Callback and its role in Web development

Web development services use various computer-programming languages for the design of the websites and certain web application for websites, for example a shopping cart for E-commerce websites. Indeed a web site development services needs to opt for the most feasible, yet functional form of development methods, if it intends to serve the purpose of being cost effective to its clients. For example, a web development service in India would need to provide services in lines with the technological advancement in developed countries, but at a much lower cost than a web development service in those countries. For this to happen, intelligent decisions have to be made by the developers regarding the selection of programming languages and the usage of the right functions. Some of the most commonly used programming languages include C, C++, C#, Perl, Python, and ASP.Net and so on.

Callback

In computer programming, a callback is defined as an executable code, which is passed as an argument to another code. It permits a lower level software layer to call a function or subroutine defined in a higher-level software layer.

The callback function is highly useful in web applications, wherein suitable information has to be displayed in real-time response to the information retrieved from the user. The callback function proves to be apt for this purpose and is used along other programming patterns and functions to provide highly functional web applications.

Implementation of callback

The implementation of callback varies in different programming languages. Three variants are discussed below:

* C and C++ permit function pointers as arguments to other functions.
* Perl allows subroutine references.
* C#.Net framework facilitates a type safe encapsulating reference to manage pointer functions, which can be used for callback operations.

Callback functions are also used as a means to handle exceptions arising with low-level function, as a way to collect operational statistics in course of larger computations i.e. as a way to enable side effects in response to a particular condition.

Few types of callback
A pure call back function always returns the same value for a given value of inputs i.e. purely functional and is free of any observable side effects.

A predicate callback is a special case callback function. It is a pure callback function that accepts a single input value and returns a Boolean value. They are useful in filtering a collection of values for a given condition.