# phpman > man > LWP::Protocol(3pm)

## NAME
    [LWP::Protocol](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AProtocol/markdown) - Base class for LWP protocols

## SYNOPSIS
     package [LWP::Protocol::foo](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AProtocol%3A%3Afoo/markdown);
     use parent qw([LWP::Protocol](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AProtocol/markdown));

## 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](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AProtocol%3A%3Acreate/markdown)($url)", and you get an
    initialized subclass appropriate for that access method. In other words, the "create" in
    [LWP::Protocol](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AProtocol/markdown) function calls the constructor for one of its subclasses.

    All derived "[LWP::Protocol](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AProtocol/markdown)" 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](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AProtocol/markdown)->new();

    The [LWP::Protocol](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AProtocol/markdown) constructor is inherited by subclasses. As this is a virtual base class this
    method should not be called directly.

  create
        my $prot = [LWP::Protocol::create](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AProtocol%3A%3Acreate/markdown)($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 $class = [LWP::Protocol::implementor](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AProtocol%3A%3Aimplementor/markdown)($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](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AUserAgent/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/HTTP%3A%3AResponse/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/LWP%3A%3AProtocol/markdown) 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.