Kotlin on the Cloud

Slides for my 'Kotlin on the Cloud' talk at the Google Developer Group Lisboa's Kotlin Night.

Transcript

1. Kotlin on the
   Cloud
   João Carvalho - GDG Lisboa - Oct 12 2017
   

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2. About me
   

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3. About me
   ● Senior Developer / Team Lead @ Talkdesk
   ● Backend Developer
   ● IST Alumni (Student & Developer)
   ● PT.JUG Speaker
   ● Follow me on Twitter @johnkarva
   

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4. Cloud Native Apps
   https://pivotal.io/cloud-native
   

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5. “Cloud-native is an approach to building and
   running applications that fully exploits the
   advantages of the cloud computing delivery
   model. Cloud-native is about how
   applications are created and deployed, not
   where.”
   

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6. ● Devops
   ● Continuous Delivery
   ● Microservices
   ● Containerization
   

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7. Predictability
   

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8. 12 Factor App
   1. Single codebase, multiple deploys
   2. Explicit Dependencies
   3. Store Config in Environment
   4. Backing Services as resources
   5. Separate Build, Release, Execution
   6. Standalone (Volatile) Process
   7. Port Binding
   8. Multiple Process Types
   9. Disposability
   10. Environment Parity
   11. Logs as Event Streams
   12. One-off Admin Tasks
   

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9. OS-Agnostic
   

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10. Auto-Scaling
    

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11. Independence
    

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12. Quick Recovery
    

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13. Agility
    

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14. Kotlin
    

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15. Why not Java 8/9?
    

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16. Null Safety
    

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17. public void printName(Person person) {
    System.out.println(person.getName());
    }
    

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18. public void printName(Person person) {
    System.out.println(person.getName());
    }
    null
    

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20. fun printName(person: Person) {
    println(person.name)
    }
    

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21. printName(null)
    ERROR: Null cannot be a value of non-null
    type Person.
    

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22. fun printName(person: Person?) {
    if (person != null) {
    println(person.name)
    }
    }
    

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23. Safe Navigation
    

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24. private String safeGetName(Person person) {
    return person == null ? null :
    person.getName();
    }
    

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25. fun safeGetName(person: Person?): String? {
    return person?.name
    }
    

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26. fun safeGetName(person: Person?): String {
    return person?.name ?: "Unknown"
    }
    

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27. Properties
    

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28. class Person(name: String) {
    private val name: String
    init {
    this.name = name
    }
    }
    

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29. class Person(private val name: String)
    

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30. Delegated Properties
    

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31. val lazyValue: String by lazy {
    println("computed!")
    "Hello"
    }
    

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32. Extension Functions
    

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33. fun String.helloize() = "Hello $this"
    "World".helloize()
    

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34. Data Classes
    

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35. public class Person {
    private String name;
    private int age;
    public Person(String name, int age) {
    this.name = name;
    this.age = age;
    }
    (...)
    }
    

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36. public String getName() {
    return name;
    }
    public void setName(String name) {
    this.name = name;
    }
    @Override
    public boolean equals(Object o) {
    (Stuff generated by your IDE)
    }
    @Override
    public int hashCode() {
    int result = name.hashCode();
    result = 31 * result + age;
    return result;
    }
    

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38. data class Person(var name: String,
    var age: Int)
    

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39. data class Person(val name: String,
    val age: Int)
    

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40. val john = Person("John", 21)
    val olderJohn = john.copy(age = 78)
    

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41. And much more...
    ● No Semicolons!
    ● Lambda Expressions and Inline Functions
    ● Type inference
    ● Named Arguments
    ● Default Values
    ● String Interpolation
    ● Ranges
    ● Immutable Collections (Kind of)
    ● Collection helpers
    ● Infix Functions
    ● DSL Support
    

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42. Performance
    

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43. Tooling
    

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44. Getting Started
    

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49. @RestController
    @SpringBootApplication
    public class DemoApplication {
    public static void main(String[] args) {
    SpringApplication.run(DemoApplication.class, args);
    }
    @GetMapping("/hello")
    public String hello() {
    return "Hello World!";
    }
    }
    

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50. http://shop.oreilly.com/product/0636920038252.do
    

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51. Cloud-Native Kotlin?
    

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53. https://docs.spring.io/spring/docs/current/spring-framework-reference/kotlin.html
    

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54. Demo Time!
    

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55. Questions?
    

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