Introduction

Most people who browse the Web are at least somewhat familiar with the term HTTP. At the very least, it is recognized as being the first part of most every location on the Web.

http://httphandbook.org/ is an example of a Uniform Resource Locator, often abbreviated as URL, which is a term that will be explained in detail later. Generally speaking, a URL specifies the location of a Web page. The first part of a URL, prior to the :// separator, specifies the protocol to be used. In most cases, as in this example, the protocol is HTTP, Hypertext Transfer Protocol.

So what is a protocol, exactly? A protocol, much as you might expect, is a set of formal guidelines or procedures that explain how to accomplish something. In the workplace, there may be a protocol for how to take a personal day or a week of vacation. Perhaps you have to fill out a form, get a manager’s signature, and then turn it in to the human resources department.

In the context it is used here, a protocol refers to a set of formal guidelines for communication between two computer programs. Of course, this type of protocol is much less flexible than what you may find in the workplace because computer instructions cannot be ambiguous or open for interpretation. Whereas people are flexible and can determine intent from ambiguity, computers require precise instructions and guidelines. For this reason, computer protocols must be very well defined and complete.

HTTP is the protocol that defines how the Web works, and that is the basis for this book. For some, HTTP may seem like an advanced topic that is only useful to the world’s top Web developers. However, I hope to soon dispel this myth and illustrate how a firm understanding of the Web’s fundamental architecture can be a huge benefit for Web developers of all levels and interests. In fact, I think this book can be quite a good introduction to developing for the World Wide Web. It is something that developers can make great use of over the course of their careers.

I have been developing for the Web since 1994. As with most people, I began by learning about the markup language HTML used for the layout of the pages. My local Internet Service Provider (ISP) provided me with Web hosting services, so I quickly had my own place on the Web.

For such simple endeavors, knowing HTML alone is sufficient. However, as the Web has become an important medium for business applications and communication, much more is expected of professional Web developers. In order to leverage the Web to its full potential, developers have been forced to gain insight into the Web as well as all the technologies that interact with it. A developer is expected to understand the fundamentals of networking, security, software architecture, server administration, database design and administration, as well as all the ways these aspects interact to make a Web application function properly.

Many books aspire to cater to both the beginner and the expert. In writing this book, I have found myself in the lucky position of being able to deliver just that. Prior to developing content for the Web, a potential developer can gain a great advantage by developing a strong foundation from which to build. By learning the fundamentals of the Web in the beginning, a developer can save a great deal of precious time avoiding the mistakes of others. This can also accelerate the learning process tremendously. Additionally, present Web developers might find their responsibilities expanding into other areas such as security, architecture, design, performance, reliability, and the like. Not only can a firm grasp of the fundamentals aid you in adapting to new responsibilities, it is important to have an essential reference that can reaffirm your Web expertise as you continue your professional career.