PHP

PHP is one of the most widespread scripting languages used to deploy Web applications. The rich features it offers combined with the natural easiness and the open source characteristics have made it the second most popular scripting language encountered on the Web [T]. Although there is a general intuition that PHP is mainly preferred for constructing small or medium sized applications, several large-scale Web sites serving hundreds of millions of users worldwide, such as Facebook, Wikipedia and Wordpress have been developed with it. Currently, PHP is installed on over 20 million sites and 1 million Web servers.

It was originally designed for the development of Web applications, in order to produce dynamic pages. PHP scripts can be embedded into HTML and they generally run on a Web server (server side scripting), which needs to be configured properly to execute PHP code. It can be deployed on most Web servers and on almost every operating system and platform.

PHP scripts are phrased by following a C-style coding syntax and all the allocated resources are released after the script execution by an automatic garbage collection mechanism. Since its fifth version, it also supports the object-oriented programming style by adopting principles such as abstract data types and information hiding, inheritance and polymorphism. Moreover, it includes features such as variables, arrays and associative arrays setting and manipulation, conditional statements, loops, function setting and file handling. Apart from these classic characteristics, PHP allows programming of the HTTP protocol by providing access to HTTP sessions and cookies and, furthermore, by implementing secure file uploads. One of the most robust features of PHP is its native support to MySQL. SQLite and PostgresSQL database systems. Through built-in functions and classes, PHP scripts can easily connect to database servers, submit queries and retrieve data. The combination of PHP and MySQL is one of the most common techniques currently employed by the developers when building Web applications.

Questionnaire:

• What is PHP? Explain.