OSGi Event Admin with Spring DM

最新推荐文章于 2025-12-06 11:19:53 发布

最新推荐文章于 2025-12-06 11:19:53 发布 · 183 阅读

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本文通过实例展示了如何使用Spring DM与OSGi容器内的事件管理服务(EventAdmin)进行交互。具体包括从通知者模块发送事件及由订阅者模块接收并处理这些事件的过程。

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.

 
   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 :

 
   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.

 
   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.

 
   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 :

 
   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