Hi Christian, good idea.
Just a note (in term of wording), it means that a command has to implement Action, which is not necessary the case. For instance, ActiveMQ command directly extend gogo AbstractCommand, which implements gogo Function. So using the whiteboard extender, in the Action generator (in ActiveMQ command wrapper, I used the same logic for Hadoop commands) has to expose Action as a service (which is actually the case using BlueprintContainerAware and the fact that the actual commands are describe in the BlueprintContainer).
Though, I wonder if we may not have some "side effects" with this approach, especially in term of thread isolation and classloading (just thinking, I have to take a deeper look).
I will take a deeper look without jet lag tomorrow ;) Regards JB On 02/15/2014 04:10 PM, Christian Schneider wrote:
Hi all, I have created an experimental whiteboard extender for Action objects to export them as commands. See: https://issues.apache.org/jira/browse/KARAF-2762 And this as an example: https://github.com/cschneider/Karaf-Tutorial/tree/master/db/command2 The idea is that you simply create the Action in code like today and export it as a service with the di framework of your choice. The action is then picked up by the whiteboard extender and exposed as a command. One problem with this approach was that we need to create a new Action instance for each call to the command. I have found a simple way to do this. Basically I simply do class.newInstance() and copy all field values from the template. I also found a way to define completers. I simply check the Action for fields of type Completer and add these to the list of completers. I think this approach has some advantages compared to the DSL model Guillaume proposed. 1. We have very loose coupling as the use only needs to use interfaces and annotations 2. The solution is framework agnostic. You can use this model with blueprint, ds, plain OSGi API, ... 3. You can leverage the dependency injections of your framework. Even the completers can be injected which is nice if they need services to work. What do you think? Christian
-- Jean-Baptiste Onofré [email protected] http://blog.nanthrax.net Talend - http://www.talend.com
