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::create($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 appropriately 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 v5.12.1							    2009-07-07							  LWP::Protocol(3)