Where can I find a working example of how to remotely invoke an OSGi service contained within Eclipse Virgo?

Can anyone point to a step-by-step tutorial on how to configure a remotely-accessible service contained within Eclipse Virgo 3.0x? I know that standards exist, etc., but I can find NO example which does not seem to contain a bunch of hand waving instead of specific steps along with working code/configurations to download. I don't care if the example uses Apache CXF, Eclipse ECF, or just about anything else. What I want is the equivalent of RMI in that both the transport and wire protocol are abstracted away behind what appears to both client and server-side developers as just plain Java (with some liberties taken).

Which bundles must be deployed into Virgo to support remoting? What Spring-ish configuration settings work? What jars must be on the client-side classpath? Etc, etc.?

Solution

I played around with Apache CXF DOSGI and got it working quite easily.

Download CXF single bundle distribution from here - I used 1.3.0.

Unzip Virgo (I used the kernel distribution for simplicity), copy CXF bundle to pickup, and start Virgo:

$ bin/startup.sh
[2012-04-04 14:17:33.011] startup-tracker              <KE0001I> Kernel starting. 
[2012-04-04 14:17:36.135] startup-tracker              <KE0002I> Kernel started. 
...
[2012-04-04 14:17:38.561] sync Event Dispatcher Thread <UR0001I> User region ready. 
[2012-04-04 14:17:39.565] fs-watcher                   <HD0001I> Hot deployer processing 'INITIAL' event for file 'cxf-dosgi-ri-singlebundle-distribution-1.3.jar'. 
[2012-04-04 14:17:40.060] fs-watcher                   <DE0000I> Installing bundle 'cxf-dosgi-ri-singlebundle-distribution' version '1.3.0'. 
[2012-04-04 14:17:40.570] fs-watcher                   <DE0001I> Installed bundle 'cxf-dosgi-ri-singlebundle-distribution' version '1.3.0'. 
[2012-04-04 14:17:40.593] fs-watcher                   <DE0004I> Starting bundle 'cxf-dosgi-ri-singlebundle-distribution' version '1.3.0'. 
[2012-04-04 14:17:43.498] start-signalling-1           <DE0005I> Started bundle 'cxf-dosgi-ri-singlebundle-distribution' version '1.3.0'.

Install and run ZooKeeper server according to these instructions - I used 3.4.3. See also the ZooKeeper instructions including how to create a configuration file.

Create a file org.apache.cxf.dosgi.discovery.zookeeper.properties containing:

zookeeper.host = 127.0.0.1

and copy to pickup:

[2012-04-04 14:29:51.385] fs-watcher                   <HD0001I> Hot deployer processing 'CREATED' event for file 'org.apache.cxf.dosgi.discovery.zookeeper.properties'. 
[2012-04-04 14:29:51.417] fs-watcher                   <DE0000I> Installing configuration 'org.apache.cxf.dosgi.discovery.zookeeper' version '0.0.0'. 
[2012-04-04 14:29:51.428] fs-watcher                   <DE0001I> Installed configuration 'org.apache.cxf.dosgi.discovery.zookeeper' version '0.0.0'. 
[2012-04-04 14:29:51.434] fs-watcher                   <DE0004I> Starting configuration 'org.apache.cxf.dosgi.discovery.zookeeper' version '0.0.0'. 
[2012-04-04 14:29:51.439] fs-watcher                   <DE0005I> Started configuration 'org.apache.cxf.dosgi.discovery.zookeeper' version '0.0.0'.

Unzip another copy of Virgo kernel,copy the CXF bundle and org.apache.cxf.dosgi.discovery.zookeeper.properties into pickup, and start with a different JMX port:
```
$ bin/startup.sh -jmxport 9876
```
That's it, but to check that it's working, the remaining steps run the greeter sample...
Install/start the greeter interface and implementation bundles into the first Virgo instance. The simplest way is to copy the interface bundle to repository/usr and then copy the implementation bundle to pickup.
Install/start the greeter interface and client bundles into the second Virgo instance. The simplest way is to copy the interface bundle to repository/usr and then copy the client bundle to pickup.
When the "Invoke Remote Greeter Service" window appears, enter a string (e.g. "foo") into the Name field and click "Invoke".
The first Virgo instance shows the following trace log messages (in serviceability/logs/log.log):
```
Invoking: greetMe(foo)
```

The second Virgo instance shows the following trace log messages:

[2012-04-05 14:14:56.766] INFO  Thread-29                    System.out                                                        *** Invoking greeter *** 
[2012-04-05 14:14:56.970] INFO  Thread-29                    System.out                                                        greetMe("foo") returns: 
[2012-04-05 14:14:56.971] INFO  Thread-29                    System.out                                                          Hola foo 
[2012-04-05 14:14:56.971] INFO  Thread-29                    System.out                                                          Bonjour foo 
[2012-04-05 14:14:56.972] INFO  Thread-29                    System.out                                                          Hoi foo 
[2012-04-05 14:14:56.972] INFO  Thread-29                    System.out                                                          Hello foo 
[2012-04-05 14:14:56.972] INFO  Thread-29                    System.out                                                        *** Opening greeter client dialog ***

Look in the service registry of the second Virgo instance.

osgi> vsh:service examine 245

Properties:
    endpoint.id:
        http://localhost:9090/greeter
    objectClass:
        org.apache.cxf.dosgi.samples.greeter.GreeterService
    service.id:
        245
    service.imported:
        true
    service.imported.configs:
        org.apache.cxf.ws

Publisher: cxf-dosgi-ri-singlebundle-distribution 1.3.0 [84]

Consumer(s):
    cxf-dosgi-ri-samples-greeter-client 1.2.0 [86]

A remote GreeterService has been published in the service registry.