lib::LWP::Protocol

Section: User Contributed Perl Documentation (3)
Updated: perl 5.004, patch 55
Index Return to Main Contents
 

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.  

SEE ALSO

Inspect the LWP/Protocol/file.pm and LWP/Protocol/http.pm files for examples of usage.  

METHODS AND FUNCTIONS

 

$prot = new HTTP::Protocol;

The LWP::Protocol constructor is inherited by subclasses. As this is a virtual base class this method should not be called directly.  

$prot = LWP::Protocol::create($url)

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);
Dispactches a request over the protocol, and returns a response object. This method needs to be overridden in subclasses. Referer to the LWP::UserAgent manpage for description of the arguments.  

$prot->timeout($seconds)

Get and set the timeout value in seconds  

$prot->use_alarm($yesno)

Indicates if the library is allowed to use the core alarm() function to implement timeouts.  

$prot->parse_head($yesno)

Should we initialize response headers from the <head> section of HTML documents.  

$prot->collect($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 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 content 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.

 

Index

NAME
SYNOPSIS
DESCRIPTION
SEE ALSO
METHODS AND FUNCTIONS
$prot = new HTTP::Protocol;
$prot = LWP::Protocol::create($url)
$class = LWP::Protocol::implementor($scheme, [$class])
$prot->request(...)
$prot->timeout($seconds)
$prot->use_alarm($yesno)
$prot->parse_head($yesno)
$prot->collect($arg, $response, $collector)
$prot->collect_once($arg, $response, $content)
This document was created by man2html, using the manual pages.
Time: 23:58:15 GMT, February 15, 2023