Toward Integration Where is Middleware ?

T his column is all about middleware, and ultimately, middleware is all about integration. Middleware has existed in various forms for many years in systems such as the IBM Customer Information Control System (CICS), numerous message queuing systems such as IBM’s MQ Series, the Common Object Request Broker Architecture (Corba), Microsoft’s Component Object Model (COM), Java 2 Enterprise Edition (J2EE), and the latest rage, Web services. Virtually every form of application, programming language, operating system, and hardware has been a target of an integration effort involving these middleware systems or their cousins. Middleware is everywhere. The many reasons we need middleware all boil down to one: As technology continues to evolve at an accelerating rate, nontrivial computing systems will remain diverse and heterogeneous.1 Computing systems grow over time, which means hardware and applications purchased years ago must work together with those purchased just yesterday. Add factors such as mergers, reorganizations, leadership changes, and e-business into the picture, and the heterogeneity in the overall system rises sharply. As much as we might wish otherwise, the complexity caused by this diversity will not disappear anytime soon, if ever. We’re surrounded by examples of successfully deployed middleware in cost-effective and efficient production computing systems. Nevertheless, it’s interesting to note that while middleware eases the diversity and heterogeneity problem, it does not completely solve it. It’s ironic that all forms of middleware attempt to reduce complexity by introducing artificial homogeneity into the system, which only delays the inevitable collision between heterogeneous systems. The very ab-stractions and simplifications that allow middleware to address integration issues can also cause problems between middleware systems. After all, middleware systems differ from each other, and system administrators eventually need to integrate two or more systems that use different middleware.