Introduction to Maintaining the State of Applications with PHP Sessions

Introduction

Due to the fast evolution of Web programming, the stateless nature of the HTTP protocol brought many problems to certain Web applications that required maintaining their state across several HTTP requests. This demanded a rapid development of several mechanisms aimed at tackling this issue through diverse methods.

Particularly, in the universe of PHP programming, session management emerged as a direct response to the above mentioned problem, and currently this mechanism is being used by PHP developers worldwide, in cases where a Web application needs to keep track of its “state” during the occurrence of different HTTP requests.

Whether you’re a beginner developer or an experienced PHP programmer, it’s quite probable you’ve already used some of the built-in functions included within the PHP session management module, when constructing user authentication systems, shopping carts or web-based email applications, to name a few illustrative cases.

Indeed, PHP sessions are very simple to use. They hide all the complexities inherent to where and how to store session data, and provide developers with a transparent mechanism for managing information that must persist or keep state even if different HTTP requests are triggered across the same Web application.

Since PHP sessions are one of those things that sooner or later you must learn as a PHP developer, in this article I shall provide an overview of them. I will begin with the basics of how to use them, highlighting their strong points and weaknesses, and finally explore some of their most advanced concepts. By the end of this series, you should have all the knowledge that you need to start using the most common PHP session management functions, so you can use them during the development of your own applications.

With the preliminaries out of the way, it’s time to move on and start out exploring the features of the session management mechanism in PHP. Let’s get going!