creating a pojo/ejb with spring 3 that always runs in the background

I have created apps in the past that would have web pages that would call the persistence layer to get some query results or to insert, delete, etc against a db. However, nothing was left running in the background except for the persistence layer. Now I need to develop an app that has an process that is always running in the background, which is waiting for messages to come thru a zeromq messaging system (cannot change this at this point). I am a little lost as to how to setup the o开发者_如何学编程bject so that it can always be running and yet I can control or query the results from the object.

Is there any tutorial/examples that covers this configuration?

Thanks,

You could use some kind of timer, to start a method every second to look at a specific ressource and process the input taken from that. If you use Spring than you could have a look at the @Scheduled annotation.

If your input is some kind of java method invokation, than have a look at the java.util.concurrent Package, and concurrent programming at all. -- But be aware of the fact, that there are some restictions one creating own Threads in an EJB environment.