LWP::RobotUA(3pm) User Contributed Perl Documentation LWP::RobotUA(3pm)NAMELWP::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 = $ua->get('http://whatever.int/...');
...
DESCRIPTION
This class implements a user agent that is suitable for robot
applications. Robots should be nice to the servers they visit. They
should consult the /robots.txt file to ensure that they are welcomed
and they should not make requests too frequently.
But before you consider writing a robot, take a look at
<URL:http://www.robotstxt.org/>.
When you use an LWP::RobotUA object as your user agent, then you do not
really have to think about these things yourself; "robots.txt" files
are automatically consulted and obeyed, the server isn't queried too
rapidly, and so on. Just send requests as you do when you are using a
normal LWP::UserAgent object (using "$ua->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:
new
my $ua = LWP::RobotUA->new( %options )
my $ua = LWP::RobotUA->new( $agent, $from )
my $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.
delay
my $delay = $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);
use_sleep
my $bool = $ua->use_sleep;
$ua->use_sleep( $boolean );
Get/set a value indicating whether the UA should "sleep" in
LWP::RobotUA if requests arrive too fast, defined as "$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.
rules
my $rules = $ua->rules;
$ua->rules( $rules );
Set/get which WWW::RobotRules object to use.
no_visits
my $num = $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. :-(
host_wait
my $num = $ua->host_wait( $netloc )
Returns the number of seconds (from now) you must wait before you can
make a new request to this host.
as_string
my $string = $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.
perl v5.26.1 2017-12-26 LWP::RobotUA(3pm)
