Question

I inherited a codebase that offers similar services over two channels:

1. REST/HTTP – handled by annotated Spring controller
2. JMS – handled by a Message Driven POJO

Message structure on both channels is more or less similar, so there is a lot of redundant/duplicate processing logic in controller and JMS listener. One way to fix that is to extract common logic into another component and inject that component into both @Controller and JMS listener.

Lets say I don’t have time to do that for now. Is there a way I could inject controller into JMS listener and call the same controller methods that are automatically invoked by Spring’s dispatcher servlet when a REST request arrives. Since there is no XML configuration for controller, how can I get its reference for injection into JMS listener? I don’t want to create another controller bean with a different ‘id’.

Answer 1

One way to fix that is to extract common logic

It is not “one way“, it is the only way. Not only because injecting controller into JMS message listener is one of the most awkward things you can do you to your architecture. But also because Spring itself will not let you do this.

In Spring MVC there are actually two contexts: main one (where JMS listeners are declared) and DispatcherServlet (MVC) context. The latter is a child of the former which means it can access beans from main context (otherwise it wouldn’t be possible to access services and DAOs in controllers), but not the other way around.

Lets say I don’t have time to do that for now

The fact that your current architecture is rather poor does not justify making it much worse. Probably some developer in the past had no time to extract common logic, hence the duplication. Now you want to introduce very unusual dependency from JMS layer to web layer… I would rather live with duplication.

Since there is no XML configuration for controller, how can I get its reference

Just for the record, if your controller is named FooBarController, this:

@Resource
private FooBarController fooBarController;

might work, but fortunately not from parent to child context.