As part of the Tuscany plugin for Geronimo, I was looking at providing SCA services from session beans, and then started wondering if callback support for session beans makes sense. Here are some questions and comments I have:
1. If an EJB 3 business interface has an @Callback annotation on it, what does it mean when this EJB is invoked as a regular EJB, say from a Servlet. Does it mean that the Servlet will have to implement the callback interface? What happens when the Servlet invokes the EJB as an SCA service? 2. If there is no callback is injected when the EJB is invoked as an EJB, does the EJB implementation need to distinguish it is an EJB call and service the request or throw an error since no callback is available? 3. Even though the SCA JEE spec restricts that each EJB can be used as a component implementation at most once, when there are more than one component that has this EJB component as SCA reference target, the callbacks will have to be injected differently based on the component that is invoking the service. -- Vamsi
