OSGI IS A SHINY THINGSHINY THINGS HAVE SHARP EDGES

SHARP EDGES ARE OFTEN PAINFUL

AT LEAST I FEEL SOMETHING

WHAT IS OSGI?

FORMERLY “OPEN STANDARDS GATEWAY INITIATIVE”

FOUNDED 1999 BY ERICSON, IBM, ORACLE, SUN MICROSYSTEMS

PROVIDES A STANDARD FOR SOFTWARE COMPONENTS AND EXECUTION ENVIRONMENT, WHICH IS BASED ON THE JAVA VIRTUAL MACHINE

THE PROBLEM

SMALL SYSTEMS BECOME LARGE COMPLEX SYSTEMS

MONOLITHIC BEASTS OF BURDEN

HIGHLY COUPLED

HARD TO TEST

HARDER TO DEPLOY

DOESN’T MAVEN/IVY SOLVE THAT?

MAVEN PROVIDES BUILD TIME MODULARITY

OSGI PROVIDES DEPLOY/RUN TIME MODULARITY

OSGI SUPPORTS MULTIPLE VERSIONS OF MODULES

THE SOLUTION

LIVE DEPLOYMENT OF BUNDLES AT RUNTIME

MULTIPLE VERSIONS OF BUNDLES CONCURRENTLY

DIFFERENT BUNDLES -CAN- SEE DIFFERENT VERSIONS

BUNDLE LIFECYCLE

WHAT DOES IT LOOK LIKE?

BORROWED FROM WIKIPEDIA

REMEMBER KERRYQUEUE?

SIMPLE THREAD BASED QUEUE

JOBS GO IN

JOBS COME OUT

COMMAND LINE DRIVEN

LETS BUNDLE IT!

BUILD A DISTRIBUTABLE JAR FILE

DEPLOY IT TO FELIX

W00T - BUT IT DOES NOTHING!

TIME FOR ACTIVATION

IMPLEMENT THE BUNDLE ACTIVATOR INTERFACE

ADD A MANIFEST TO THE JAR

ORGINAL ENTRY POINT

public class Main {

public Main(InterestingData interestingData) { this.interestingData = interestingData; }

public static void main(String[] args) { Main main = new Main(new InterestingData()); main.startWorkers(args[0]); }

private void startWorkers(String instance) { Thread workerThread = new Thread(new WorkerThread(interestingData)); workerThread.start();

int count = 20; for (Integer i = 0; i < count; i++) { interestingData.pushStuffIntoQueue(instance + "-" + i); } }}

BUNDLE ENTRY POINT

public class KerryActivator implements BundleActivator {

WorkerThread worker;

public void start(BundleContext bundleContext) throws Exception {

InterestingData interestingData = new InterestingData();

worker = new WorkerThread(interestingData); new Thread(worker).start();

int count = 20; for (Integer i = 0; i < count; i++) { interestingData.pushStuffIntoQueue( bundleContext.getBundle().getBundleId() + "-" + i); } }

public void stop(BundleContext bundleContext) throws Exception { System.out.println("So long... thanks for all the fish."); worker.terminate(); }}

MANIFEST

Import-Package: org.osgi.frameworkBundle-Activator: kerryQueue.KerryActivator

SCALA ANYONE?package com.theoryinpractise.scalabundle;

import org.osgi.framework.{BundleActivator,BundleContext}

class ScalaActivator extends BundleActivator { def start(bundleContext: BundleContext) = { System.out.println("Hello from scala") }

def stop(bundleContext: BundleContext) = { System.out.println("Goodbyte from scala") }}

SCALA ANYONE?<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.theoryinpracise.scalabundle</groupId> <artifactId>scalabundle</artifactId> <packaging>bundle</packaging> <version>1.0-SNAPSHOT</version> <name>scalabundle</name>

<repositories> <repository> <id>scala-tools.org</id> <name>Scala-tools Maven2 Repository</name> <url>http://scala-tools.org/repo-releases</url> </repository> </repositories>

<pluginRepositories> <pluginRepository> <id>scala-tools.org</id> <name>Scala-tools Maven2 Repository</name> <url>http://scala-tools.org/repo-releases</url> </pluginRepository> </pluginRepositories>

<dependencies> <dependency> <groupId>org.apache.felix</groupId> <artifactId>org.osgi.core</artifactId> <version>1.0.1</version> </dependency> <dependency> <groupId>org.scala-lang</groupId> <artifactId>scala-library</artifactId> <version>2.7.1</version> </dependency> </dependencies>

SCALA ANYONE? <build> <sourceDirectory>src/main/scala</sourceDirectory> <testSourceDirectory>src/test/scala</testSourceDirectory> <plugins> <plugin> <groupId>org.scala-tools</groupId> <artifactId>maven-scala-plugin</artifactId> <executions> <execution> <goals> <goal>compile</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.felix</groupId> <artifactId>maven-bundle-plugin</artifactId> <extensions>true</extensions> <configuration> <instructions> <Private-Package>com.theoryinpractise.scalabundle.*, scala.*</Private-Package> <Bundle-Activator>com.theoryinpractise.scalabundle.ScalaActivator</Bundle-Activator> </instructions> </configuration> </plugin>

</plugins> </build></project>

LINKS

HTTP://WWW.OSGI.ORG

HTTP://EN.WIKIPEDIA.ORG/WIKI/OSGI

HTTP://FELIX.APACHE.ORG

HTTP://NEILBARTLETT.NAME/BLOG/OSGIBOOK/