LWP::Protocol(3pm) | User Contributed Perl Documentation | LWP::Protocol(3pm) |
LWP::Protocol - Base class for LWP protocols
package LWP::Protocol::foo; use parent qw(LWP::Protocol);
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.
The following methods and functions are provided:
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.
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.
my $class = LWP::Protocol::implementor($scheme, [$class])
Get and/or set implementor class for a scheme. Returns '' if the specified scheme is not supported.
$response = $protocol->request($request, $proxy, undef); $response = $protocol->request($request, $proxy, '/tmp/sss'); $response = $protocol->request($request, $proxy, \&callback, 1024); $response = $protocol->request($request, $proxy, $fh);
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.
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. If it is a filehandle, or similar, such as a File::Temp object, content will be written to it.
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.
$prot->collect_once($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.
Inspect the LWP/Protocol/file.pm and LWP/Protocol/http.pm files for examples of usage.
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.
2023-03-01 | perl v5.36.0 |