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

       LWP::Protocol - Base class for LWP protocols

        package LWP::Protocol::foo;
        require LWP::Protocol;

       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 sub-
       class appropriate for that access method. In other words, the LWP::Protocol::create() function calls the con-
       structor 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.

            $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 ref-
           erence 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 con-
           tent 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.

       Inspect the LWP/Protocol/ and LWP/Protocol/ files for examples of usage.

       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                       2008-12-05                  LWP::Protocol(3)