Middleware News Brief (MNB) features news and technical information about Open Source middleware technologies.
Java Remote Method Invocation (RMI) has the advantage of making distributed computing available to a large number of Java programmers without a significant learning curve, but it has its limitations.
RMI's primary limitation is the same as its greatest advantage, namely that all coding is done in Java. That's not a problem for a pure Java application. It is a problem for an application requiring integration with a code base of legacy C++ or COBOL. It's also a problem for an application that would like to take advantage of scripting languages such as Perl or Python for distributed administration tasks such as process monitoring. It's even a problem for a pure Java application with a long lifespan; eventually the system may have distributed components written in other languages. Most significant Java applications fall into one of those three categories.
The Object Management Group's (OMG) Common Object Request Broker Architecture (CORBA) is a specification for a distributed, object-oriented computing infrastructure. The OMG makes the CORBA specification freely available to anyone that wishes to implement it in any supported language. As a result, there are a wide variety of compliant CORBA implementations for many hardware platforms, operating systems, and languages.
Like RMI, CORBA's goal is to enable the development of distributed, object-oriented computing systems. CORBA extends its reach beyond Java, into languages such as C++, C, Ada, Smalltalk, Lisp, Python and Perl. CORBA's COM-to-CORBA bridge goes beyond that, extending CORBA's reach into languages such as Visual Basic, Delphi, and PowerBuilder.
Additionally, there are server-side benefits to using CORBA. CORBA's server-side Portable Object Adapter (POA) enables a server-side developer to separate the concept of an object reference, or proxy, as seen by the client from that of a servant, or implementation object, as seen by the server. This additional level of indirection places a great deal of power in the hands of a server-side developer.
The CORBA specification specifies a wire protocol called the Internet Inter-ORB Protocol (IIOP). This protocol is provided in every compliant implementation of the CORBA specification regardless of language.
RMI over IIOP combines the ease of use of the Java-based RMI programming model with the flexibility and power of CORBA and the language-independent IIOP protocol. In this middleware-focused SETT article, you'll learn how to leverage this powerful toolset to access the widest possible variety of clients without requiring client-side code changes.
Software Engineering Tech Trends (SETT) is a regular publication featuring emerging trends in software engineering.
