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This is an implementation of reactive streams, which, at the high level, is patterned off of the interfaces and protocols defined in http://reactive-streams.org.

It also draws a lot of inspiration from clojures Transducers, in that it attempts to decouple the functions doing the work from their plumbing. It does this with Strategies. These effect how a publisher/processor will consume and output data.

The high level API built on top of the interfaces (the customer facing portions) draw inspiration more from Elm than the java based Rx libraries.

The core types are as follows:

Producer<Strategy, Output> 

Producer is where most of the action happens. It generates data and supplies a datum at a time to its subscribers via the Subscriber::on_next method. If it has multiple subscribers, how it supplies each subscriber with data is up to the Strategy. It also limits its output using a pushback mechanism by being supplied a request amount by the subscriber (via its subscription). The hope is that a producer can be as simple as a proc, relying on the strategy and the subscription objects to do most of its heavy lifting, while the proc does only data transformation/generation.

OutputStrategy<Output>

There are many ways a producer might distribute data. When request limiting is present, there are a few options a strategy might take:

1. Keep all subscribers in-sync by broadcasting to all only when they all have remaining requests.
2. Eagerly send to any subscribers with available requests, discarding the messages to those without.
3. Round-Robin across subscribers with available requests.
4. Keep a queue for each subscriber which is currently without requests, in an attempt to keep all subscribers in sync.

InputStrategy<...>

An input Strategy is what copes with various types of input, Iterators, data structures, multiple subscriptions, etc. It can choose to execute one when it receives the other, or selects, or anything, really.

Subscriber<Input>

The subscriber subscribes to a Producer. Its only responsibility is to supply to the producer a reqeust number (via the subscription object) which acts as a backpressure mechanism.

Processor<Strategy, Input, Output> : Producer<Strategy, Output> + Subscriber<Input>

A processor is simply a Producer + a Subscriber. It is a link in the execution chain. Among its other responsibilities, it must pass down request backpressure values from its subscribers. It would also propagate errors downstream, and propagate unsubscribes upstream.

The MIT License (MIT)

Copyright (c) 2015 ReactiveX

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.