Kotlin EE: Boost your Productivity @ Voxxed Days Vienna 2018

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. @McPringle
   #VoxxedVienna
   Kotlin EE
   Boost Your Productivity
   Marcus Fihlon
   

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2. @McPringle
   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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3. Introduction
   

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4. @McPringle
   About me
   ● Software Engineer
   CSS Insurance, Open Source Software
   ● Agile Coach
   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,
   Voxxed Days Zürich, BaselOne
   

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5. @McPringle
   Coming soon*
   Kotlin Web Development
   Develop full stack web applications with Kotlin and React.js
   Packt Publishing
   ISBN 978-1-78862-031-4
   * around Q3/2018
   

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6. Why Kotlin
   

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7. @McPringle
   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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8. @McPringle
   Kotlin Syntax
   fun main(args: Array) {
   val event = "Voxxed Days Vienna"
   println("Hi $event!") // Hi Voxxed Days Vienna!
   }
   

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

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

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11. @McPringle
    Data classes
    data class Person(val name: String,
    val age: Int,
    val company: String?)
    val marcus = Person("Marcus", 44, null)
    println(marcus) // Person(name=Marcus, age=44, company=null)
    val marcusCSS = marcus.copy(company = "CSS Insurance")
    println(marcusCSS) // Person(name=Marcus, age=44, company=CSS Insurance)
    

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12. @McPringle
    Default Values
    data class Person(val name: String,
    val age: Int,
    val company: String? = null)
    val marcus = Person("Marcus", 44)
    println(marcus) // Person(name=Marcus, age=44, company=null)
    val marcusCSS = Person("Marcus", 44, "CSS Insurance")
    println(marcusCSS) // Person(name=Marcus, age=44, company=CSS Insurance)
    

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13. @McPringle
    Named Parameters
    data class Person(val name: String,
    val age: Int,
    val company: String? = null)
    val marcus = Person(name = "Marcus", age = 44)
    println(marcus) // Person(name=Marcus, age=44, company=null)
    val marcusCSS = marcus.copy(company = "CSS Insurance")
    println(marcusCSS) // Person(name=Marcus, age=44, company=CSS Insurance)
    

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14. @McPringle
    String Templates
    data class Person(val name: String,
    val age: Int,
    val company: String? = null)
    val marcus = Person(name = "Marcus", age = 44)
    println("$marcus.name is $marcus.age years old")
    // Marcus is 44 years old
    println("${marcus}.name is $marcus.age years old")
    // Person(name=Marcus, age=44, company=null).name is 44 years old
    

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15. @McPringle
    Multiline Strings
    data class Person(val name: String,
    val age: Int,
    val company: String? = null)
    val marcus = Person(name = "Marcus", age = 44)
    println("""Name: $marcus.name
    Age: $marcus.age
    Company: $marcus.company""")
    

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

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17. @McPringle
    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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18. @McPringle
    Typesafe Builder
    val page = html {
    head {
    title { "My Website" }
    }
    body {
    p { "Hello Voxxed Days Vienna!" }
    }
    }
    

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19. Why Java EE
    

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20. @McPringle
    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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21. @McPringle
    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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22. @McPringle
    It's a Standard!
    

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23. Kotlin EE
    

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

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26. Live Coding
    

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27. @McPringle
    Architecture
    

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28. @McPringle
    Prepare the Swarm
    ● List all available machines
    ● Create a new machine to be used as a manager node
    ● Create a new machine to be used as a worker node
    ● Login to the manager
    ● Initialize the swarm
    

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29. @McPringle
    ● Start the visualizer service
    ● Open the visualizer service in a web browser
    Prepare the Visualizer
    

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30. @McPringle
    Join the Swarm
    ● Ask the manager node for the token to join the swarm
    ● Login to the worker node
    ● Join the worker to the swarm
    

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31. @McPringle
    Verify the Swarm
    ● Login to the manager
    ● List all nodes
    ● Show more detailed information
    

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32. @McPringle
    Create a Network
    ● Login to the manager
    ● Create a new overlay network
    ● List all networks
    

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33. @McPringle
    Deploy Services
    ● Login to the manager
    ● Deploy the time service
    ● Deploy the hello service
    ● List all services
    

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34. @McPringle
    Testing, Scaling and Maintenance
    ● Testing our services
    ● Scaling services up and down
    ● Take a node out of service
    ● Take a node back into service
    

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35. Wrap-up
    

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36. @McPringle
    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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37. @McPringle
    You ever dreamed of living in Switzerland?
    

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38. @McPringle
    Code Warriors wanted!
    About you
    ● You are frighteningly awesome at what you do.
    ● You can perform quick and deadly tactical
    strikes, as well as feats of epic badassery.
    Sometimes both at the same time.
    ● You would rather refactor existing, mostly
    working, ugly code instead of rewriting it from
    scratch. OK nobody would really rather do that,
    but you know it's the right and honorable thing
    to do most of the time.
    ● You know where your towel is.
    About us
    ● Biggest Basic Health Insurance Company
    ● 2700 Employees
    ● 300 IT Professionals
    ● 24 Scrum Teams
    ● 130 Software Developers
    ● Flexible working times
    ● Personal development support
    ● 6 weeks paid vacation
    ● Great benefits
    ● Located in Lucerne, Switzerland
    Contact me: marcus.fihlon@css.ch
    

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39. @McPringle
    https://fihlon.ch/vdv18
    

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