OSGi Intro

Features:
    modularity
    dynamic,” Plug and Play”
    extensionable
    these features are supported by OSGI, the meaning is that you don’t need realize those features yourself, what you need do is just use it

What is OSGi
    Dynamic Module System For Java
    JSR232, JSR291
    Universal Middleware
    Best practice guide and support for building modularity/dynamic/extensionable system
    Modularity with rule;
    Dynamic support for module, OSGI service, configuration;
    Extension support with OSGI service.

    In OSGI module compose of one or more bundles;
    Bundle is a normal jar file, the difference is its Manifest.mf file, OSGI add some special header info property to declarative bundle, such as:
    bundle-version, export-package, import-package

Who use OSGi
    IBM/Websphere, RSA
    BEA/microServices, All BEA product will be based on microServices
    Eclipse
    Apache/Struts 2
    Spring/Spring-OSGi
    Simens, Nokia, BMW, Cisco etc.
    SAP,Oracle,IONA etc. are interested in OSGi,and be OSGi EEG member

Intro
    Dynamic Module System For Java
    JSR 232, JSR 291

Modularity
    Define module in OSGI;
    Publish functions for other modules;
    Use functions provided by other modules.

Implementation
    1) Equinox
       OSGI R4 RI
       by Eclipse
       www.eclipse.org/equinox
       used by Eclipse RCP & other products
    2) Felix
       http://felix.apache.org

Define module in OSGI
    In OSGI module compose of one or more bundles;
    Bundle is a normal jar file, the difference is its Manifest.mf file,
    OSGI add some special header info property to declarative bundle, such as: bundle-version, export-package, import-package

Publish bundle
    add export-package header info to provide package for other bundles to use, such as cn.org.osgi.ppt.service;
    add Fragment-Host header info to provide all resources for host bundle to use;

    publish OSGI service for other bundles;
    Use BundleContext.registerService to register normal java interface as OSGI service;
    Export package cn.org.osgi.ppt.service

Use bundle
    A) Use BundleContext.getService to get OSGi service provided by other bundles;
    B) Add import-package header info to import packages provided by other bundles.

    add import-package header info to import packages provided by other bundles, then you can use the java class in those packages;
    add require-bundle header info to use all export packages and resources provider by bundle;

    use OSGi service provided by other bundles;
    A) Use BundleContext.getService to get OSGi service provided by other bundles;

Usage in Eclipse:
    1) New a plug-in project, Target Platform: an OSGi framework: Equinox
       Plug-in ID: OsgiHello
       Activator: com.zero.demo.osgihello.Activator
       Click finish.

       Implement Activator.start()
        public void start(BundleContext context) throws Exception {
            System.out.println("OsigHello started...");
            context.registerService(HelloService.class.getName(), new HelloServiceImpl(), null);
        }
      
       Define a interface: com.zero.demo.osgihello.HelloService
       Implement this interface: com.zero.demo.osgihello.HelloServiceImpl
      
       META-INF/MANIFEST.MF
         Export-Package: com.zero.demo.osgihello

    2) New a plug-in project OsgiHelloTest to invoke the OSGI bundle OsgiHelloHello.
       Target Platform: an OSGi framework: Equinox

       META-INF/MANIFEST.MF
        Require-Bundle: OsgiHello

       Implement Activator.start(): get the OSGI bundle OsgiHello.

        public void start(BundleContext context) throws Exception {
            System.out.println("OsigHelloTest started...");
            ServiceReference serviceRef = context.getServiceReference(HelloService.class.getName());
           
            if (serviceRef != null) {
                //Get the OSGI bundle
                HelloService helloService = (HelloService) context.getService(serviceRef);

                //Test the OSGI bundle
                String result = helloService.sayHello("Jerry");
                System.out.println(result);
            }
        }

       Click Run/Open Run Dialog...
       New a launch configuration under OSGi Framework
       In Bundles/Workspace, select OsgiHelloTest
       Click "Add Required Bundles"
       Click Run

Management lifecycle
    //Display all bundles
    osgi>ss

    ID  state   Bundle
    ----------------------------------------------------------
    0 ACTIVE  org.eclipse.osgi_3.3.0.v20070530
    1 ACTIVE  OsgiHello_1.0.0

    start/stop/update/uninstall Bundle.ID
    osgi>start 2
    osgi>stop 2
    osgi>update 2
    osgi>uninstall 2

Deploy outside alone
    Create equinox framework app outside alone first;
   
    1) create Equinox directory, then create configuration, plugins directory in Equinox directory;
    2) put org.eclipse.osgi.jar & org.eclipse.osgi.services.jar to plugins directory;
    3) create config.ini in configuration directory,content in config.ini like this:
        osgi.noShutdown=true
        osgi.bundles=org.eclipse.osgi.services_3.1.100.v20060601.jar@start
        osgi.bundles.defaultStartLevel=4
        osgi.configuration.cascaded=false
        eclipse.ignoreApp=true

    Create run.bat in Equinox directory,content in run.bat(windows) like this:
        @echo off
        java -jar plugins/org.eclipse.osgi_3.2.1.R32x_v20060919.jar -configuration configuration -console

    Install bundle
        osgi>install file:/C:\Equinox\OsgiHello_1.0.jar
        osgi>install file:/C:\Equinox\OsgiHelloTest_1.0.jar
   
    Use ss to see all installed bundles
    osgi>ss

    ID      state       Bundle
    -----------------------------------------------------------------
    0       ACTIVE      org.eclipse.osgi_3.3.1.R33x_v20070828
    1       ACTIVE      org.eclipse.osgi.services_3.1.200.v20070605
    12      INSTALLED   OsgiHello_1.0.0
    13      INSTALLED   OsgiHelloTest_1.0.0

    state       description
    ----------------------------------------------------------------------------------------------
    INSTALLED   the bundle was just installed, its state is INSTALLED, can start it.
    ACTIVE      after start a bundle, its state is ACTIVE, can update, refresh, stop, uninstall it
    RESOLVED    after stop a bundle, its state is RESOLVED, can start, uninstall it
    <<LAZY>>   

    If a bundle is installed, it's state is installed, can start it.
    If a bundle is uninstalled, it's state is
   
    start the installed bundles using 'bundle ID' or 'bundle name'
    osgi>start 12
    osgi>start 13

    or

    osgi>start OsgiHello
    osgi>start OsgiHelloTest

    If bundle OsgiHelloTest can't invoke/find bundle OsgiHello, refresh the bundle.
    osgi>refresh 13

    If bundle is updated, update it
    osgi>update 12

Valid commands:
---Controlling the OSGi framework---
launch - start the OSGi Framework
shutdown - shutdown the OSGi Framework
close - shutdown and exit
exit - exit immediately (System.exit)
init - uninstall all bundles
setprop <key>=<value> - set the OSGi property
---Controlling Bundles---
install - install and optionally start bundle from the given URL
uninstall - uninstall the specified bundle(s)
start - start the specified bundle(s)
stop - stop the specified bundle(s)
refresh - refresh the packages of the specified bundles
update - update the specified bundle(s)
---Displaying Status---
status [-s [<comma separated list of bundle states>]  [<segment of bsn>]] - display installed bundles and registered services
ss [-s [<comma separated list of bundle states>]  [<segment of bsn>]] - display installed bundles (short status)
services {filter} - display registered service details
packages {<pkgname>|<id>|<location>} - display imported/exported package details
bundles [-s [<comma separated list of bundle states>]  [<segment of bsn>]] - display details for all installed bundles
bundle (<id>|<location>) - display details for the specified bundle(s)
headers (<id>|<location>) - print bundle headers
log (<id>|<location>) - display log entries
---Extras---
exec <command> - execute a command in a separate process and wait
fork <command> - execute a command in a separate process
gc - perform a garbage collection
getprop  { name } - displays the system properties with the given name, or all of them.
---Controlling Start Level---
sl {(<id>|<location>)} - display the start level for the specified bundle, or for the framework if no bundle specified
setfwsl <start level> - set the framework start level
setbsl <start level> (<id>|<location>) - set the start level for the bundle(s)
setibsl <start level> - set the initial bundle start level
---Controlling the Profiling---
profilelog - Display & flush the profile log messages

---Eclipse Runtime commands.---
diag - Displays unsatisfied constraints for the specified bundle(s).
---Controlling the Console---
more - More prompt for console output

Resource:
    Understanding how Eclipse plug-ins work with OSGi
    http://www.ibm.com/developerworks/library/os-ecl-osgi/index.html

    http://www.osgi.org
    http://www.osgi.org.cn
    http://www.aqute.biz
    http://blog.bluedavy.cn