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Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :

ISBN : 978-2-7460-9712-4
EAN : 9782746097124
(Editions ENI)

GNU/Linux

CentOS 4.8

i386

LWP::RobotUA(3pm)


LWP::RobotUA

LWP::RobotUA

NAME
SYNOPSIS
DESCRIPTION
METHODS
SEE ALSO
COPYRIGHT

NAME

LWP::RobotUA − a class for well−behaved Web robots

SYNOPSIS

  use LWP::RobotUA;
  my $ua = LWP::RobotUA->new(’my-robot/0.1’, ’me@foo.com’);
  $ua->delay(10);  # be very nice -- max one hit every ten minutes!
  ...

  # Then just use it just like a normal LWP::UserAgent:
  my $response = $ua->get(’http://whatever.int/...’);
  ...

DESCRIPTION

This class implements a user agent that is suitable for robot applications. Robots should be nice to the servers they visit. They should consult the /robots.txt file to ensure that they are welcomed and they should not make requests too frequently.

But before you consider writing a robot, take a look at <URL:http://www.robotstxt.org/>.

When you use a LWP::RobotUA object as your user agent, then you do not really have to think about these things yourself; "robots.txt" files are automatically consulted and obeyed, the server isn’t queried too rapidly, and so on. Just send requests as you do when you are using a normal LWP::UserAgent object (using "$ua−>get(...)", "$ua−>head(...)", "$ua−>request(...)", etc.), and this special agent will make sure you are nice.

METHODS

The LWP::RobotUA is a sub-class of LWP::UserAgent and implements the same methods. In addition the following methods are provided:
$ua = LWP::RobotUA−>new( %options )
$ua = LWP::RobotUA−>new( $agent, $from )
$ua = LWP::RobotUA−>new( $agent, $from, $rules )

The LWP::UserAgent options "agent" and "from" are mandatory. The options "delay", "use_sleep" and "rules" initialize attributes private to the RobotUA. If "rules" are not provided, then "WWW::RobotRules" is instantiated providing an internal database of robots.txt.

It is also possible to just pass the value of "agent", "from" and optionally "rules" as plain positional arguments.

$ua−>delay
$ua−>delay( $minutes )

Get/set the minimum delay between requests to the same server, in minutes. The default is 1 minute. Note that this number doesn’t have to be an integer; for example, this sets the delay to 10 seconds:

    $ua->delay(10/60);

$ua−>use_sleep
$ua−>use_sleep( $boolean )

Get/set a value indicating whether the UA should sleep() if requests arrive too fast, defined as $ua−>delay minutes not passed since last request to the given server. The default is TRUE . If this value is FALSE then an internal SERVICE_UNAVAILABLE response will be generated. It will have an Retry-After header that indicates when it is OK to send another request to this server.

$ua−>rules
$ua−>rules( $rules )

Set/get which WWW::RobotRules object to use.

$ua−>no_visits( $netloc )

Returns the number of documents fetched from this server host. Yeah I know, this method should probably have been named num_visits() or something like that. :−(

$ua−>host_wait( $netloc )

Returns the number of seconds (from now) you must wait before you can make a new request to this host.

$ua−>as_string

Returns a string that describes the state of the UA . Mainly useful for debugging.

SEE ALSO

LWP::UserAgent, WWW::RobotRules

COPYRIGHT

Copyright 1996−2004 Gisle Aas.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.



LWP::RobotUA(3pm)