Re: [ecf-dev] Remote OSGI services over XMPP

[Scott Lewis <slewis@xxxxxxxxxxxxx>]

Hi Leen,

Leen Toelen wrote:
> Hi,
>
> I am trying to set up a network with lots of automatic bots that 
> basically need to expose their OSGI services to an administrator. I am 
> using XMPP as the protocol, and sending IM's and files work without a 
> problem. I would like to try remote services as well, but can't get it 
> working.
>
> This is what the bots do when admin comes online:
>
>     /**
>      * Register remote services with the admin
>      * This is called when admin comes online
>      */
>     private void initializeRemoteServices() {
>         try {
>             // Get ECF adapter for remote services
>             IRemoteServiceContainerAdapter adapter = 
> (IRemoteServiceContainerAdapter) container
>                     .getAdapter(IRemoteServiceContainerAdapter.class);
>
>             // This is the ID of the administrator
>             ID[] targetIDs = new ID[] { getID("admin") };
>
>             Dictionary props = new Hashtable();
>             props.put(Constants.SERVICE_REGISTRATION_TARGETS, targetIDs);
>             props.put(Constants.AUTOREGISTER_REMOTE_PROXY, "true");
>            
>             // Create service instance
>             PlatformAdmin service = Platform.getPlatformAdmin();
>            
>             IRemoteServiceRegistration reg = 
> adapter.registerRemoteService(new String[] { PlatformAdmin.class
>                     .getName() }, service, props);
>             System.out.println("Registered remote service server: "+reg);
>         } catch (Exception e) {
>             e.printStackTrace();
>         }
>     }
>
> The admin uses the normal contacts view, and has an action to use this 
> services when right-clicking on a bot. This is the code that tries to 
> connect to the PlatformAdmin service oof the selected bot:
>
> ID[] ids = new ID[] { entry.getUser().getID() };
> IRemoteServiceContainerAdapter adapter = 
> (IRemoteServiceContainerAdapter) 
> container.getAdapter(IRemoteServiceContainerAdapter.class);
> IRemoteServiceReference[] refs = 
> adapter.getRemoteServiceReferences(ids, PlatformAdmin.class.getName(), 
> null);
>
> But this always gives an empty array.

Hmmm.  This looks right.  But one possibility...*when* is the line on 
the bot that runs:

IRemoteServiceContainerAdapter adapter = 
(IRemoteServiceContainerAdapter) 
container.getAdapter(IRemoteServiceContainerAdapter.class);

Invoked for the first time?  Is it just prior to the line above? 

Because the adapter is initialized for receiving the remote service 
registrations *when the 
container.getAdapter(IRemoteServiceContainerAdapter.class) is called for 
the first time*.  This is because the adapter manager (the way that the 
remote service container adapter is associated with the xmpp container), 
is lazy...and so the code that sets up to *receive* service 
registrations may not be getting called until after the service 
registration has already occurred.

So if you could move the container.getAdapter call (in the client/bot) 
to either container creation time, or container connect time I think 
this might be solved.  If this turns out to be the case I will file a 
bug/enhancement request so that we can address it somehow in the 
underlying protocol so this isn't necessary.

> Is there something else I need to do to enable remote services on the 
> "client" side?

I think this may be it...moving up the 
container.getAdapter(IRemoteServicesContainerAdapter.class) call to 
earlier in the sequence.

BTW...also to be more like BundleContext.getServiceReferences, we've 
adjusted the adapter.getRemoteServiceReferences to return null instead 
of an empty array.  I prefer using empty arrays, but we are trying to 
make it as much like getServiceReferences as possible.

Thanks.  Please let us know if this is the issue.

Also...I happen to be working on a demo for using remote services to 
access the Equinox EnvironmentInfo service information.  Combined with 
the PlatformAdmin service this could be very interesting for providing 
remote support/problem diagnosis and repair.  Please let me know if you 
are interested in working on this in prep for EclipseCon (as I see you 
are providing remote access to PlatformAdmin...BTW...remember, that all 
method parameters and return values have to be Serializable to allow 
them to be sent over the wire...I'm not sure if this is true for 
PlatformAdmin's methods.

If you are interested in looking at the examples work see these three 
plugins:

<ecf 
root>/examples/plugins/org.eclipse.ecf.examples.remoteservices.common 
(defines IRemoteEnvironmentInfo interface)
<ecf 
root>/examples/plugins/org.eclipse.ecf.exmaples.remoteservices.server (a 
very simple Equinox process that registers an impl of 
IRemoteEnvironmentInfo)
<ecf 
root>/examples/plugins/org.eclipse.ecf.examples.remoteservices.client (a 
very simple client that uses the ECF discovery API to discover 
IRemoteEnvironmentInfo and then provides a serviceAccessHandler to hook 
into the service discovery view context menu...and allow the service to 
be connected to and then accessed via ECF IRemoteService methods (proxy, 
synch, asynch, future).

I'll have a wiki page with screen shots of this tomorrow.  In the 
meantime, here's the code in the CVS browser:

http://dev.eclipse.org/viewcvs/index.cgi/org.eclipse.ecf/examples/plugins/?root=Technology_Project

Scott


> Regards,
> Leen Toelen
>
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