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 $con-
           tent.  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 v5.8.6                       2007-07-19                  LWP::Protocol(3)