NAME

       IPC::PubSub - Interprocess Publish/Subscribe channels

SYNOPSIS

           # A new message bus with the DBM::Deep backend
           # (Other possible backends include Memcached and PlainHash)
           my $bus = IPC::PubSub->new(DBM_Deep => '/tmp/pubsub.db');

           # A channel is any arbitrary string
           my $channel = '#perl6';

           # Register a new publisher (you can publish to multiple channels)
           my $pub = $bus->new_publisher("#perl6", "#moose");

           # Publish a message (may be a complex object) to those channels
           $pub->msg("This is a message");

           # Register a new subscriber (you can subscribe to multiple channels)
           my $sub = $bus->new_subscriber("#moose");

           # Publish an object to channels
           $pub->msg("This is another message");

           # Set all subsequent messages from this publisher to expire in 30 seconds
           $pub->expiry(30);
           $pub->msg("This message will go away in 30 seconds");

           # Simple get: Returns the messages sent since the previous get,
           # but only for the first channel.
           my @msgs = $sub->get;

           # Simple get, with an explicit channel key (must be among the ones
           # it initially subscribed to)
           my @moose_msgs = $sub->get("#moose");

           # Complex get: Returns a hash reference from channels to array
           # references of [timestamp, message].
           my $hash_ref = $sub->get_all;

           # Changing the list of channels we subscribe to
           $sub->subscribe('some-other-channel');
           $sub->unsubscribe('some-other-channel');

           # Changing the list of channels we publish to
           $pub->publish('some-other-channel');
           $pub->unpublish('some-other-channel');

           # Listing and checking if we are in a channel
           my @sub_channels = $sub->channels;
           my @pub_channels = $pub->channels;
           print "Sub is in #moose" if $sub->channels->{'#moose'};
           print "Pub is in #moose" if $pub->channels->{'#moose'};

           # Raw cache manipulation APIs (not advised; use ->modify instead)
           $bus->lock('channel');
           $bus->unlock('channel');
           my @timed_msgs = $bus->fetch('key1', 'key2', 'key3');
           $bus->store('key', 'value', time, 30);

           # Atomic updating of cache content; $_ is stored back on the
           # end of the callback.
           my $rv = $bus->modify('key' => sub { delete $_->{foo} });

           # Shorthand for $bus->modify('key' => sub { $_ = 'val' });
           $bus->modify('key' => 'val');

           # Shorthand for $bus->modify('key' => sub { $_ });
           $bus->modify('key');

           # Disconnect the backend connection explicitly
           $bus->disconnect;

DESCRIPTION

       This module provides a simple API for publishing messages to channels and for subscribing
       to them.

       When a message is published on a channel, all subscribers currently in that channel will
       get it on their next "get" or "get_all" call.

       Currently, it offers four backends: "DBM_Deep" for on-disk storage, "Memcached" for
       possibly multi-host storage, "Jifty::DBI" for database-backed storage, and "PlainHash" for
       single-process storage.

       Please see the tests in t/ for this distribution, as well as "SYNOPSIS" above, for some
       usage examples; detailed documentation is not yet available.

SEE ALSO

       IPC::DirQueue, where the subscribers divide the published messages among themselves, so
       different subscribers never see the same message.

AUTHORS

       Audrey Tang <cpan@audreyt.org>

COPYRIGHT

       Copyright 2006, 2007 by Audrey Tang <cpan@audreyt.org>.

       This software is released under the MIT license cited below.

   The "MIT" License
       Permission is hereby granted, free of charge, to any person obtaining a copy of this
       software and associated documentation files (the "Software"), to deal in the Software
       without restriction, including without limitation the rights to use, copy, modify, merge,
       publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
       to whom the Software is furnished to do so, subject to the following conditions:

       The above copyright notice and this permission notice shall be included in all copies or
       substantial portions of the Software.

       THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
       PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
       FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
       OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
       DEALINGS IN THE SOFTWARE.