Kotlin EE: Boost your Productivity @ JavaOne17

Kotlin is a language for the JVM, invented by JetBrains a few years ago. But what the hell is Kotlin EE? If you never heard of Kotlin EE, don’t panic, it does not exist. But you can use it right away and boost your productivity!

I invented the term Kotlin EE as a synonym for using the Kotlin language together with the Java EE API to create services of any size (microservices, nanoservices etc.) with just a few lines of code and the ability to focus on the business logic.

Kotlin and Java EE are a perfect couple for writing micro- or nanoservices. Kotlin is a very pragmatic language, builds on many concepts and techniques from Java, designed for developer productivity. Kotlin works great with all existing Java libraries and frameworks and runs with the same level of performance as Java.

The Java EE API allows us to code against a proven and stable API. Provided libraries like JAX-RS for writing RESTful APIs and Jackson for JSON (de)serializing decrease the need for additional third-party libraries which results in a short build time and a small artifact size. Benefit from a very fast build and test feedback and stay focused on your code.

In this talk, I try to prove my statements from above. Live on stage I write a service in Kotlin with a RESTful JSON API with only a few lines of code and run the service using a local Docker cloud where you can see how these can be scaled up and down to manage fluctuating loads. Coding, building, testing, deploying, scaling: fast and efficient!

Transcript

1. Kotlin EE
   Boost Your Productivity
   Marcus Fihlon
   @McPringle
   October 1-5, 2017
   San Francisco
   

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2. Agenda
   ● Introduction
   ● Why Kotlin
   ● Why Java EE
   ● Kotlin EE
   ● Live Coding
   ● Wrap-Up
   

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3. Introduction
   

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4. Disclaimer
   The following presentation has been approved for open audiences only. Hypersensitivity to occasional
   profanity requires covering ears.
   All logos, photos etc. used in this presentation are the property of their respective copyright owners and
   are used here for educational purposes only. Any and all marks used throughout this presentation are
   trademarks of their respective owners.
   The presenter is not acting on behalf of CSS Insurance, neither as an official agent nor representative. The
   views expressed are those solely of the presenter.
   Marcus Fihlon disclaims all responsibility for any loss or damage which any person may suffer from reliance
   on this information or any opinion, conclusion or recommendation in this presentation whether the loss or
   damage is caused by any fault or negligence on the part of presenter or otherwise.
   

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5. About me
   ● Software Engineer
   CSS Insurance, Open Source Software
   ● Scrum Master
   CSS Insurance
   ● Lecturer
   TEKO Swiss Technical College
   ● Speaker
   Conferences, User Groups, Meetups
   ● Author
   Articles, Books
   ● Community Leader
   Hackergarten, Java User Group Switzerland, Kotlin Swiss User Group
   

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6. Coming soon*
   Kotlin Web Development
   Develop full stack web applications with Kotlin and React.js
   Packt Publishing
   ISBN 978-1-78862-031-4
   * around Q2/2018
   

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7. Buzzword Bingo
   ● Monolith
   Bad by default!
   ● Microservices
   Solve every problem!
   ● Nanoservices
   Solve all other Problems!
   ● Docker
   Just because it's cool!
   ● Java EE
   Uncool and heavy framework for bloated monoliths!
   

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8. Why Kotlin
   

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9. About Kotlin
   ● Statically typed
   ● Object oriented
   ● Java compatible
   ● Easy to learn
   ● Compiles to Java 6 Bytecode
   ● Compiles to Java 8 Bytecode
   ● Transpiles to JavaScript
   ● Compiles to Native
   

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10. Kotlin Syntax
    fun main(args: Array) {
    val event = "JavaOne"
    println("Hi $event!")
    }
    

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11. Classes and Properties
    class Person(val name: String,
    val age: Int,
    val company: String?) {
    …
    }
    

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12. Classes final by default
    open class Person(val name: String,
    val age: Int,
    val company: String?) {
    …
    }
    

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13. Data classes
    data class Person(val name: String,
    val age: Int,
    val company: String?)
    val marcus = Person("Marcus", 29, null)
    println(marcus) // Person(name=Marcus, age=43, company=null)
    val marcusCSS = marcus.copy(company = "CSS Insurance")
    println(marcusCSS) // Person(name=Marcus, age=43, company=CSS Insurance)
    

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14. Singletons
    object PersonController {
    val persons = mutableListOf()
    fun save(person: Person) {
    persons.add(person)
    }
    …
    }
    

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15. Coroutines
    fun main(args: Array): Unit = runBlocking {
    val jobs = List(10) {
    async(CommonPool) {
    PriceService().price
    }
    }
    println(jobs.sumBy { it.await() } / 10)
    }
    

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16. Typesafe Builder
    val page = html {
    head {
    title { "My Website" }
    }
    body {
    p { "Hello JavaOne!" }
    }
    }
    

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17. Why Java EE
    

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18. Library Management as a Service
    ● Servlets, JSTL, EL and JSPs
    ● WebSockets
    ● JSF
    ● JAX-RS
    ● EJB lite
    ● JTA
    ● JPA
    ● Bean Validation
    ● CDI
    ● Interceptors
    ● JBatch
    ● Concurrency
    ● JCache
    ● …
    dependencies {
    providedCompile "javax:javaee-api:$javaee_version"
    }
    

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19. Ready to use containers
    FROM payara/micro
    COPY myapplication.war /opt/payara/deployments
    My Application
    Application Server
    Java Runtime
    Operating System changes very infrequently
    changes sometimes, if not delayed
    changes frequently
    changes on every build
    

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20. It's a Standard!
    

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21. Kotlin EE
    

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22. Classes final by default
    buildscript {
    dependencies {
    classpath "org.jetbrains.kotlin:kotlin-allopen:$kotlin_version"
    }
    }
    allOpen {
    annotation('javax.ejb.Stateless')
    annotation('javax.ws.rs.Path')
    }
    

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23. Zero-Argument Constructor
    buildscript {
    dependencies {
    classpath "org.jetbrains.kotlin:kotlin-noarg:$kotlin_version"
    }
    }
    noArg {
    annotation('javax.ws.rs.Path')
    }
    

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24. Live Coding
    

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25. Architecture
    

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26. Prepare the Swarm
    ● List all available machines
    docker-machine ls
    ● Create a new machine to be used as a manager node
    docker-machine create -d virtualbox mgr
    ● Create a new machine to be used as a worker node
    docker-machine create -d virtualbox node01
    ● Login to the manager
    docker-machine ssh mgr
    ● Initialize the swarm
    docker swarm init --advertise-addr 192.168.99.100
    

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27. Prepare the Visualizer
    ● Start the visualizer service
    docker run -it -d -p 8080:8080 -e HOST=192.168.99.100 \
    -v /var/run/docker.sock:/var/run/docker.sock \
    --name visualizer dockersamples/visualizer
    ● Open the visualizer service in a web browser
    http://192.168.99.100:8080/
    

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28. Join the Swarm
    ● Ask the manager node for the token to join the swarm
    docker swarm join-token worker
    ● Login to the worker node
    docker-machine ssh node01
    ● Join the worker to the swarm
    docker swarm join --token 192.168.99.100:2377
    

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29. Verify the Swarm
    ● Login to the manager
    docker-machine ssh mgr
    ● List all nodes
    docker node ls
    ● Show more detailed information
    docker info
    

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30. Create a Network
    ● Login to the manager
    docker-machine ssh mgr
    ● Create a new overlay network
    docker network create -d overlay javaone
    ● List all networks
    docker network ls
    

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31. Deploy Services
    ● Login to the manager
    docker-machine ssh mgr
    ● Deploy the time service
    docker service create --network javaone \
    --name timeservice mcpringle/timeservice
    ● Deploy the hello service
    docker service create --network javaone -p 8181:8080 \
    --name helloservice mcpringle/helloservice
    ● List all services
    docker service ls
    

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32. Testing, Scaling and Maintenance
    ● Testing our services
    curl http://192.168.99.100:8181/api/hello/javaone
    ● Scaling services up and down
    docker service update --replicas 3 helloservice
    ● Take a node out of service
    docker node update --availability drain mgr
    ● Take a note back into service
    docker node update --availability active mgr
    

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33. Wrap-up
    

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34. Conclusion
    With Kotlin, Java EE and Docker you get:
    ● Easy to understand code
    ● Fast build times
    ● Reproducible deployments
    ● Easy scaling of your services
    You are fast and efficient because you have your focus on your business code.
    You create business value!
    

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35. @McPringle
    

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