Bio WebAgent
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Summary
Bio::WebAgent - A base class for Web (any protocol) access
Package variables
No package variables defined.
Inherit
Bio::Root::Root LWP::UserAgent
Synopsis
  # This is a abstract superclass for bioperl modules accessing web
# resources - normally you do not instantiate it but one of its
# subclasess.
Description
This abstract superclass is a subclass of LWP::UserAgent which
allows protocol independent access of remote locations over
the Net.
It takes care of error handling, proxies and various net protocols.
BioPerl classes accessing the net should inherit from it. For details,
see LWP::UserAgent.
The interface is still evolving. For now, two public methods have been
copied from Bio::DB::WebDBSeqI: delay() and delay_policy. These are
used to prevent overwhelming the server by rapidly repeated . Ideally
there should be a common abstract superclass with these. See delay.
Methods
new
No description
Code
urlDescriptionCode
delayDescriptionCode
delay_policyDescriptionCode
sleepDescriptionCode
Methods description
urlcode    nextTop
 Usage   : $agent->url
Returns : URL to reach out to Net
Args : string
delaycodeprevnextTop
 Title   : delay
Usage : $secs = $self->delay([$secs])
Function: get/set number of seconds to delay between fetches
Returns : number of seconds to delay
Args : new value
NOTE: the default is to use the value specified by delay_policy().
This can be overridden by calling this method, or by passing the
-delay argument to new().
delay_policycodeprevnextTop
 Title   : delay_policy
Usage : $secs = $self->delay_policy
Function: return number of seconds to delay between calls to remote db
Returns : number of seconds to delay
Args : none
NOTE: The default delay policy is 3s. Override in subclasses to
implement other delays. The timer has only second resolution, so the delay
will actually be +/- 1s.
sleepcodeprevnextTop
 Title   : sleep
Usage : $self->sleep
Function: sleep for a number of seconds indicated by the delay policy
Returns : none
Args : none
NOTE: This method keeps track of the last time it was called and only
imposes a sleep if it was called more recently than the delay_policy()
allows.
Methods code
newdescriptionprevnextTop
sub new {
	my $class = shift;

        # We make env_proxy the default here, but it can be 
# over-ridden by $self->env_proxy later,
# or by new(env_proxy=>0) at constructor time
my $self = $class->SUPER::new(env_proxy => 1); while( @_ ) { my $key = shift; $key =~ s/^-//; my $value = shift; $self->can($key) || next; $self->$key($value); } return $self; # success - we hope!
} # -----------------------------------------------------------------------------
}
urldescriptionprevnextTop
sub url {
    my ($self,$value) = @_;
   if( defined $value) {
		$self->{'_url'} = $value;
   }
   return $self->{'_url'};
}
delaydescriptionprevnextTop
sub delay {
   my ($self, $value) = @_;
   if ($value) {
       $self->throw("Need a positive integer, not [$value]")
           unless $value >= 0;
       $self->{'_delay'} = int $value;
   }
   return $self->{'_delay'} || $self->delay_policy;
}
delay_policydescriptionprevnextTop
sub delay_policy {
   my $self = shift;
   return 3;
}
sleepdescriptionprevnextTop
sub sleep {
   my $self = shift;
   $LAST_INVOCATION_TIME ||=  0;
   if (time - $LAST_INVOCATION_TIME < $self->delay) {
      my $delay = $self->delay - (time - $LAST_INVOCATION_TIME);
      $self->debug("sleeping for $delay seconds\n");
      sleep $delay;
   }
   $LAST_INVOCATION_TIME = time;
}

1;

__END__
}
General documentation
SEE ALSOTop
LWP::UserAgent,
Bio::DB::WebDBSeqI,
FEEDBACKTop
Mailing ListsTop
User feedback is an integral part of the evolution of this and other
Bioperl modules. Send your comments and suggestions preferably to
the Bioperl mailing list. Your participation is much appreciated.
  bioperl-l@bioperl.org                  - General discussion
http://bioperl.org/wiki/Mailing_lists - About the mailing lists
Support Top
Please direct usage questions or support issues to the mailing list:
bioperl-l@bioperl.org
rather than to the module maintainer directly. Many experienced and
reponsive experts will be able look at the problem and quickly
address it. Please include a thorough description of the problem
with code and data examples if at all possible.
Reporting BugsTop
Report bugs to the Bioperl bug tracking system to help us keep track
of the bugs and their resolution. Bug reports can be submitted via the
web:
  https://redmine.open-bio.org/projects/bioperl/
AUTHORTop
Heikki Lehvaslaiho, heikki-at-bioperl-dot-org
COPYRIGHTTop
Copyright (c) 2003, Heikki Lehvaslaiho and EMBL-EBI.
All Rights Reserved.
This module is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
DISCLAIMERTop
This software is provided "as is" without warranty of any kind.
APPENDIXTop
The rest of the documentation details each of the object
methods. Internal methods are usually preceded with a _