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Web Client Programming with Perl-Chapter 5: The LWP Library- P1

Tham khảo tài liệu 'web client programming with perl-chapter 5: the lwp library- p1', công nghệ thông tin, quản trị web phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 5 The LWP Library- P1 As we showed in Chapter 1 the Web works over TCP IP in which the client and server establish a connection and then exchange necessary information over that connection. Chapters See Demystifying the Browser and See Learning HTTP concentrated on HTTP the protocol spoken between web clients and servers. Now we ll fill in the rest of the puzzle how your program establishes and manages the connection required for speaking HTTP. In writing web clients and servers in Perl there are two approaches. You can establish a connection manually using sockets and then use raw HTTP or you can use the library modules for WWW access in Perl otherwise known as LWP. LWP is a set of modules for Perl 5 that encapsulate common functions for a web client or server. Since LWP is much faster and cleaner than using sockets this book uses it for all the examples in Chapters See Example LWP Programs and . If LWP is not available on your platform see Chapter 4 which gives more detailed descriptions of the socket calls and examples of simple web programs using sockets. The LWP library is available at all CPAN archives. CPAN is a collection of Perl libraries and utilities freely available to all. There are many CPAN mirror sites you should use the one closest to you or just go to http www.perl.com CPAN to have one chosen for you at random. LWP was developed by a cast of thousands well maybe a dozen but its primary driving force is Gisle Aas. It is based on the libwww library developed for Perl 4 by Roy Fielding. Detailed discussion of each of the routines within LWP is beyond the scope of this book. However we ll show you how LWP can be used and give you a taste of it to get you started. This chapter is divided into three sections First we ll show you some very simple LWP examples to give you an idea of what it makes possible. Next we ll list most of the useful routines within the LWP library. At the end of the chapter we ll present some examples that glue together .