Bio::WebAgent - A base class for Web (any protocol) access

BioPerl documentation Contained in the BioPerl distribution.

Index

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NAME

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Bio::WebAgent - A base class for Web (any protocol) access

SYNOPSIS

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  # This is a abstract superclass for bioperl modules accessing web
  # resources - normally you do not instantiate it but one of its
  # subclasess.

DESCRIPTION

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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.

SEE ALSO

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LWP::UserAgent, Bio::DB::WebDBSeqI,

FEEDBACK

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Mailing Lists

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

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 Bugs

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/

AUTHOR

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Heikki Lehvaslaiho, heikki-at-bioperl-dot-org

COPYRIGHT

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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.

DISCLAIMER

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This software is provided "as is" without warranty of any kind.

APPENDIX

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The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _

url

 Usage   : $agent->url
 Returns : URL to reach out to Net
 Args    : string

delay

 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_policy

 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.

sleep

 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.

BioPerl documentation Contained in the BioPerl distribution. 
#
# BioPerl module for Bio::WebAgent
#
# Please direct questions and support issues to <bioperl-l@bioperl.org> 
#
# Cared for by Heikki Lehvaslaiho, heikki-at-bioperl-dot-org
# For copyright and disclaimer see below.
#

# POD documentation - main docs before the code



# Let the code begin...

package Bio::WebAgent;
use vars qw($LAST_INVOCATION_TIME);
use strict;

use base qw(LWP::UserAgent Bio::Root::Root);


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!

}


# -----------------------------------------------------------------------------


sub url { 
   my ($self,$value) = @_;
   if( defined $value) {
		$self->{'_url'} = $value;
   }
   return $self->{'_url'};
}



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;
}


sub delay_policy {
   my $self = shift;
   return 3;
}



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__