#
# BioPerl module for FAST::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
=head1 NAME
FAST::Bio::WebAgent - A base class for Web (any protocol) access
=head1 SYNOPSIS
# This is a abstract superclass for bioperl modules accessing web
# resources - normally you do not instantiate it but one of its
# subclasess.
=head1 DESCRIPTION
This abstract superclass is a subclass of L<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 L<LWP::UserAgent>.
The interface is still evolving. For now, two public methods have been
copied from FAST::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 L<delay>.
=head1 SEE ALSO
L<LWP::UserAgent>,
L<FAST::Bio::DB::WebDBSeqI>,
=head1 FEEDBACK
=head2 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
=head2 Support
Please direct usage questions or support issues to the mailing list:
I<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.
=head2 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:
=head1 AUTHOR
Heikki Lehvaslaiho, heikki-at-bioperl-dot-org
=head1 COPYRIGHT
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.
=head1 DISCLAIMER
This software is provided "as is" without warranty of any kind.
=head1 APPENDIX
The rest of the documentation details each of the object
methods. Internal methods are usually preceded with a _
=cut
# Let the code begin...
use vars qw($LAST_INVOCATION_TIME);
use strict;
use base qw(LWP::UserAgent FAST::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!
}
# -----------------------------------------------------------------------------
=head2 url
Usage : $agent->url
Returns : URL to reach out to Net
Args : string
=cut
sub url {
my ($self,$value) = @_;
if( defined $value) {
$self->{'_url'} = $value;
}
return $self->{'_url'};
}
=head2 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().
=cut
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;
}
=head2 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.
=cut
sub delay_policy {
my $self = shift;
return 3;
}
=head2 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.
=cut
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__