# LWP::Protocol - phpMan

## NAME
    [LWP::Protocol] - Base class for LWP protocols

## SYNOPSIS
     package [LWP::Protocol::foo];
     use parent 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()" method 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.