lwp::protocol(3pm)
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::create($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
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 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
$content. 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.