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#Http client online software#

There are three versions of HTTP: 0.9, 1.0, and 1.1. In this chapter, we talk about each of the commonly used client request methods, and show you examples of their use. Although the most common request method is the GET method, there is also a handful of other methods that are supported by HTTP, and essentially define the scope and purpose of the transaction. Here we use the GET method to request the document /index.html using version 1.0 of HTTP. Then it sends a document request by specifying an HTTP command (called a method), followed by a document address and an HTTP version number. First, the client contacts the server at a designated port number (by default, 80).The client initiates the transaction as follows: HTTP is a simple stateless protocol, in which the client makes a request, the server responds, and the transaction is then finished. Structure of an HTTP TransactionĪll HTTP transactions follow the same general format, as shown in Figure 3-1. Although a few key phrases will help you get around town, fluency becomes very useful when you find yourself lost in the outskirts of the city. But it's all information you should know, so we recommend that you keep coming back to it. Furthermore, if you use LWP, then you can go pretty far without knowing more than a superficial amount of HTTP. This is one of the longest chapters in this book, and no doubt you won't read it all in one sitting. Headers give clients the opportunity to declare who they are and what they want, and they give servers the chance to tell clients what to expect.

Coverage of HTTP headers for both clients and servers.

These codes are the first indication of what to do with the server's response (if any), so robust client programs should be prepared to intercept them and interpret them properly.

Listing of server response codes, and discussion of the more common codes.

We also cover HTTP 1.1, the newest version of HTTP to date. For the most part, what you'll see is HTTP 1.0, but at least you'll know what that means. Clients and servers must declare which version of HTTP they use.

Summary of differences between various versions of HTTP.

Beyond GET, HEAD, and POST, we also give examples of the PUT, DELETE, TRACE, and OPTIONS methods.

Discussion of the request methods clients may use.

This section also serves as a sort of road map to the rest of the chapter.

Review of the structure of HTTP transactions.

However, reading the spec is a tedious and often unpleasant experience, and readers of this book are assumed to be more casual writers of HTTP clients, so we've pared it down a bit to make HTTP more accessible for the spec-wary. HTTP is defined by the HTTP specification, distributed by the World Wide Web Consortium (W3C) at If you are writing commercial-quality HTTP applications, you should go directly to the spec, since it defines which features need to be supported for HTTP compliance. Chapter 2 was like the "Spanish for Travelers" phrasebook that you got for your trip to Madrid this chapter is the textbook for Spanish 101, required reading if you want course credit. But now it's time to teach you more about HTTP.

#Http client online software#

For the most part, all web software will use an exchange similar to the HTTP we showed you in Chapter 2, Demystifying the Browser. In the previous chapter, we went through a few examples of HTTP transactions and outlined the structure that all HTTP follows. This book is out of print, but it has been made available Web Client Programming with Perl Automating Tasks on the Web Web Client Programming with Perl: Chapter 3: Learning HTTP