What is middleware exactly?

I have heard a lot of people talking recently about middleware, but what is the exact definition of middleware? When I look into middleware, I find a lot of information and some definitions, but while reading these information and definitions, it seems that mostly all 'wares' are in the middle of something. So, are all things middleware?

Or do you have an example of a ware that isn't middleware?


Lets say your company makes 4 different products, your client has another 3 different products from another 3 different companies.

Someday the client thought, why don't we integrate all our systems into one huge system. Ten minutes later their IT department said that will take 2 years.

You (the wise developer) said, why don't we just integrate all the different systems and make them work together? The client manager staring at you... You continued, we will use a Middleware, we will study the Inputs/Outputs of all different systems, the resources they use and then choose an appropriate Middleware framework.

Still explaining to the non tech manager
With Middleware framework in the middle, the first system will produce X stuff, the system Y and Z would consume those outputs and so on.


Middleware is a terribly nebulous term. What is "middleware" in one case won't be in another. In general, you can expect something classed as middleware to have the following characteristics:

  • Primarily (usually exclusively) software; usually doesn't need any specialized hardware.

  • If it weren't there, applications that depend on it would have to incorporate it as part of their application and would experience a lot of duplication.

  • Almost certainly connects two applications and passes data between them.

You'll notice that this is pretty much the same definition as an operating system. So, for instance, a TCP/IP stack or caching could be considered middleware. But your OS could provide the same features, too. Indeed, middleware can be thought of like a special extension to an operating system, specific to a set of applications that depend on it. It just provides a higher-level service.

Some examples of middleware:

  • distributed cache
  • message queue
  • transaction monitor
  • packet rewriter
  • automated backup system