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Re: [virgo-dev] Would you like to try debugging a Gemini Blueprint issue (with ECF)?

Hi Dmitry,

On 2/5/2013 2:48 PM, Dmitry Sklyut wrote:

I looked over this issue and here is what can be done (all config examples are based on github example provided in the forum post).

First bad news: I don't think it can be done with vanilla Blueprint xml config.

Good news it can be done with a little help from ECF and change in configuration on the blueprint side.

greedy-proxying is the answer: http://www.eclipse.org/gemini/blueprint/documentation/reference/1.0.2.RELEASE/html/service-registry.html#service-registry:refs:collection:greedy-proxying

BUT for greedy-proxying to work - ECF must publish its proxy with all interfaces advertised in reference.getProperty(Constants.OBJECTCLASS).
Including org.eclipse.ecf.remoteservice.IRemoteServiceProxy

Hmm. I'm not sure if I understand what you are saying. ECF's remote service admin does create and import the proxy with all interfaces that are advertised in objectclass. If ECF's remote service admin is used (e.g. as per the ECF examples), this does happen...but it seems to me that Gemini is somehow pre-empting and/or circumventing the operation of the ECF Remote Service Admin on the import side (I'm not sure of this, it's just a hypothesis). With ECF's proxy creation and publishing, IRemoteServiceProxy will be automatically added to the proxy...whether or not it appears in objectclass...and this happens fine in the ECF remote service examples because the proxy creation and publishing is done via the ECF remote service admin importService call.

I think the best solution should be to let the ECF remote service admin create and publish the proxy on the consumer/import side. I'm still not sure why this isn't just happening in this case...as it does in the example code (without Gemini). I think it would/will be much preferable to have ECF create and publish the proxy (as it should for ECF-exported remote services) than to try to get blueprints impl to import remote services exported by blueprint (it seems that's what you are attempting to do below...but I might be mistaken about your intent though). In any event, my reading of the remote service admin spec allows multiple distribution providers co-exist and not interfere with each other...by only responding to the appropriate discovered remote services (i.e. those exported via a compatible config).


On blueprint side:

1. use spring osgi namespace and you can change <reference/> to a <list/> and enable greedy-proxying

Instead of <blueprint..></blueprint> use:

<beans xmlns="http://www.springframework.org/schema/beans";
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; xmlns:osgi="http://www.springframework.org/schema/osgi";
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/osgi http://www.springframework.org/schema/osgi/spring-osgi-2.0.xsd";>

Instead of reference <reference id="host" interface="org.eclipse.ecf.examples.remoteservices.hello.IHello" availability="mandatory"> <reference-listener bind-method="bindHello"> <ref component-id="consumer" /> </reference-listener> </reference>

Use list
<osgi:list id="hostInListWithGreedy"
greedy-proxying="true" cardinality="1..N">
<osgi:listener bind-method="bindHello">
<ref bean="consumer" />

Or use to specify 2 interfaces vs. 1.

<osgi:reference id="host" cardinality="1..1">
<osgi:listener bind-method="bindHello">
<ref bean="consumer"/>

2. Instead of osgi:reference or osgi:list - use bean configuration (something like this in spring bean style)

<bean id="host2" class="org.eclipse.gemini.blueprint.service.importer.support.OsgiServiceProxyFactoryBean">
<property name="availability" value="MANDATORY"/>
<property name="interfaces">
<property name="listeners">
<bean class="org.eclipse.gemini.blueprint.config.internal.adapter.OsgiServiceLifecycleListenerAdapter">
<property name="bindMethod" value="bindHello"/>
<property name="targetBeanName" value="consumer"/>
<!-- or -->
<property name="target" ref="consumer"/>

There is a similar bean for <list/> OsgiServiceCollectionProxyFactoryBean that can be configured with greedy-proxying also.

I don't think there is anything blueprint can do to expose org.eclipse.ecf.remoteservice.IRemoteServiceProxy without knowing that it exists if it is not in the OBJECTCLASS property.

Another way forward for now is to get the target service object from within Blueprint proxy.


ServiceReference nativeReference = ((ServiceReferenceProxy)serviceReference).getTargetServiceReference()

This way it is as naked as DS service object.

Hope this is all clear.  I forked the blueECF github project and will push changes to it later today.