@rxfx/bus

𝗥𝘅𝑓𝑥 bus

A typesafe, concurrency-controlled event bus. Part of the 𝗥𝘅𝑓𝑥 family of libraries.

If you're from React/Redux, NgRx, or generally want to use a reducer to keep track of state across events, have a look at @rxfx/service.

Minimal Bus Example

Explore this example for yourself on Repl.it

import { Bus } from '@rxfx/bus';
import { after } from '@rxfx/after';

const bus = new Bus<string>(); // or Redux FSA, etc.

/////// Listen and limit events (critera, handler) ////////
const listener = bus.listen(
  () => true, 
  (event) => after(1000, () => console.log(event))
);
bus.guard(e => !e.length, () => {
  throw new Error('non-empty strings!')}
);

/////// Then trigger them /////////////////////////////////
bus.trigger('Hello');
bus.trigger('World');

/////// Turn off listener (upon unmount, for example) /////
after(2000).then(() => listener.unsubscribe());

Overview

𝗥𝘅𝑓𝑥 is built upon RxJS, but with sugar for fewer imports, operators, and errors.

Mainly, a bus is a utility to implement the Publish-Subscribe pattern, aka "pub-sub".

Pub-sub can have the following benefits at dev-time and run-time:

• Decouple components statically from each other and frameworks
• Decouple the mapping of one-request-to-one-response allowing concurrency control, cancelation, and multi-part responses.

The first is accomplished by any pub-sub, or Redux.

The second is the speciality of an 𝗥𝘅𝑓𝑥 bus - which can invoke listeners in any concurrency mode of RxJS, without explicit imports for them.

Supported Concurrency Modes

Each of these RxJS-based concurrency modes can be achieved more easily by 𝗥𝘅𝑓𝑥, with fewer imports and easier switching.

Explore a live visualization of these and several custom modes, if you like.

To invoke them, just call bus.listenQueueing, for example. The default mode, Immediate, is invoked by bus.listen. For a custom mode, pass an operator that implements it as the final argument to bus.listen.

Examples

The following apps are built on bus events and listeners:

• Basic REPL - A basic tour of the type-safe bus methods.

• 7GUIs Circles - A drawing tool, challenge 6 in the 7GUIs suite.

• 7GUIs Cells - A reactive spreadsheet, challenge 7 in the 7GUIs suite.

For richer, stateful examples, see @rxfx/service.