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:

       •   AnnoCPAN: Annotated CPAN documentation

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

       •   CPAN Ratings

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

       •   RT: CPAN's request tracker

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

       •   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 v5.34.0                                       2022-06-17                        POE::Component::PubSub(3pm)