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Re: [ecf-dev] Debugging RFC 119

Hi Bryan,

Bryan Hunt wrote:
Scott,

Thank you so much for the quick reply. I set auto_start to true on the ecf.osgi.* bundles (I own the product, so I get to set auto_start), and I got the server to work, but not after a bit of debugging.

When thie following code in DefaultHostContainer is executed:

IContainer[] containers = Activator.getDefault().getContainerManager()
.getAllContainers();
if (containers == null || containers.length == 0)
return null;

containers.length == 0 which causes the function to return null. That in turn causes:

for (Iterator i = rsContainers.iterator(); i.hasNext();) {
IRemoteServiceContainer rsContainer = (IRemoteServiceContainer) i
.next();

to throw an NPE.

This is a small bug in the DefaultHostContainerFinder class (i.e. improper handling of null returned from the function causing the NPE). Yes a new bug would be helpful on this.

The root cause of the problem is the start order of my bundles. The DS bundle is registering my service and ECF is trying to process the service before the bundle that constructs the container with:

Activator.getDefault().getContainerManager(1000).getContainerFactory().createContainer("ecf.r_osgi.peer");

is started.  Would you consider this a bug?  If so, I'll open a bugzilla.

I don't consider the bundle start order issue an ECF bug...as we can't control or dictate the start order.

Is it possible for you to call the Activator.getDefault().getContainerManager(1000).getContainerFactory().createContainer("ecf.r_osgi.peer"); before registering your remote service? There are a couple of ways to do this with DS I believe.

Scott


On May 19, 2009, at 11:34 AM, Scott Lewis wrote:

Hi Bryan,

Bryan Hunt wrote:
I'm trying to get ECF working with R-OSGi / RFC 119 and I'm having some difficulty. I'm trying to use transparent mode with declarative services. I've declared my service with the property: ogsi.remote.interfaces = * and I'm starting my application with:

Activator.getDefault().getContainerManager(1000).getContainerFactory().createContainer("ecf.r_osgi.peer");

My launch configuration includes the following ECF bundles:

org.eclipse.ecf
org.eclipse.ecf.discovery
org.eclipse.ecf.identity
org.eclipse.ecf.osgi.services
org.eclipse.ecf.osgi.services.discovery
org.eclipse.ecf.osgi.services.distribution
org.eclipse.ecf.provider
org.eclipse.ecf.provider.discovery  auto_start = true
org.eclipse.ecf.provider.jmdns  auto_start = true
org.eclipse.ecf.provider.jslp  auto_start = true
org.eclipse.ecf.provider.r_osgi
org.eclipse.ecf.provider.remoteservice
org.eclipse.ecf.provider.sharedobject

When I launch my app, my service gets registered, but there are no other bundles using that service. I was expecting one of the ecf bundles or R-OSGi to be using the service.

The problem is likely that that these three bundles:

org.eclipse.ecf.osgi.service
o.e.e.o.services.discovery
o.e.e.o.services.distribution

are never *started*, and so are not 'kicking in' to handle the remote service registration. There are two solutions to this:

1) explicitly start these bundles (not particularly recommended)
2) Refer to a class in services.distribution (and this will start distribution and the other two). This could be as simple as referring to

org.eclipse.ecf.osgi.services.distribution.IDistributionConstants

e.g.:

IDistributionConstants.REMOTE_INTERFACES and/or IDistributionConstants.REMOTE_INTERFACES_WILDCARD

OR

you can use some of the listener/notification interfaces we've created (that allow listeners to be notified about various parts of the distribution and discovery)...e.g.

org.eclipse.ecf.osgi.services.distribution.IHostDistributionListener (for receiving notification about service host events ...e.g. remote service registration) org.eclipse.ecf.osgi.services.distribution.IProxyDistributionListener (for receiving notification about service proxy events...e.g. proxy creation and registration)

If you setup/use these notification interfaces the bundles will be started automatically...and the listeners will then allow you to see/debug what's happening (along with the discovery listeners as well). The way these listeners are used is via registering a service that implements these interfaces...e.g.

bundleContext.registerService(IHostDistributionListener.class.getName(),myHostDistributionImpl,null);

Then at remote service registration time (i.e. when you register your own remote service), the hostDistributionListener will be notified. This is the service registry 'whiteboard' pattern.

FYI there is test code for the listeners in org.eclipse.ecf.tests.osgi.services.distribution/org.eclipse.ecf.tests.osgi.services.distribution.AbstractServiceRegisterListenerTest (and subclasses)

BTW, just as an aside, we (ECF) can't start these bundles in Eclipse automatically...i.e. as part of Eclipse startup...as explicitly starting bundles at Eclipse startup is in the domain of the platform project only.


Am I missing something basic here? Are there any key breakpoints in ECF I can set to debug the problem?

To start, I would say it's probably better to use the listeners...because they provide notification of the crucial host/client events. If you wish to go further with setting breakpoints, etc then the following classes provide the basic implementation and you are of course welcome and encouraged to debug into them.

Service Host: org.eclipse.ecf.internal.osgi.services.distribution.EventHookImpl (the service event hook impl, which is responsible for finding distribution providers/IHostContainerFinder, and then registering the service remotely on appropriate IContainer instances). Service Consumer: org.eclipse.ecf.internal.osgi.services.distribution.DiscoveredServiceTrackerImpl (receives notifications from discovery, and uses discovery meta-data to lookup/create proxy, and register the proxy service in local service registry).

BTW, I'm working on documentation and test code as quickly as possible for all of this (i.e. the RFC119 impl of course, as well as the listeners, and container finders...which allow one to easily customize the selection/use of IContainers/remote service provider impls). If others are able/willing to help with this or contribute to it, please let me know.

Thanks,

Scott

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