What Is Middleware?

There are many definitions of middleware. Ultimately, the definition that works best defines middleware in terms of its function. Middleware is a mechanism that allows one entity (application or database) to communicate with another entity, or entities. In other words:

Middleware is any type of software that facilitates communication between two or more software systems.

Such a broad definition is necessary when you consider that middleware may be as simple as a raw communication pipe running between applications, such as Java's Remote Method Invocation (RMI), or as sophisticated as information-sharing and logic-execution mechanisms, such as Transaction Processing (TP) monitors.

Middleware's import role in the sharing of information means that its importance to the application integration solution is growing more evident. Once it was just a tool for moving information between systems existing within a single enterprise. Now we view middleware as a technology that allows us to move information between multiple enterprises. Middleware conceived and built exclusively for intraenterprise integration presents vendors with a significant challenge, given this new demand on the products.

It is a challenge vendors are anxious to meet. They are aware of the market benefit they will reap by supporting application integration. Of course, in their efforts to claim the marketplace, they are quicker to change their marketing message than they are to change their technology.