DPS - Distributed Pub/Sub

Multichannel distributed pub/sub messaging, with full duplication across several nodes.

Usage:

Channel creation

dps:new(<<"channel1">>),
dps:new(<<"channel2">>).

Publishing

dps:publish(<<"channel1">>, <<"Message1">>).

Subscribing for WebSockets

TS = 0,
dps:subscribe(<<"channel1">>, TS),
dps:subscribe(<<"channel2">>, TS),
dps:subscribe(<<"channel3">>, TS),
receive
  {dps_msg, Channel, LastTS, Messages} -> 
    reply({json, [{ts,LastTS},{messages,Messages}]})
end.

Subscribing for long-poll comet

multi_fetch will wait for first message from any requested channel. Can return immediately with many messages, if your TS is too old and some messages have arrived after it.

TS = list_to_integer(proplists:get_value("ts",Query, "0")),
{ok, LastTS, Messages} = dps:multi_fetch([<<"channel1">>,<<"channel2">>], TS, 30000),
reply({json, [{ts,LastTS}, {messages,Messages}]}).

TODO:

• Replace lists with a priority queue implementation
• Add tests (ideally - integration tests)
• Add more robust nodes discovering
• Add docs and specs
• Add channels closing support
• Compare to replicated redis pub/sub