Summary

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

Package variables

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

Methods description

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

 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

 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

 Title   : sleep
 Usage   : $self->sleep
 Function: sleep for a number of seconds indicated by the delay policy
 Returns : none
 Args    : none

Methods code

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__

}

General documentation

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

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

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:

  http://bugzilla.open-bio.org/

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

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.

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

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