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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 v5.12.5                                     2011-04-09                                 LWP::Protocol(3)