Section: User Contributed Perl Documentation (3pm)
use LWP::RobotUA; my $ua = LWP::RobotUA->new('my-robot/0.1', '[email protected]'); $ua->delay(10); # be very nice -- max one hit every ten minutes! ...
# Then just use it just like a normal LWP::UserAgent: my $response = $ua->get('http://whatever.int/...'); ...
This class implements a user agent that is suitable for robot applications. Robots should be nice to the servers they visit. They should consult the /robots.txt file to ensure that they are welcomed and they should not make requests too frequently.
But before you consider writing a robot, take a look at <URL:http://www.robotstxt.org/>.When you use an LWP::RobotUA object as your user agent, then you do not really have to think about these things yourself;
"robots.txt"files are automatically consulted and obeyed, the server isn't queried too rapidly, and so on. Just send requests as you do when you are using a normal LWP::UserAgent object (using
"$ua->request(...)", etc.), and this special agent will make sure you are nice.
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
"from"are mandatory. The options
"rules"initialize attributes private to the RobotUA. If
"rules"are not provided, then
"WWW::RobotRules"is instantiated providing an internal database of robots.txt.
"rules"as plain positional arguments.
- $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->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 a Retry-After header that indicates when it is OK to send another request to this server.:
- $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.:
- Returns a string that describes the state of the UA. Mainly useful for debugging.:
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.