Namespaces question

Question

I have been converting some code I had over to the new ExtensibleEnvironment stuff and this has been going quite well. Everything I have done so far has been to configure stand-alone things like message listerners etc. What I cannot figure out is how to do something that needs to be triggered in response to an "event" (in particular creation of a cache).
For example, suppose I want to configure custom indexes. I might do the following:
    <cache-mapping>
      <cache-name>dist-*</cache-name>
      <scheme-name>dist-default</scheme-name>
      <idx:indexes>
        <idx:index ordered="true">
          <idx:extractor>
            <instance:class classname="my.package.SomeExtractor"/>
          </idx:extractor>
          <idx:comparator>
            <instance:class classname="my.package.SomeComparator"/>
          </idx:comparator>
        </idx:index>
        <idx:index ordered="false">
          <idx:extractor>
            <instance:class classname="my.package.AnotherExtractor"/>
          </idx:extractor>
        </idx:index>
      </idx:indexes>
    </cache-mapping>At the moment the XML is processed as everything starts up but I only want to actually create the indexes when an instance of a cache is created (in the example above any cache with a named prefixed with "dist-".
Is there anything in the new Incubator release to allow me to do what I want or will I need to come up with my own solution? Is this what the Events or Dependencies packages are for; if it is can I see some documentation or an example?
Cheers,
JK

Answer 1

Jonathan,
As part of processing your namespace you can register resources with the Environment that implement the DependentResource interface.
Your registered resource will then be queried for its dependencies by calling the getDepedencyReferences method.
    public Set<DependencyReference> getDependencyReferences();When the dependencies are satisfied, the onDependenciesSatisfied method will be called by the Environment.
This mechanism is mainly there to allow you to manage dependencies when starting and shutting down a system properly, and not to provide a callback while the system is running.
One DependencyReference that might be useful for you is the NamedCacheReference which will be satisfied when the underlying cache service is started. You can find example uses of the DependentResource mechanism in the Processing Pattern.
Unfortunately, there is no way of getting an event when a cache is created which was what you really were looking for.
/Christer
Edited by: Christer Fahlgren on Mar 4, 2010 2:10 PM