Reloading Java Applications Like A Pro

Transcript

1. reloading java applications
   like a pro
   Anton  Arhipov  
   

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2. whoami
   anton arhipov
   @antonarhipov
   jrebel product lead
   zeroturnaround
   

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3. agenda
   • the time sink
   • application updates (with jrebel)
   

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4. make a
   change
   build,
   deploy,
   wait
   check the
   change
   the turnaround
   

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5. package everything into WAR/EAR
   rackage modules into JARs
   compile classes
   copy static resources
   resolve dependencies
   build
   

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6. exploded directory deployment
   

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7. public class Launcher {
   public static void main(String[] args) {
   Server server = new Server();
   SelectChannelConnector connector
   = new SelectChannelConnector();
   connector.setPort(8080);
   server.addConnector(connector);
   WebAppContext context = new WebAppContext("war", "/");
   server.setHandler(context);
   server.start();
   }
   }
   jetty launcher
   

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8. “…I  know  about  JRebel,  but  I  cannot  
   pay  for  it,  so  I  tried  Maven…”  
                                                                                        -­‐  Stackoverflow  
   

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9. getResource(“hello.html”)   read(“src/main/.../hello.html”)  
   

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10. package everything into WAR/EAR
    rackage modules into JARs
    compile classes
    copy static resources
    resolve dependencies
    build
    

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11. package everything into WAR/EAR
    rackage modules into JARs
    compile classes
    copy static resources
    resolve dependencies
    build
    

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12. no build!
    • compile with your IDE
    • prefer exploded deployment
    • avoid <>
    

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13. 1–60s 30s$–$15min ~1min
    container boot time
    application deployment
    navigation
    redeploy’s time
    

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14. h@p://dow.ngra.de/2010/12/14/jee-­‐oss-­‐container-­‐startup-­‐Jmes-­‐apples-­‐vs-­‐oranges/  
    container startup time
    

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15. h@p://zeroturnaround.com/java-­‐ee-­‐producJvity-­‐report-­‐2011/  
    

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16. Externalized   Temporary  
    Serializable   DerivaJve  
    State  
    why code reloading is hard?
    

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17. MyObject  
    MyObject.class  
    OldClassLoader   NewClassLoader  
    MyObject.class  
    MyObject  
    Recreate  object  
    naiive class reloading
    

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18. Classes
    Libraries
    OldClassLoader NewClassLoader
    Sevlet New
    Classes
    New
    Libraries
    Sevlet
    Session Session
    init()  
    App
    State
    App
    State
    serialize/deserialize
    

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19. Classes
    OldClassLoader NewClassLoader
    Sevlet New
    Classes
    New
    Libraries
    Sevlet
    Session Session
    App
    State
    App
    State
    

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20. MyObject
    MyObject.class  
    OldClassLoader
    Code  
    101000101  
    100010010  
    Debugger
    HotSwap  
    New  code  
    111000100  
    101010010  
    New  code  
    111000100  
    101010010  
    hotswap
    Make  changes  
    

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21. MyObject
    MyObject.class  
    OldClassLoader
    Code  
    101000101  
    100010010   New  code  
    111000100  
    101010010  
    JRebel  
    Framework  
    ConfiguraJon  
    (XML,  annotaJons,..)  
    jrebel
    Make  changes  
    

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22. HotSwap   JRebel  
    Changing  method  bodies   +   +  
    Adding/removing  methods   -­‐   +  
    Adding/removing  constructors   -­‐   +  
    Adding/removing  fields   -­‐   +  
    Adding/removing  classes   -­‐   +  
    Adding/removing  annotaJons   -­‐   +  
    Replacing  superclass   -­‐   -­‐  
    Adding/removing  implemented  
    interfaces  
    -­‐   -­‐  
    jrebel vs hotswap
    

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23. in action
    

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24. Java
    App
    Framework
    Conf
    XML
    HTTP request
    

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25. Java
    App
    Framework
    Conf
    XML
    HTTP request
    1) Stop request
    

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26. Java
    App
    Framework
    Conf
    XML
    HTTP request
    2) Check resources
    

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27. Java
    App
    Framework
    Conf
    XML
    HTTP request
    3) Reconfigure
    the framework
    

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28. Java
    App
    Framework
    Conf
    XML
    HTTP request
    4) Resume request
    

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29. Java
    App
    Framework
    Conf
    XML
    HTTP request
    PROFIT! J
    

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30. Java
    App
    Framework
    Conf
    XML
    HTTP request
    OpJonally:  
    File  system    
    PUSH  
    

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32. application reloading is hard
    • requires more than just class
    reloading
    • reloading of different components
    should appear in particular order
    • bootstrapping
    

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33. with java ee
    

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34. jrebel for java ee
    • JSP
    • JAX-RS
    • JAX-WS
    • JSF
    • CDI
    • JPA
    • EJB
    • Jasper
    • Jersey, CXF
    • Metro
    • Mojarra, MyFaces
    • Weld
    • EclipseLink, OpenJPA, Hibernate
    

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35. goes cloud
    

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36. Remote Deployments
    • Development servers
    • Virtualized environments
    • Cloud environments
    

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37. Remote Deployments
    0. make a change
    1. git commit; git push
    2. mvn clean install
    3. deploy.sh
    

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38. 0. make a change
    1. compile
    2. synch & reload
    

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39. h@p://bit.ly/33degree2013    
    win a free license
    

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40. Questions?
    @antonarhipov
    anton@zeroturnaround.com
    

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