Is there a way to dynamically lookup EJB interfaces, comparable to CORBA's dynamic invocation interface (DII)?

Each EJB class has an associated EJBMetaData class that can be retrieved from the Home interface of the bean.

Home interfaces are published in JNDI, so they can also be discovered.

In particular, the javax.ejb.EJBMetaData interface provides methods such as getHomeInterfaceClass() and getRemoteInterfaceClass()

One thing that you will have to consider is using an EJB server that support dynamic stub downloading, so that you can make remote calls to the EJB.