What is a middleware for?

Question

I see in some courses some people highlight something like a middleware, example: middleware(authentication, authorization). I found the explanation rather superficial because it was not focus of the course, I ended up not understanding very well what is a middleware.

• After all what is a middleware?
• What are the existing middleware types?
• What good is?

Answer 1

After all what is a middleware? What is the point?

Well, we can answer these two questions together: a middleware is, saying in very simple terms a layer in the middle of two applications, that is, a layer that helps two applications, parts, systems, to communicate.

It serves to facilitate or make viable this communication. We think of interfaces, convert data and formats, provide protocols, among others.

It then serves to provide or facilitate communication between two applications, which may be of different platforms and different technologies.

An interesting image that illustrates this, is this:

Source: Is-an-API-considered-middleware

Interesting thing about this picture is that it shows a API as a middleware, that is, provides an intermediate layer for communication, for example between a company service and an external user.
See, here is just illustrating, as an example, an API working as a middleware, but both are separate things.

What are the existing middleware types?

There is no clear definition of what types of middleware, I have read about it and each source has a definition. Not thinking of types but, where these types of applications are most common, we could list:

• Operating Systems: are the middleware used in communication of core of an OS and the applications that run it (services, drivers, Dlls).
• Distributed systems: where applications provide the interfaces of communication between different systems (API, ESB, ODBC, OLEDB) making the role of middleware.
• Equipment: mainly with the emergence of Iot (Internet of things), where equipment needs to use a layer to communicate with other equipment and systems, middleware are surely present.

^{What is middleware?}

^{What is middleware?}