Re: DS optional cardinality question

BJ, Roy,

Thanks for the responses. But I am still concerned:

• Based on the meta-data, the component "Manager" could come up and operate when a optional service that it has a reference to is not available. correct ? Does this mean, bootstrapping "Manager" should not automatically bootstrap "Listener1" and "Listener2" ? This is what I see happening right now. The model I have in mind is that the services "Listener1" and "Listener2" can be activated due to some other dependencies (unrelated to Manager), and when they do, they get injected into Manager. In my view, activating "Manager" should not activate all listeners. Can you explain the rationale for this behavior ?
• I do not want to use lookup strategy in my component because I want to avoid framework bleed into my component code. This is not a good choice for me. So, alternatively, is there a way to implement the collaborator pattern I described without using lookup strategy ?
  

Regards,
Subbarao

BJ Hargrave/Austin/IBM@IBMUS

BJ Hargrave/Austin/IBM@IBMUS
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Subject	Re: [equinox-dev] DS optional cardinality question

Yes. If you want to delay activating the listener component until they are 
actually needed, then you need to use the lookup strategy. 

BJ Hargrave
Senior Technical Staff Member, IBM
OSGi Fellow and CTO of the OSGi Alliance
hargrave-r/Jw6+rmf7HQT0dZR+AlfA@xxxxxxxxxxxxxxxx
Office: +1 407 849 9117 Mobile: +1 386 848 3788



Roy Paterson/Austin/IBM@IBMUS 
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2006-03-02 09:49 AM
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Re: [equinox-dev] DS optional cardinality question







I think this is working as designed.  Declarative Services will call the 
bind method on Manager before it calls Manager's activate Method.  It does 
not matter that the reference is optional.  The "optional" setting only 
controls whether the Manager will be activated or not - it has no bearing 
on the lifecycle of Listener1 or Listener2. 

Regards, 
Roy

-----------------------------------------
Roy Paterson
IBM Pervasive Computing
Austin, TX
Phone: (512) 838-8898



Subbarao Meduri/Durham/IBM@IBMUS 
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[equinox-dev] DS optional cardinality question








I have a simple collaborator pattern where a Manager component has a 
optional multiple reference to several Listener services as shown below:

<component 
name="Manager" immediate="true">
<implementation class="com.ibm.listener.Manager"/>
<reference
name="Listener"
interface="com.ibm.listener.Listener"
cardinality="0..n"
policy="dynamic"
bind="addListener"
unbind="removeListener"
/>
</component>

<component 
name="Listener1">
<implementation class="com.ibm.listener.Listener1"/>
<service>
<provide interface="com.ibm.listener.Listener"/>
</service>
</component>

<component 
name="Listener2">
<implementation class="com.ibm.listener.Listener2"/>
<service>
<provide interface="com.ibm.listener.Listener"/>
</service>
</component>

Components Listener1 and Listener2 are not immediate components, where as 
the Manager component is. I would think that DS will activate Manager 
component without having to activate Listener1 or Listener 2 as they are 
not immediate components, and they are not mandatory for Manager (0..n 
cardinality). However, when I ran this example (with M5 bundles), both 
Listener 1 and Listener 2 were activated and injected into Manager 
component. Could this be a bug ?

Regards,
Subbarao_______________________________________________
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