Middleware "dark matter"

Clay Shirky describes PCs as the "dark matter of the Internet" because a lot of them are connected, but they're barely detectable. We can apply a similar analogy to middleware because the "mass" of the middleware universe is much greater than the systems - such as message-oriented middleware (MOM), enterprise application integration (EAI), and application servers based on Corba or J2EE - that we usually think of when we speak of middleware. We tend to forget or ignore the vast numbers of systems based on other approaches. We can't see them, and we don't talk about them, but they're out there solving real-world integration problems - and profoundly influencing the middleware space. These systems are the dark matter of the middleware universe.