registered with seneca
• For integration-test with other services: use pm2 & rabbitmq

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Microservices are the kind of SOA. Microservices must be
independently deployable, whereas SOA services are often
implemented in deployment monoliths. Classic SOA is more platform
driven, so microservices offer more choices in all dimensions.
Torsten Winterberg (Oracle ACE Director)
Microservices vs SOA

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Q&A
Thank you very much

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Stateful / Stateless & Authorization
• Stateful means that there is memory of the past. Previous
transactions are remembered and may affect the current
transaction.
• Stateless means there is no memory of the past. Every transaction
is performed as if it were being done for the very first time.
• In Stateless service, we use JWT (Json Web Token) for
Authentication. No more Cookies.
• Authorization will be done by each service regarding to the
authenticated user.

Microservices with SenecaJS (part 2)

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Microservices with SenecaJS (part 2)