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elmex |
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=head1 Network Programming with AnyEvent |
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This is a tutorial that will explain the usage of AnyEvent for |
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Network programming. |
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=head2 Introduction |
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AnyEvent is first of all just a framework for multiple event loops. It's a |
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thin abstraction layer above all kinds of event loops. It's main purpose is to |
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move the choice of the event loop (whether it should be Glib, Qt, EV or Event, |
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or even something else, see also L<AnyEvent>) from the module author to the |
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program author. |
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The problem was usually that modules like L<Net::IRC> came with their own |
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event loop, where the program author needed to start the event loop |
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of L<Net::IRC>. That usually meant that he couldn't integrate it easily with |
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a L<Gtk2> GUI for instance. |
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Another example is L<LWP>, it provides no event interface at all. It's a pure |
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blocking HTTP client library, which usually means that you either have to |
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start a thread or have to fork for a HTTP request, or use L<Coro::LWP>. |
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L<AnyEvent> now does B<not> force authors of modules, like L<Net::IRC>, to: |
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=over 4 |
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=item 1. Write their own event loop. |
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=item 2. Choose one fixed event loop. |
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=back |
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If the module author uses L<AnyEvent> for all his event needs (IO events, timers, |
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signals, ...) all other modules can just use his module and don't have to choose |
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an event loop or adapt to his event loop. The choice of the event loop is ultimately |
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made by the program author who uses all the modules and writes the main |
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program. And even there he doesn't have to choose, he can just ask L<AnyEvent> |
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to choose any available event loop for him. |
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Read more about this in the main documentation of the L<AnyEvent> module. |
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=head2 Network programming |
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However, AnyEvent is not just a simple abstraction anymore. It comes with |
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some very useful utility modules like L<AnyEvent::Handle>, L<AnyEvent::DNS> |
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and L<AnyEvent::Socket> that make your life as non-blocking network programmer |
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a lot easier. |
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Now an introduction into these three submodules: |
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=head3 L<AnyEvent::Handle> |
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This module handles non-blocking IO on filehandles in a event based |
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manner. It provides a wrapper object around your filehandle that provides |
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queueing and buffering of incoming and outgoing data for you. |
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More about this later. |
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=head3 L<AnyEvent::Socket> |
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This module provides you with functions that handle internet socket creation |
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and IP address magic. The two main functions are C<tcp_connect> and |
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C<tcp_server>. The former will connect a (streaming) socket to an internet host |
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for you and the later will make a server socket for you, to accept connections. |
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This module also comes with transparent IPv6 support, this means: If you |
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write your programs with this module, you will be IPv6 ready. |
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=head3 L<AnyEvent::DNS> |
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This module allows fully asynchronous DNS resolution, and is used for example |
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by L<AnyEvent::Socket> to resolve hostnames and service ports. |
