lwp::protocol(3)
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::Proto
col::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 sub
classes. 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 proto
col to handle the given scheme. This is a function,
not a method. It is more an object factory than a con
structor. 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, un
- def);
$response = $protocol->request($request, $proxy, - '/tmp/sss');
$response = $protocol->request($request, $proxy, - callback, 1024);
- Dispactches a request over the protocol, and returns a
response object. This method needs to be overridden in
subclasses. Referer to LWP::UserAgent for description
of the arguments. - $prot->collect($arg, $response, $collector)
- Called to collect the content of a request, and pro
cess it appropriately into a scalar, file, or by call
ing a callback. If $arg is undefined, then the con
tent 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 reponsible 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 sendig con tent data for redirects and authentization 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.