1LWP::Protocol(3)      User Contributed Perl Documentation     LWP::Protocol(3)
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NAME

6       LWP::Protocol - Base class for LWP protocols
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SYNOPSIS

9        package LWP::Protocol::foo;
10        require LWP::Protocol;
11        @ISA=qw(LWP::Protocol);
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DESCRIPTION

14       This class is used a the base class for all protocol implementations
15       supported by the LWP library.
16
17       When creating an instance of this class using
18       "LWP::Protocol::create($url)", and you get an initialised subclass
19       appropriate for that access method. In other words, the
20       LWP::Protocol::create() function calls the constructor for one of its
21       subclasses.
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23       All derived LWP::Protocol classes need to override the request() method
24       which is used to service a request. The overridden method can make use
25       of the collect() function to collect together chunks of data as it is
26       received.
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28       The following methods and functions are provided:
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30       $prot = LWP::Protocol->new()
31           The LWP::Protocol constructor is inherited by subclasses. As this
32           is a virtual base class this method should not be called directly.
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34       $prot = LWP::Protocol::create($scheme)
35           Create an object of the class implementing the protocol to handle
36           the given scheme. This is a function, not a method. It is more an
37           object factory than a constructor. This is the function user agents
38           should use to access protocols.
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40       $class = LWP::Protocol::implementor($scheme, [$class])
41           Get and/or set implementor class for a scheme.  Returns '' if the
42           specified scheme is not supported.
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44       $prot->request(...)
45            $response = $protocol->request($request, $proxy, undef);
46            $response = $protocol->request($request, $proxy, '/tmp/sss');
47            $response = $protocol->request($request, $proxy, \&callback, 1024);
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49           Dispatches a request over the protocol, and returns a response
50           object. This method needs to be overridden in subclasses.  Refer to
51           LWP::UserAgent for description of the arguments.
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53       $prot->collect($arg, $response, $collector)
54           Called to collect the content of a request, and process it
55           appropriately into a scalar, file, or by calling a callback.  If
56           $arg is undefined, then the content is stored within the $response.
57           If $arg is a simple scalar, then $arg is interpreted as a file name
58           and the content is written to this file.  If $arg is a reference to
59           a routine, then content is passed to this routine.
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61           The $collector is a routine that will be called and which is
62           responsible for returning pieces (as ref to scalar) of the content
63           to process.  The $collector signals EOF by returning a reference to
64           an empty sting.
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66           The return value from collect() is the $response object reference.
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68           Note: We will only use the callback or file argument if
69           $response->is_success().  This avoids sending content data for
70           redirects and authentication responses to the callback which would
71           be confusing.
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73       $prot->collect_once($arg, $response, $content)
74           Can be called when the whole response content is available as
75           $content.  This will invoke collect() with a collector callback
76           that returns a reference to $content the first time and an empty
77           string the next.
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SEE ALSO

80       Inspect the LWP/Protocol/file.pm and LWP/Protocol/http.pm files for
81       examples of usage.
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84       Copyright 1995-2001 Gisle Aas.
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86       This library is free software; you can redistribute it and/or modify it
87       under the same terms as Perl itself.
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91perl v5.16.3                      2012-01-14                  LWP::Protocol(3)
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