Module: Iodine::PubSub

Defined in:

lib/iodine/pubsub.rb,
ext/iodine/iodine_pubsub.c

Overview

Note:

From –subscribe_pattern Wikipedia: publish–subscribe is a messaging pattern where senders of messages, called publishers, do not program the messages to be sent directly to specific receivers, called subscribers, but instead characterize published messages into classes without knowledge of which subscribers, if any, there may be. Similarly, subscribers express interest in one or more classes and only receive messages that are of interest, without knowledge of which publishers, if any, there are.

Iodine is equiped with an internal pub/sub service that allows improved resource management from a deployment perspective.

The common paradigm, which is implemented by pub/sub services like Redis, is for a “client” to “subscribe” to one or more “channels”. Messages are streamed to these “channels” by different “publishers” (the application / other clients) and are broadcasted to the “clients” through their “subscription”.

Iodine’s approach it to offload pub/sub resource costs from the pub/sub service (which is usually expensive to scale) onto the application layer.

For example, the default (‘nil`) pub/sub Engine implements an internal pub/sub service that manages subscriptions (clients and channels) throughout an Iodine process cluster without any need to connect to an external pub/sub service.

If Iodine was runninng with 8 processes and 16 threads per process, a publishing in process A will be delivered to subscribers in process B.

In addition, by inheriting the Engine class, it’s easy to create pub/sub engines that connect to this underlying pub/sub service. This means that Iodine will call the engine’s ‘subscribe` method only once per channel and once messages arrive, Iodine will distribute the messages to all the subscribed clients.

Defined Under Namespace

Classes: Engine, RedisEngine

Constant Summary

CLUSTER =

This is the (currently) default pub/sub engine. It will distribute messages to all subscribers in the process cluster.

engine_in_c

SINGLE_PROCESS =

This is a single process pub/sub engine. It will distribute messages to all subscribers sharing the same process.

engine_in_c