ABSTRACT

This chapter compares different middleware technologies in terms of what they support. The Common Object Request Broker Architecture (CORBA) Naming service accepts a name from a client, maps that name to an IOR, and returns the IOR to the client. When talking about calling a specific distributed object, this is possible in Enterprise Java Beans (EJB) through the use of a Stateful Session Bean but it is not required—consider pools of Stateless Session Beans. In regard to Broadcast without message queue, any middleware can be used to do this, simply by keeping a list of recipients, and sending messages to all those recipients. All the middleware technologies are running on top of TCP/IP. They mostly require another protocol to run on top of TCP/IP—in the case of CORBA this is IIOP, in the case of the various web services this is Hypertext Transfer Protocol (HTTP), note that HTTP is really required for the RESTful web services.