OSGi Event Admin with Spring DM

In my current post, I will try to highlight using event admin with spring DM. By an example, we will send an event inside the OSGi container from a notifier bundle and intercept by second subscriber bundle.

1 - Notifier Bundle

 

•  It contains a single Activator class.

•  Get an Event Admin service.

•  Send an event every 30 seconds.

•  An event is according to JTUNISIe queue and containing the current step and time stamp.

 

view source

print ?

01. package com.jtunisie.osgi.event.notifier.impl;

02.  

03. import java.util.Date;

04. import java.util.Properties;

05. import org.osgi.service.event.Event;

06. import org.osgi.service.event.EventAdmin;

07. import org.springframework.osgi.extensions.annotation.ServiceReference;

08.  

09. public class Activator {

10.  

11.      private String EVENT_QUEUE;

12.  

13.      protected void init() throws InterruptedException {

14.          Properties props = new Properties();

15.          int i= 0 ;

16.          while ( true ) {

17.              props.setProperty( "property" , "" +i+++ " : " + new Date());

18.              eventAdmin.sendEvent( new Event(EVENT_QUEUE, props));

19.              Thread.sleep( 30 * 1000 );

20.          }

21.      }

22.      private EventAdmin eventAdmin;

23.  

24.      @ServiceReference

25.      public void setEventAdmin(EventAdmin eventAdmin) {

26.          this .eventAdmin = eventAdmin;

27.      }

28.  

29.      public void setEVENT_QUEUE(String EVENT_QUEUE) {

30.          this .EVENT_QUEUE = EVENT_QUEUE;

31.      }

32. }

 On the spring config file we just call the init method after bundle starting :

view source

print ?

01. <?xml version= "1.0" encoding= "UTF-8" ?>

02. <beans xmlns= "http://www.springframework.org/schema/beans "

03.    xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance "

04.    xmlns:osgi= "http://www.springframework.org/schema/osgi "

05.    xsi:schemaLocation="http: //www.springframework.org/schema/beans

06.    http: //www.springframework.org/schema/beans/spring-beans.xsd

07.    http: //www.springframework.org/schema/osgi http://www.springframework.org/schema/osgi/spring-osgi.xsd "

08.    >

09.  

10.      <bean id= "activator" class = "com.jtunisie.osgi.event.notifier.impl.Activator" init-method= "init" >

11.          <property name= "EVENT_QUEUE" value= "JTUNISE" />

12.      </bean>

13.      

14.      <bean class = "org.springframework.osgi.extensions.annotation.ServiceReferenceInjectionBeanPostProcessor" />

15. </beans>

 

2 -  Subscriber Bundle

•  Contains a single Activator class

•  Implements EventHandler Interface

•  When an event is intercepted it prints the new property.

 

view source

print ?

01. package com.jtunisie.osgi.event.subscriber.impl;

02.  

03. import org.osgi.service.event.Event;

04. import org.osgi.service.event.EventHandler;

05.  

06. /**

07.   *

08.   * @author slim

09.   */

10. public class Activator implements EventHandler {

11.  

12.      private String property;

13.  

14.      @Override

15.      public void handleEvent(Event event) {

16.  

17.          String value = event.getProperty(property).toString();

18.          System.out.println( "value : " + value);

19.      }

20.  

21.      public void setProperty(String property) {

22.          this .property = property;

23.      }

24. }

 

Spring DM helps us to register our bundle as an event hander service and setting it to listen jtunisie queue.

 

view source

print ?

01. <?xml version= "1.0" encoding= "UTF-8" ?>

02. <beans xmlns= "http://www.springframework.org/schema/beans "

03.    xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance "

04.    xmlns:osgi= "http://www.springframework.org/schema/osgi "

05.    xmlns:osgix= "http://www.springframework.org/schema/osgi-compendium "

06.    xmlns:context= "http://www.springframework.org/schema/context "

07.    xsi:schemaLocation="http: //www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd

08.    http: //www.springframework.org/schema/context     http://www.springframework.org/schema/context/spring-context-2.5.xsd

09.    http: //www.springframework.org/schema/osgi-compendium http://www.springframework.org/schema/osgi-compendium/spring-osgi-compendium.xsd

10.    http: //www.springframework.org/schema/osgi http://www.springframework.org/schema/osgi/spring-osgi.xsd "

11.    >

12.    

13.  

14.      <bean id= "activator" class = "com.jtunisie.osgi.event.subscriber.impl.Activator" >

15.          <property name= "property" value= "property" />

16.      </bean>

17.  

18.    <osgi:service id= "activatorService" ref= "activator" interface = "org.osgi.service.event.EventHandler" >

19.          <osgi:service-properties>

20.             <entry key= "event.topics" value= "JTUNISE" />

21.          </osgi:service-properties>

22.      </osgi:service>

23.  

24.  

25. </beans>

 

3- Deployment

- Project is composed of one Maven project with two sub projects using Felix plug-in.
- At the deployment level we need :
   1- An OSGi container.
   2- Spring dependencies ( Extenders, beans ...) with spring-osgi-annotations

After installing the two bundles, the output should be the same as :

 

view source

print ?

01. osgi> value : 1 : Tue Nov 11 23:57:33 CET 2008

02. value : 2 : Tue Nov 11 23:58:03 CET 2008

03. value : 3 : Tue Nov 11 23:58:33 CET 2008

04. value : 4 : Tue Nov 11 23:59:03 CET 2008

05. value : 5 : Tue Nov 11 23:59:33 CET 2008

06. value : 6 : Wed Nov 12 00:00:03 CET 2008

07. value : 7 : Wed Nov 12 00:00:33 CET 2008

08. value : 8 : Wed Nov 12 00:01:03 CET 2008

09. value : 9 : Wed Nov 12 00:01:33 CET 2008

10. value : 10 : Wed Nov 12 00:02:03 CET 2008

11. value : 11 : Wed Nov 12 00:02:33 CET 2008

12. value : 12 : Wed Nov 12 00:03:03 CET 2008

13. value : 13 : Wed Nov 12 00:03:33 CET 2008

14. value : 14 : Wed Nov 12 00:04:03 CET 2008

 

Note : source code is under svn : svn checkout http://osgievent.googlecode.com/svn/trunk/ osgievent-read-only