lwp::robotua.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

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.\" ========================================================================
.\"
.IX Title "LWP::RobotUA 3"
.TH LWP::RobotUA 3 "2004-04-06" "perl v5.10.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
LWP::RobotUA \- a class for well\-behaved Web robots
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 4
\&  use LWP::RobotUA;
\&  my $ua = LWP::RobotUA\->new(\*(Aqmy\-robot/0.1\*(Aq, \*([e-mail]\*(Aq);
\&  $ua\->delay(10);  # be very nice \-\- max one hit every ten minutes!
\&  ...
\&
\&  # Then just use it just like a normal LWP::UserAgent:
\&  my $response = $ua\->get(\*(Aqhttp://whatever.int/...\*(Aq);
\&  ...
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This class implements a user agent that is suitable for robot
applications.  Robots should be nice to the servers they visit.  They
should consult the \fI/robots.txt\fR file to ensure that they are welcomed
and they should not make requests too frequently.
.PP
But before you consider writing a robot, take a look at
<URL:http://www.robotstxt.org/>.
.PP
When you use a \fILWP::RobotUA\fR object as your user agent, then you do not
really have to think about these things yourself; \f(CW\*(C`robots.txt\*(C'\fR files
are automatically consulted and obeyed, the server isn't queried
too rapidly, and so on.  Just send requests
as you do when you are using a normal \fILWP::UserAgent\fR
object (using \f(CW\*(C`$ua\->get(...)\*(C'\fR, \f(CW\*(C`$ua\->head(...)\*(C'\fR,
\&\f(CW\*(C`$ua\->request(...)\*(C'\fR, etc.), and this
special agent will make sure you are nice.
.SH "METHODS"
.IX Header "METHODS"
The LWP::RobotUA is a sub-class of LWP::UserAgent and implements the
same methods. In addition the following methods are provided:
.ie n .IP "$ua\fR = LWP::RobotUA\->new( \f(CW%options )" 4
.el .IP "\f(CW$ua\fR = LWP::RobotUA\->new( \f(CW%options\fR )" 4
.IX Item "$ua = LWP::RobotUA->new( %options )"
.PD 0
.ie n .IP "$ua\fR = LWP::RobotUA\->new( \f(CW$agent\fR, \f(CW$from )" 4
.el .IP "\f(CW$ua\fR = LWP::RobotUA\->new( \f(CW$agent\fR, \f(CW$from\fR )" 4
.IX Item "$ua = LWP::RobotUA->new( $agent, $from )"
.ie n .IP "$ua\fR = LWP::RobotUA\->new( \f(CW$agent\fR, \f(CW$from\fR, \f(CW$rules )" 4
.el .IP "\f(CW$ua\fR = LWP::RobotUA\->new( \f(CW$agent\fR, \f(CW$from\fR, \f(CW$rules\fR )" 4
.IX Item "$ua = LWP::RobotUA->new( $agent, $from, $rules )"
.PD
The LWP::UserAgent options \f(CW\*(C`agent\*(C'\fR and \f(CW\*(C`from\*(C'\fR are mandatory.  The
options \f(CW\*(C`delay\*(C'\fR, \f(CW\*(C`use_sleep\*(C'\fR and \f(CW\*(C`rules\*(C'\fR initialize attributes
private to the RobotUA.  If \f(CW\*(C`rules\*(C'\fR are not provided, then
\&\f(CW\*(C`WWW::RobotRules\*(C'\fR is instantiated providing an internal database of
\&\fIrobots.txt\fR.
.Sp
It is also possible to just pass the value of \f(CW\*(C`agent\*(C'\fR, \f(CW\*(C`from\*(C'\fR and
optionally \f(CW\*(C`rules\*(C'\fR as plain positional arguments.
.ie n .IP "$ua\->delay" 4
.el .IP "\f(CW$ua\fR\->delay" 4
.IX Item "$ua->delay"
.PD 0
.ie n .IP "$ua\fR\->delay( \f(CW$minutes )" 4
.el .IP "\f(CW$ua\fR\->delay( \f(CW$minutes\fR )" 4
.IX Item "$ua->delay( $minutes )"
.PD
Get/set the minimum delay between requests to the same server, in
\&\fIminutes\fR.  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:
.Sp
.Vb 1
\&    $ua\->delay(10/60);
.Ve
.ie n .IP "$ua\->use_sleep" 4
.el .IP "\f(CW$ua\fR\->use_sleep" 4
.IX Item "$ua->use_sleep"
.PD 0
.ie n .IP "$ua\fR\->use_sleep( \f(CW$boolean )" 4
.el .IP "\f(CW$ua\fR\->use_sleep( \f(CW$boolean\fR )" 4
.IX Item "$ua->use_sleep( $boolean )"
.PD
Get/set a value indicating whether the \s-1UA\s0 should \fIsleep()\fR if requests
arrive too fast, defined as \f(CW$ua\fR\->delay minutes not passed since
last request to the given server.  The default is \s-1TRUE\s0.  If this value is
\&\s-1FALSE\s0 then an internal \s-1SERVICE_UNAVAILABLE\s0 response will be generated.
It will have an Retry-After header that indicates when it is \s-1OK\s0 to
send another request to this server.
.ie n .IP "$ua\->rules" 4
.el .IP "\f(CW$ua\fR\->rules" 4
.IX Item "$ua->rules"
.PD 0
.ie n .IP "$ua\fR\->rules( \f(CW$rules )" 4
.el .IP "\f(CW$ua\fR\->rules( \f(CW$rules\fR )" 4
.IX Item "$ua->rules( $rules )"
.PD
Set/get which \fIWWW::RobotRules\fR object to use.
.ie n .IP "$ua\fR\->no_visits( \f(CW$netloc )" 4
.el .IP "\f(CW$ua\fR\->no_visits( \f(CW$netloc\fR )" 4
.IX Item "$ua->no_visits( $netloc )"
Returns the number of documents fetched from this server host. Yeah I
know, this method should probably have been named \fInum_visits()\fR or
something like that. :\-(
.ie n .IP "$ua\fR\->host_wait( \f(CW$netloc )" 4
.el .IP "\f(CW$ua\fR\->host_wait( \f(CW$netloc\fR )" 4
.IX Item "$ua->host_wait( $netloc )"
Returns the number of \fIseconds\fR (from now) you must wait before you can
make a new request to this host.
.ie n .IP "$ua\->as_string" 4
.el .IP "\f(CW$ua\fR\->as_string" 4
.IX Item "$ua->as_string"
Returns a string that describes the state of the \s-1UA\s0.
Mainly useful for debugging.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
LWP::UserAgent, WWW::RobotRules
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 1996\-2004 Gisle Aas.
.PP
This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.