Clean up your wire protocol with SOAP

by Tarak Modi

April 5, 2001 —

Many developers have run into this dilemma: A CORBA client needs to obtain the services of a Distributed Component Object Model (DCOM) client or vice versa. The common solution is to use a COM/CORBA bridge, however, this answer is fraught with failure points. Suppose you have just introduced a complex new piece of software in the midst of two already complicated pieces (the CORBA ORB and the COM infrastructure). The bridge's complexity results from the intricate back-and-forth translation that it must complete from CORBA's Internet Inter-ORB Protocol (IIOP) to DCOM's Object Remote Procedure Call (ORPC). Any changes to these protocols mean changes to the bridge. What if I tell you that SOAP can alleviate the problem? Interested?

SOAP stands for Simple Object Access Protocol. In a nutshell, SOAP is a wire protocol similar to the IIOP for CORBA, ORPC for DCOM, or Java Remote Method Protocol (JRMP) for Java Remote Method Invocation (RMI). At this point you may be wondering, with so many wire protocols in existence, why do we need another one. In fact, isn't that what caused the problem discussed in the opening paragraph in the first place? Those are valid questions, however SOAP is somewhat different from the other wire protocols.