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 three backends: "DBM_Deep" for on-disk storage,
    "Memcached" for possibly multi-host 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.

