How to use a JVM library in node.js

Transcript

1. Laurynas Lubys, backend developer @ Wix
   How to use a JVM library
   in node.js
   laurynasl@wix.com linkedin.com/in/laurynaslubys github.com/laurynasl-wix
   

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2. AGENDA
   Interop 101
   Sync interop
   Async interop
   

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3. How to use a JVM library
   in node.js
   

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4. The docs
   ▪ https://github.com/graalvm/graaljs/blob/master/docs/user/JavaInterop.md
   ▪ https://www.graalvm.org/docs/reference-manual/languages/js/
   INTEROP 101
   

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5. INTEROP 101
   Graal
   JVM Compiler Interface
   JVM Runtime
   Truffle
   Drop in replacement for
   node.js (mostly compatible
   with existing libs)
   TLDR;
   

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6. JVM interop enabled with
   --jvm
   INTEROP 101
   Graal
   JVM Compiler Interface
   JVM Runtime
   Truffle
   Drop in replacement for
   node.js (mostly compatible
   with existing libs)
   TLDR;
   

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7. TLDR;
   INTEROP 101
   Graal
   JVM Compiler Interface
   JVM Runtime
   Truffle
   Most cross language calls do
   not need conversions at
   runtime
   JVM interop enabled with
   --jvm
   Drop in replacement for
   node.js (mostly compatible
   with existing libs)
   

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8. hello-world.js
   const System =
   Java.type("java.lang.System");
   System.out.println("Hello world!");
   INTEROP 101
   Java
   Graal
   global scope
   JVM
   

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9. hello-world.js
   node --jvm hello-world.js
   > Hello world!
   const System =
   Java.type("java.lang.System");
   System.out.println("Hello world!");
   INTEROP 101
   run it!
   Java
   Graal
   global scope
   JVM
   

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10. How to use a JVM library
    in node.js
    Use case #1
    Sync
    interop
    

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11. SYNC
    INTEROP
    Use case #1
    bcrypt
    A CPU intensive hashing function
    

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12. Use case #1
    The Goal
    bcrypt
    SYNC
    INTEROP
    ▪ Use the JVM bcrypt library in node.js
    ▪ Integrate it into our server to handle user logins
    

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13. bcrypt
    SYNC
    INTEROP
    The Plan
    1. Tell the JVM where to find the jar
    2. Call it from node
    3. Use it in our application
    4. Go home early
    

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14. SYNC
    INTEROP
    1. Tell the JVM where to find the jar
    2. Call it from node
    3. Use it in our application
    4. Go home early
    --vm.cp Java.addToClasspath(path)
    OR
    

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15. SYNC
    INTEROP
    1. Tell the JVM where to find the jar
    2. Call it from node
    3. Use it in our application
    4. Go home early
    --vm.cp Java.addToClasspath(path)
    OR
    We’ll specify the classpath
    manually with --vm.cp
    

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16. SYNC
    INTEROP
    1. Tell the JVM where to find the jar
    2. Call it from node
    3. Use it in our application
    4. Go home early
    const BCrypt =
    Java.type("org.mindrot.jbcrypt.BCrypt");
    const salt =
    "$2a$10$sfMWTWROyUu5JxTEwm413u";
    const hash = BCrypt.hashpw("Hello", salt);
    console.log(hash);
    bcrypt.js
    

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17. SYNC
    INTEROP
    1. Tell the JVM where to find the jar
    2. Call it from node
    3. Use it in our application
    4. Go home early
    const BCrypt =
    Java.type("org.mindrot.jbcrypt.BCrypt");
    const salt =
    "$2a$10$sfMWTWROyUu5JxTEwm413u";
    const hash = BCrypt.hashpw("Hello", salt);
    console.log(hash);
    bcrypt.js
    FLAGS="\
    --jvm \
    --vm.cp=./jbcrypt-0.3m.jar"
    node $FLAGS bcrypt.js
    > $2a$1...ugoQ3u/Mjb/CYi
    run it!
    

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18. SYNC
    INTEROP
    1. Tell the JVM where to find the jar
    2. Call it from node
    3. Use it in our application
    4. Go home early
    const BCrypt =
    Java.type("org.mindrot.jbcrypt.BCrypt");
    const salt =
    "$2a$10$sfMWTWROyUu5JxTEwm413u";
    app.post('/login', (req, res) => {
    const pass = req.query.password;
    res.send(BCrypt.hashpw(pass, salt));
    });
    app.js
    

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19. Demo time!
    SYNC
    INTEROP
    

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20. Cool, ship it!
    SYNC
    INTEROP
    

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21. 1. Tell the JVM where to find the jar
    2. Call it from node
    3. Use it in our application
    4. Go home early
    We blocked the event loop
    SYNC
    INTEROP
    

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22. 1. Tell the JVM where to find the jar
    2. Call it from node
    3. Use it in our application
    4. Go home early
    We blocked the event loop
    fortunately...
    The node community
    knows how to deal with
    blocking workloads
    SYNC
    INTEROP
    

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23. 1. Tell the JVM where to find the jar
    2. Call it from node
    3. Use it in our application
    4. Go home early
    We blocked the event loop
    fortunately...
    The node community
    knows how to deal with
    blocking workloads
    so
    We can create a pool of workers
    and do the work there
    SYNC
    INTEROP
    

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24. How to use a JVM library
    in node.js
    Not so trivial,
    but it works
    Use case #2
    Sync
    interop
    Async
    interop
    

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25. Use case #2
    ASYNC
    INTEROP
    rabbitmq
    The Goal
    ▪ Consume messages from rabbitmq
    ▪ We want to use the rabbitmq “push API”
    

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26. ASYNC
    INTEROP
    rabbitmq
    The Plan
    1. Figure out how to do callbacks with Graal
    2. Define the Java API
    3. Handle a rabbitmq message in node
    

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27. ASYNC
    INTEROP
    callback.js
    1. Figure out how to do callbacks with Graal
    3. Handle a rabbitmq message in node
    2. Define the Java API
    const Arrays = Java.type("java.util.Arrays");
    const javaList = Arrays.asList(1, 2);
    javaList.stream()
    .map(v => `In node: ${v}`)
    .forEach(console.log);
    

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28. const Arrays = Java.type("java.util.Arrays");
    const javaList = Arrays.asList(1, 2);
    javaList.stream()
    .map(v => `In node: ${v}`)
    .forEach(console.log);
    callback.js
    run it!
    ASYNC
    INTEROP
    node --jvm callback.js
    > In node: 1
    > In node: 2
    1. Figure out how to do callbacks with Graal
    2. Define the Java API
    3. Handle a rabbitmq message in node
    

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29. ASYNC
    INTEROP
    interface MessageQueue {
    void init();
    void addConsumer(
    String queueName,
    Handler handler
    );
    interface Handler {
    void handle(String message);
    }
    }
    1. Figure out how to do callbacks with Graal
    2. Define the Java API
    3. Handle a rabbitmq message in node
    

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30. ASYNC
    INTEROP
    const RabbitMQ = Java.type("mq.RabbitMQ");
    const mq = new RabbitMQ();
    mq.init();
    const handle = console.log;
    mq.addConsumer("hello-rabbit", handle);
    1. Figure out how to do callbacks with Graal
    2. Define the Java API
    3. Handle a rabbitmq message in node
    

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31. Demo time!
    ASYNC
    INTEROP
    

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32. We can’t call JS from another thread
    Java
    function
    ASYNC
    INTEROP
    

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33. bindCallback
    Java
    function
    ASYNC
    INTEROP
    

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34. GraalJS does not provide that
    out of the box
    ASYNC
    INTEROP
    

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35. Let’s see what we can do about that
    GraalJS does not provide that
    out of the box
    ASYNC
    INTEROP
    

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36. InteropBus
    Async Java code
    pending
    complete( )
    ( , )
    We want to call with async results from java.
    node.js
    worker
    node.js
    Java land
    bindCallback
    on(‘message’)
    

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37. 4. implement handlers that can be called from a different thread
    ASYNC
    INTEROP
    1. Figure out how to do callbacks with Graal
    2. Define the Java API
    3. Handle a rabbitmq message in node
    

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38. class JSHandler implements MessageQueue.Handler {
    BoundJSCallback jsCallback;
    JSHandler(BoundJSCallback jsCallback) {
    this.jsCallback = jsCallback;
    }
    @Override
    void handle(String message) {
    jsCallback.apply(new Object[]{message});
    }
    }
    JSHandler.java
    ASYNC
    INTEROP
    

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39. const RabbitMQ = Java.type("mq.RabbitMQ");
    const mq = new RabbitMQ();
    mq.init();
    const JSHandler = Java.type("mq.JSHandler");
    const {bindCallback} = require("../../interop");
    const handle =
    new JSHandler(bindCallback(console.log));
    mq.addConsumer("hello-rabbit", handle);
    Take #2
    ASYNC
    INTEROP
    

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40. Demo time!
    ASYNC
    INTEROP
    

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41. Not so trivial,
    but it works
    Works, not straightforward,
    mostly infrastructure
    Sync
    interop
    Async
    interop
    

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42. Questions?
    laurynasl@wix.com linkedin.com/in/laurynaslubys github.com/laurynasl-wix
    github.com/laurynasl-wix/graal-jvm-interop-talk
    

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43. Thank You
    laurynasl@wix.com linkedin.com/in/laurynaslubys github.com/laurynasl-wix
    github.com/laurynasl-wix/graal-jvm-interop-talk
    

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