Embracing Groovy

Actually it's not that much about Groovy than it is about scripting.
After a yearlong battle I finally got my way and we added scripting capabilities to the Rifidi Emulator.
Scripting became an important issue as the scenarios we wanted to create grew more and more complicated.
Now that we also have to support RSSI (Received Signal Strength Indication) we need to be able to simulate tons of different reads with varying tag properties. Something that simply wasn't possible in TagStreamer.
So finally the management agreed that we had to include scripting support.
I already had quite clear picture of what I wanted to achieve and how the thing should look in the end.
So here is a quick outline how Groovy got hooked up to the emulator.

1. At first we had to get rid of the PlugIn-Registry from Eclipse. We were using extension points to register the different reader implementations but decided to be OSGi compliant a while back. We ripped out the registry and replaced it with OSGi-Services and Spring.
2. The nice guys at Groovy were kind enough to already ship an OSGi-enabled jar. So I just downloaded the current binary distribution and put groovy-all.jar into our target platform.
3. We took our RMI interface that we had added to allow TagStreamer to use Emulator instances remotely and refactored it a little.
   We basically made it more scriptable by exposing a couple of helper functions for creating tags and managing readers.
4. Integrating groovy with the new interface was the easiest part:
   Using the executor pattern we start a new Groovy Shell for each script. Each script gets a reference to the reader management service injected and can now create/destroy/start/stop... readers and tags.
5. Now to the part that I like the most:
   We have been using the Equinox-OSGi-console for quite some time now and we love how extensible this little bugger is. We added a couple of new shell commands to manage the scripts.

That's it. 5 days of work and we got full scripting into the emulator. It's not perfect but it will be improved while we use it.
Things we need to work on:

• Integrate with Eclipse (We want to make use of the great tooling Groovy has there)
• Integrate with Edge Server UI.
  
• Start distributing scenarios.

But for now I am quite happy with what we got :)

Exporting an OSGi application from Eclipse

Sometimes working with Eclipse feels like arcane science.
Creating a pure OSGi (Equinox) application is as easy as it can get.
Running and tuning are dead simple. Manipulating the runlevels works like a charm (needed to get load time weaving integrated).
But then try exporting it.
After a little painful research and some nice hints from the newgroup I got the following process:

1. Create a product from your launch config.
2. Open the product and go the configuration-tab. You will only see the bundles that were designated to be auto-started at a certain level. Add all other bundles and set them to auto-start at level 4. The funny thing here is that these are the default settings for every OSGi-Framework application, but in a product the default is to not auto start anything.
3. Now make sure that all fields on the overview-tab are blank (Application has always a preselection, at least on my install)
4.  If you haven't done so before add org.eclipse.simpleconfigurator to be started in level 1.
5. Start the Export Wizard.
   
6. Make sure that "Synchronize before exporting" is UNSELECTED, otherwise the export will fail.
7. Export.
8. If you don't have the delta in your target platform you will now have to copy the native fragments into the export.

There you go.