Can remote EJB clients use something other than RMI over IIOP, or is that the only support protocol?
According to the J2EE spec, RMI/IIOP is the proposed way of remotely interacting directly with an enterprise bean inside an EJB container. However, you can wrap that bean as a web service and access it using SOAP/HTTP (SOAP over HTTP). You can also use a MOM approach using JMS destinations (queues and topics) as another way of interacting with the functionality of the bean.