What is Application Programming Interface ( API ) ?

**Tarjan** · 28-03-2010

Hi,

I've been trying to read about the API. But I'm confused. I feel they are a group of classes but it is clear that an API would be tantamount to a library. I'm so confused, if anyone can explain what is an Application Programming Interface ( API ) in very simple language that would be a great help.

**blindsleeper** · 28-03-2010

An API (Application Program Interface, "programming interface" or "interface for programmatic access to applications') is a set of functions to access the services of an application, through a programming language.

An API can provide a certain level of abstraction to the developer that is to say that it hides the complexity of accessing a system or application by proposing a set of standard functions which only the parameters and return values are known. Thus, by analogy with a car, the driver did not know the mechanics of operating a motor vehicle in order to drive it. Only an interface consisting of a steering wheel, pedals (accelerator, clutch, brake), joysticks (blinking lights, gearbox) and buttons (warning, anti-fog, horn, etc..) Are accessible to him: he is a sense of the proposed interface to the user.

**Volodymyra** · 28-03-2010

The API is a modern concept of the modular application programming (precursor of object-oriented programming). In this context, in fact, every function of a program is partially autonomous insofar as it does on any other functional module or variable "global" program and is called by providing input parameters and ends using output parameters.

It follows that even under full external audit program can "call" one of its functions because its performance depends only on parameters given to it. Each "entry point" of the API program describes precisely this: the code word to use to apply such a function and pass parameters to this function so that it can operate.

**X-Ray** · 28-03-2010

There are two types, including:

One depends on the programming language; the sense that it is available only in certain programming language, based on the use of syntax and elements of this language to make it suitable for use in this context.

And the other independent of language, this means that it is written in a way that allows it to be used in many programming languages (typically, an assembly / C-level interface) and this pattern in the types of interfaces required code used in the API service is not associated with a particular process, or operating system, usually are available separately.

**Gluteus** · 28-03-2010

A programming interface is a communication interface between components of software. This is the set of calls to certain libraries that provide access to certain services from the processes and represents a method to achieve abstraction in programming, usually (though not necessarily) between levels or lower and upper layers of software. One of the main purposes of an API is to provide a set of functions for general use, for example, to draw windows or icons on the screen. In this way, developers benefit from the advantages of using their API functionality, avoiding the work program everything from scratch. The APIs also are abstract: the software that provides a certain API is usually called the implementation of that API.

**DllD** · 28-03-2010

Functions programming interfaces in Java

The programming interfaces may have multiple functions. For example, in J2EE, there are the following functions: