The Pollers - MDB, Singleton, Glassfish, JRuby

It has been a bit since last posting - has been a whirlwind since then. :)

Ended up utilizing MDBs to be able to get past the issue with the way the app was using the pollers to listen to certain events in the application (observer) and processing them.

Keeping the original logic in ruby, I ended up using a Singleton Bean to create and store a rails instance that was shared with the same VM as the rest of the app. Also slated this Singleton to be instantiated at Startup (@Startup) so it would be available when the rest of the app was ready:

@Singleton
@Startup
public class EIScriptingContainer {


With this, created a separate MDBs for each ruby poller, giving commands via the message selectors to determine which poller to utilize. This gave us the ability to use a central "SystemManager" to send messages to a Topic that the MDBs were listening to, and depending on the serviceName, would know what to do:

@MessageDriven(mappedName = "jms/SysMgrReq", activationConfig = {
    @ActivationConfigProperty(propertyName = "messageSelector", propertyValue = "serviceName='EventNotifier' AND messageAction IS NOT NULL"),
    @ActivationConfigProperty(propertyName = "acknowledgeMode", propertyValue = "Auto-acknowledge"),
    @ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Topic")
})

I then bundled all of these up in a single jar and deployed as an app to GF.

A big issue was the fact that sometimes we needed to have more than one instance of a poller running, but when re-loading the original script (via the JRuby ScriptingContainer), all of the Rails stack was loading. That was where the Singleton instance of the ScriptingContainer was created and pre-loaded with the rails environment, and this was utilized each time in the stopping, starting, starting additional instance, and refreshing these pollers.