Design Pattern

why they are still important in the microservice era

Once upon a time,

there were only monoliths

your application was written in a one repo

and the deployment was simple

We know how to structure the code

We know how to test the code

We know how to deploy our application

We know how to monitor our application

We know how to improve performance

We know how to add new feature

More than 20 years of knowledge

Erich Gamma

Richard Helm

Ralph Johnson

John Vlissides

Design Patterns

Factory

Builder

Singleton

Adapter

Facade

Proxy

Iterator

Observer

Strategy

Visitor

They helped us

TILL NOW

Know which domains are involved

What we need to build a microservice ecosystem

Choose which µs should scale up

Find the common needs to refactorize them

Consistent deployment system

Another way

We can use our knowledge

to reach the business

as soon as possible

without complicating the code too much

Build a monolith using the design patterns

to split it later

It is easier with the right tool

Fastify can be a solution

Decorators

Encapsulation

// Injection
fastify.decorate('myObject', new MyObject({ /* ... */ ))

fastify.decorate('myCounter', 0)

fastify.decorateRequest('getUserId', function () {
  return this.headers['mia-user']
})


// Usage
fastify.get('/', myHandler)

function myHandler (request, reply) {
  const userId = request.getUserId()
  const result = this.myObject.getResult()
  reply.send(result)
}
fastify.register(plugin1, { prefix: '/plugin1/' })

fastify.register(plugin2, { prefix: '/plugin2/' })

// Plugin1

function plugin1 (fastify, o, n) {
  fastify.decorate('myObject', new MyObject({ /* ... */ })

  fastify.get('/', myHandler)
}


// Plugin2

function plugin2 (fastify, o, n) {
  fastify.decorate('myObject', new MyObject({ /* ... */ })

  fastify.get('/', myHandler)
}

An example

twitter

User

UserService

UserClient

HTTP routes

Tweet

TweetService

TweetClient

HTTP routes

Follow

FollowService

FollowClient

HTTP routes

Timeline

TimelineService

HTTP routes

Fastify

So

start simple

complicate later

Thanks

Design pattern in microservice era

By Tommaso Allevi

Design pattern in microservice era

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