sync-async

A small library for synchronizing asynchronous messaging.

With features such as publish and wait for a reply.

installation

A simple

npm -i sync-async

should do the trick

usage

The most simple use case is just publishing and listening on a topic

import {Topic} from "sync-async";
//fetch a topic to listen and publish on
let topic = Topic.getTopic<any>("test.topic");
//register a listener
topic.listen(v => console.log(`recieved message ${JSON.stringify(v)}`))
//publish a message on the topic
topic.publish({data: {a: 'b'}})

// outputs "recieved message {data: {a: 'b'}}"

sync-async allows you to also specify what message you want to return.

import {Topic} from "sync-async";
//fetch a topic to listen and publish on
let topic = Topic.getTopic<any>("test.topic");
//publish a message on the topic
topic.publishAndWait(
    { data: { a: "b" } }, //the data that we push to topic
    topic, //the topic that we listen for a reply on (same as the one we publish in this case)
    { b: "c" }, // The filter that we apply on the received message
    (v) => console.log(`got an object message in reply with a property named b, with value "c"`) // the callback function
);

Note that publishAndWait registeres a filtered listener that will only be activated once. Any future messages matching the filter will not trigger the callback

publishAndWait is also an async method so this is valid

await topic.publishAndWait(
    { data: { a: "b" } }, 
    topic, 
    { b: "c" }, 
    (v) => console.log(`hello`) 
);