POE::Component::PubSub(3pm)				User Contributed Perl Documentation			       POE::Component::PubSub(3pm)

NAME

       POE::Component::PubSub - A generic publish/subscribe POE::Component that enables POE::Sessions to publish events to which other
       POE::Sessions may subscribe.

VERSION

       Version 0.04

SYNOPSIS

       # Instantiate the publish/subscriber with the alias "pub" POE::Component::PubSub->new('pub');

       # Publish an event called "FOO". +PUBLISH_OUTPUT is actually optional.  $_[KERNEL]->post('pub', 'publish', 'FOO', +PUBLISH_OUTPUT);

       # Elsewhere, subscribe to that event, giving it an event to call # when the published event is fired.  $_[KERNEL]->post('pub', 'subscribe',
       'FOO', 'FireThisEvent');

       # Fire off the published event $_[KERNEL]->post('pub', 'FOO');

       # Publish an 'input' event $_[KERNEL]->post('pub', 'publish', 'BAR', +PUBLISH_INPUT, 'MyInputEvent');

       # Tear down the whole thing $_[KERNEL]->post('pub', 'destroy');

EVENTS

       All public events do some sanity checking to make sure of a couple of things before allowing the events such as checking to make sure the
       posting session actually owns the event it is publishing, or that the event passed as the return event during subscription is owned by the
       sender. When one of those cases comes up, an error is carp'd, and the event returns without stopping execution.

       'publish'
	   This is the event to use to publish events. It accepts one argument, the event to publish. The published event may not already be
	   previously published. The event may be completely arbitrary and does not require the publisher to implement that event. Think of it as
	   a name for a mailing list.

	   You can also publish an 'input' or inverse event. This allows for arbitrary sessions to post to your event. In this case, you must
	   supply the optional published event type and the event to be called when the published event fires.

	   There are two types: PUBLISH_INPUT and PUBLISH_OUTPUT. PUBLISH_OUPUT is implied when no argument is supplied.

       'subscribe'
	   This is the event to use when subscribing to published events. It accepts two arguments: 1) the published event, and 2) the event name
	   of the subscriber to be called when the published event is fired. The event doesn't need to be published prior to subscription to
	   resolve chicken and egg problems in an async environment. But, the sender must own and implement the return event.

       'rescind'
	   Use this event to stop publication of an event. It accepts one argument, the published event. The event must be published, and
	   published by the sender of the rescind event. If the published event has any subscribers, a warning will be carp'd but execution will
	   continue.

       'cancel'
	   Cancel subscriptions to events with this event. It accepts one argment, the published event. The event must be published and the sender
	   must be subscribed to the event.

       '_default'
	   After an event is published, the publisher may arbitrarily fire that event to this component and the subscribers will be notified by
	   calling their respective return events with whatever arguments are passed by the publisher. The event must be published, owned by the
	   publisher, and have subscribers for the event to be propagated. If any of the subscribers no longer has a valid return event their
	   subscriptions will be cancelled and a warning will be carp'd.

       'listing'
	   To receive an array reference containing tuples of the event name, and the type of the events that are currently published within the
	   component, call this event. It accepts one argument, the return event to fire with the listing. The sender must own the return event.

       'destroy'
	   This event will simply destroy any of its current state and remove any and all aliases this session may have picked up. This should
	   free up the session for garbage collection.

CLASS METHODS

       POE::Component::PubSub->new($alias)
	   This is the constructor for the publish subscribe component. It instantiates it's own session using the provided $alias argument to set
	   its kernel alias.  If no alias is provided, the default alias is 'PUBLISH_SUBSCRIBE'.

DEBUGGING

       $POE::Component::PubSub::TRACE_AND_DEBUG
	   To enable debugging within the component at the POE::Session level and also with various warnings, set this variable to logical true
	   BEFORE calling new().

NOTES

       Right now this component is extremely simple, but thorough when it comes to checking the various requirements for publishing and
       subscribing. Currently, there is no mechanism to place meta-subscriptions to the events of the component itself. This feature is planned
       for the next release.

       Also, to do some of the checking on whether subscribers own the return events, some ideas were lifted from POE::API::Peek, and like that
       module, if there are changes to the POE core, they may break this module.

AUTHOR

       Nicholas R. Perez, "<nperez at cpan.org>"

BUGS

       Please report any bugs or feature requests to "bug-poe-component-pubsub at rt.cpan.org", or through the web interface at
       <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=POE-Component-PubSub>.  I will be notified, and then you'll automatically be notified of
       progress on your bug as I make changes.

SUPPORT

       You can find documentation for this module with the perldoc command.

	   perldoc POE::Component::PubSub

       You can also look for information at:

       o   AnnoCPAN: Annotated CPAN documentation

	   <http://annocpan.org/dist/POE-Component-PubSub>

       o   CPAN Ratings

	   <http://cpanratings.perl.org/d/POE-Component-PubSub>

       o   RT: CPAN's request tracker

	   <http://rt.cpan.org/NoAuth/Bugs.html?Dist=POE-Component-PubSub>

       o   Search CPAN

	   <http://search.cpan.org/dist/POE-Component-PubSub>

COPYRIGHT &; LICENSE
       Copyright 2008-2009 Nicholas R. Perez, all rights reserved.

       This program is released under the following license: gpl

perl v5.10.0							    2009-04-25					       POE::Component::PubSub(3pm)