Importing a OSGi service that is a singleton bean (that has a factory method) -

how import exported osgi service that's singleton bean?

i end getting exception follows:

unable start blueprint container bundle opaclient org.osgi.service.blueprint.container.componentdefinitionexception: unable find matching constructor on class com.opa.gateway.opagateway arguments [] when instantiating bean opagateway     @ org.apache.aries.blueprint.container.beanrecipe.getinstance(beanrecipe.java:336) 

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my blueprint xml service exported follows:

<bean id="opagateway" class="com.opa.gateway.opagateway" factory-method="getinstance"/> <service ref="opagateway" interface="com.opa.gateway.iopagateway" /> 

and service referenced in bundle follows:

<reference interface="com.opa.gateway.opagateway" component-name="opagateway" availability="mandatory" /> 

is there way directly reference singleton bean that's osgi service?

yes, can reference singleton osgi service. make sure (as @balazs suggested) class has static function/method getinstance() no arguments.

have @ blueprint below. hope gives clue... (if need complete sample can try post it.

<bean   id="opagateway"         class="org.test.opagateway" factory-method="getinstance"> </bean>  <bean id="opaclient"       class="org.test.client.opaclient"         init-method="startup"         destroy-method="shutdown"> </bean>  <service ref="opagateway" interface="org.test.iopagateway" />   <reference interface="org.test.iopagateway" availability="optional">     <reference-listener bind-method="setopagateway"                     unbind-method="unsetopagateway">         <ref component-id="opaclient"/>     </reference-listener> </reference> 

• bean opagateway (org.test.opagateway). class implementing org.test.iopagateway. instantiated static method getinstance():

  public class opagateway implements iopagateway {     private static opagateway instance = null;      public static opagateway getinstance () {         if(instance == null) {             instance = new opagateway();         }         return instance;     }      // simple method...     @override     public string printmessage() {         return "i opagateway";     } } 

• bean: opaclient: consumer or class references opagateway:

  public class opaclient {     public void setopagateway(iopagateway c) {         if(c != null) {             system.out.println("message: " + c.printmessage());         }     }     public void unsetopagateway(iopagateway c) {      } } 

• the reference-listener: injects instance of opagateway in opaclient using bind/unbind-method.

you can find more information here: http://www.ibm.com/developerworks/library/os-osgiblueprint/