Difference between protocol,middleware , web services and api?

Question

These terms seem to be very similar which confuses me a lot.
So far I know:

• A protocol is a set of rules,methods that allow communication between two systems, it is like a real life lenguage and the systems are the two people talking.
• An API is a software that allows communication from one system to another, it is like a waitress(API) that takes request from a client to the kitchen and sends back the response from the kitchen to the client.

• Web Servives are APIS that uses http protocol to communicate with the client and the server. In the previous example of the waitress, the http protocol would be the lenguage that the client,waitress and the kitchen use to communicate to each other.

• Middleware is the software that runs the API (?)

Am I right?

Answer 1

In simple terms,

Protocol can be considered as a law suit or common agreement between two or more parties (components) used for communication with each other. Most of the times protocol includes the steps and/or procedures that should used when communicating with each other.

API allows and defines how two applications can communicate with each other by using the methodologies defined by the service providing application. Compared to a protocol, API describes the programmatic ways to communicate in-between applications. Service calling application must properly adhere to the standards in order to get the required service.

Web services these are very similar to APIs. Notable thing with the web services is, developing a web service expects users to access it over the internet. Therefore web service can be considered as an online API.

Middleware allows to communicate with distributed application components located in several computers (Simply links the components located in various machines in order to get the full application capabilities). Middleware minimizes the developing effort by overcoming heterogeneous factors (OS, hardware, network equipment etc.). Middleware locates in between application (application components) and the OS.