NAME

       LWP::Protocol - Base class for LWP protocols

SYNOPSIS

        package LWP::Protocol::foo;
        use base qw(LWP::Protocol);

DESCRIPTION

       This class is used as 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 initialized subclass appropriate for that access method. In other words, the "create"
       in LWP::Protocol 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.

METHODS

       The following methods and functions are provided:

   new
           my $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.

   create
           my $prot = LWP::Protocol::create($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.

   implementor
           my $class = LWP::Protocol::implementor($scheme, [$class])

       Get and/or set implementor class for a scheme.  Returns '' if the specified scheme is not
       supported.

   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.

   collect
           my $res = $prot->collect(undef, $response, $collector); # stored in $response
           my $res = $prot->collect($filename, $response, $collector);
           my $res = $prot->collect(sub { ... }, $response, $collector);

       Collect the content of a request, and process it appropriately into a scalar, file, or by
       calling a callback. If the first parameter is undefined, then the content is stored within
       the $response. If it's a simple scalar, then it's interpreted as a file name and the
       content is written to this file.  If it's a code reference, 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 string.

       The return value is the HTTP::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.

   collect_once
           $prot->collect_once($arg, $response, $content)

       Can be called when the whole response content is available as content. This will invoke
       "collect" in LWP::Protocol 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.