LWP::Protocol

LWP::Protocol(3)     User Contributed Perl Documentation     LWP::Protocol(3)



NAME
       LWP::Protocol - Base class for LWP protocols

SYNOPSIS
	package LWP::Protocol::foo;
	require LWP::Protocol;
	@ISA=qw(LWP::Protocol);

DESCRIPTION
       This class is used a the base class for all protocol implementations
       supported by the LWP library.

       When creating an instance of this class using "LWP::Protocol::cre-
       ate($url)", and you get an initialised subclass appropriate for that
       access method. In other words, the LWP::Protocol::create() function
       calls the constructor for one of its subclasses.

       All derived LWP::Protocol classes need to override the request()
       method which is used to service a request. The overridden method can
       make use of the collect() function to collect together chunks of data
       as it is received.

       The following methods and functions are provided:

       $prot = LWP::Protocol->new()
	   The LWP::Protocol constructor is inherited by subclasses. As this
	   is a virtual base class this method should not be called directly.

       $prot = LWP::Protocol::create($scheme)
	   Create an object of the class implementing the protocol to handle
	   the given scheme. This is a function, not a method. It is more an
	   object factory than a constructor. This is the function user
	   agents should use to access protocols.

       $class = LWP::Protocol::implementor($scheme, [$class])
	   Get and/or set implementor class for a scheme.  Returns ’’ if the
	   specified scheme is not supported.

       $prot->request(...)
	    $response = $protocol->request($request, $proxy, undef);
	    $response = $protocol->request($request, $proxy, ’/tmp/sss’);
	    $response = $protocol->request($request, $proxy, \&callback, 1024);

	   Dispatches a request over the protocol, and returns a response
	   object. This method needs to be overridden in subclasses.  Refer
	   to LWP::UserAgent for description of the arguments.

       $prot->collect($arg, $response, $collector)
	   Called to collect the content of a request, and process it appro-
	   priately into a scalar, file, or by calling a callback.  If $arg
	   is undefined, then the content is stored within the $response.  If
	   $arg is a simple scalar, then $arg is interpreted as a file name
	   and the content is written to this file.  If $arg is a reference
	   to a routine, then content is passed to this routine.

	   The $collector is a routine that will be called and which is
	   responsible for returning pieces (as ref to scalar) of the content
	   to process.	The $collector signals EOF by returning a reference
	   to an empty sting.

	   The return value from collect() is the $response object reference.

	   Note: We will only use the callback or file argument if
	   $response->is_success().  This avoids sending content data for
	   redirects and authentication responses to the callback which would
	   be confusing.

       $prot->collect_once($arg, $response, $content)
	   Can be called when the whole response content is available as
	   $content.  This will invoke collect() with a collector callback
	   that returns a reference to $content the first time and an empty
	   string the next.

SEE ALSO
       Inspect the LWP/Protocol/file.pm and LWP/Protocol/http.pm files for
       examples of usage.

COPYRIGHT
       Copyright 1995-2001 Gisle Aas.

       This library is free software; you can redistribute it and/or modify
       it under the same terms as Perl itself.



perl v5.8.8			  2008-04-07		     LWP::Protocol(3)