An Introduction to Sockets in PHP

Introduction

In the vast and exciting terrain of network programming in PHP, working with low-level sockets can be a cumbersome task. Most of the time, when you are developing a Web application, you do not go very deep into the manipulation of the lower-level features of a network operating system.

If you've been using sockets in PHP, you probably know what I'm talking about. Writing, reading and controlling socket streams can be achieved well enough with the help of a comprehensive set of native PHP functions, such as the popular "fsockopen()", and "fputs()/fgets()" functions, and eventually the use of an iteration routine. This sounds relatively simple, and certainly will suit most of your socket programming needs. However, there are times when the requirements of a specific PHP project demand using low-level sockets, in order to implement, for example, a testing TCP-based server, and the corresponding client applications that will interact with it.

In order to tackle this kind of situations (and many more, by the way), luckily PHP offers a nice library of socket handling functions, which can be used to create server and client applications, manipulate data streams, and perform many more tasks related to low-level network programming. With reference to using sockets in PHP, in this three-part series, I'll try to cover their most crucial aspects. I'll start with the basics, such as creating, opening and closing a socket. Then I will proceed to using advanced approaches, such as implementing socket servers. Of course, I'll accompany this material with numerous hands-on examples.

At the end of this series, you should be equipped with a good grounding in how to use and manipulate low-level sockets in PHP, in order to expand your existing background of network programming.

Now that you know the topics that will be discussed over this series, it's time to leap forward and begin learning the fundamentals of low-level sockets in PHP. It's going to be instructive, so let's get started.