Microservices: Klein, aber oho!

Microservices:
Klein, aber oho!

Stephan Hochdörfer // 22.04.2015

Über mich

Stephan Hochdörfer
Head of Technology, bitExpert AG
Mannheim
S.Hochdoerfer@bitExpert.de
@shochdoerfer
#DevOps, #Automation, #unKonf

Der Fluch des Monolithen

Einschüchternde Codebasis

Fragiles System

Langfristige Verpflichtung

Versuch eines Rewrites?

Die Legacy Wahrheit

Legacy code is a business asset that helped the business get where it is. Treat it with respect.
— Yann Larrivée (@ylarrivee) 22. Dezember 2014

Die LTS Wahrheit

good long term software is not commonly about reuse, its about the ability to rewrite completely isolated bits without hitting the big bang
— gregyoung (@gregyoung) 2. September 2014

Die Lösung?

« [...] This is the Unix philosophy: Write
programs that do one thing and do it well. »
- Doug McIlroy

Zusammenarbeit

« [...] Write programs to work together. Write programs to
handle text streams, because that is a universal interface. »
- Doug McIlroy

Was sind Microservices?

« [...] approach to developing a single application as a suite of small services, each running in its own process and communicating with lightweight mechanisms. »
- James Lewis, Martin Fowler

"Nur" SOA? Oder besser?

I guess it is easier to use a new name (Microservices) rather than say that this is what SOA actually meant - re http://t.co/gvhxDfDWLG
— Arnon Rotem-Gal-Oz (@arnonrgo) 16. März 2014

Kleine Problemdomäne

Single Responsibility

« A class should have one, and
only one, reason to change. »
- Robert C. Martin

Isolierter Prozeß

Docker

Microservices Platform

Deployment Automatisierung

Build + Deployment isolieren

Separater Datenspeicher

Einfache Kommunikation

Smart endpoints, dumb pipes

« Be of the web, not behind the web. »
- Ian Robinson

Open/closed principle

« You should be able to extend a classes
behavior, without modifying it. »
- Robert C. Martin

Datenstruktur-Evolution

{
  "id": 123,
  "name": "My Product",
  "categories": [{
    "id": 12,
    "name": "My category"
  }],
  "price": 12.34
  "currency": "EUR"
}

{
  "id": 123,
  "name": "My Product",
  "categories": [{
    "id": 12,
    "name": "My category"
  }],
  "price": [12.34, 14.26]
  "currency": ["EUR", "USD"]
}

Datenstruktur-Evolution

{
  "id": 123,
  "name": "My Product",
  "categories": [{
    "id": 12,
    "name": "My category"
  }],
  "prices": [{
    "price": 12.34,
    "currency": "EUR"
  }, {
    "price": 14.26,
    "currency": "USD"    
  }]
}

Bauen, Deployen, Supporten

Warum Microservices?

« Microservices are organised around
business capabilities. » - Martin Fowler

Observe, Orient, Decide, Act

Team Organisation

Kleine, fokussierte Teams

Mehr Macht den Entwicklern!

Nutze das "passende" Tool...

...oder tausche es aus!

Liskov substitution principle

« Derived classes must be substitutable
for their base classes. » - Robert C. Martin

Skalierung wird einfacher!

Entwicklung wird schneller...

...je nach Bedarf!

A/B Testing für Services

Herausforderungen

« There ain’t no such thing as a free lunch. »
- Robert A. Heinlein

Nicht so einfach!

"If you can't build a structured monolith, what makes you think micro-services is the answer" -- Simon Brown
— 酱油海盗 (@phaytsukiming) March 6, 2015

Kleine Services FTW!

Small teams typically work better than big teams. Small services typically work better than monoliths. #microservices #microservice
— Jason Chambers (@microsvcs) 1. April 2014

Was heißt denn "klein"?

@olivergierke Microservices are neither micro nor service. :-)
— Eberhard Wolff (@ewolff) 31. Oktober 2014

Interface Segregation

« Make fine grained interfaces that
are client specific. » - Robert C. Martin

Standardisierung notwendig!

Monitoring und Logging

Keine verteilte Transaktionen!

Keine kaskadierende Fehler!

Design for failure

@olivergierke No. I meant to says that REST is not the most difficult problem for Microservices. E.g. resilience is probably harder.
— Eberhard Wolff (@ewolff) March 2, 2015

Früh und oft releasen!

Automatisierung FTW!

Dependency Inversion

« Depend on abstractions, not on concretions. »
- Robert C. Martin

Service Discovery

Service Discovery Beispiel

<dependencies>
    <dependency>
        <groupId>com.orbitz.consul</groupId>
        <artifactId>consul-client</artifactId>
        <version>0.8.2</version>
    </dependency>
</dependencies>

Consul consul = Consul.newClient();
HealthClient healthClient = consul.healthClient();

List<ServiceHealth> nodes = healthClient.getHealthyNodes("DataService").getResponse();

Dokumentation FTW!

jhipster

jhipster Beispiel

$ npm install -g generator-jhipster

$ yo jhipster

$ mvn spring-boot:run

$ yo jhipster:cloudfoundry

Spring Boot

Spring Boot Beispiel

@Controller
class MyApp {
    @RequestMapping("/")
    @ResponseBody
    String home() {
        "Hello World!"
    }
}

$ spring run app.groovy

Vielen Dank! Fragen?