slimq

Slim Message Queue

Instead of using MQTT protocol directly, this module uses BSP protocol to encode and decode data in order to transfer arbitrary types of data.

Any other program intend to connect and transmit data along with this module must implement the encode and decode functions according to BSP documentation.

WARN: Unlike traditional MQTT protocol, this module also uses . instead of / to construct namespace of the topic, for a more universal experience when working with other protocols.

API

declare class SliMQ {
    protected config: mqtt.IClientOptions & { scope?: string; };
    protected topics: { [topic: string]: (data: any) => void };
    protected channel: mqtt.Client;
    constructor(config: mqtt.IClientOptions & { scope?: string; });
    connect(): Promise<this>;
    disconnect(): Promise<this>;
    publish<T = any, R = any>(topic: string, data: T, reply?: (data: R) => void): this;
    publish<T = any, R = any>(topic: string, data: T, options: {
        qos?: 0 | 1 | 2;
        retain?: boolean;
        dup?: boolean;
    }, reply?: (data: R) => void): this;
    subscribe<T = any, R = any>(topic: string, handler: (data: T, reply: (data: R) => void) => void): this;
    subscribe<T = any, R = any>(topic: string, options: {
        qos: 0 | 1 | 2
    }, handler: (data: T, reply: (data: R) => void) => void): this;
    unsubscribe(topic: string): this;
}

NOTE:

• mqtt package must be installed before using this module.
• If scope is provided in the config, it will be used as prefix to every topic that the current instance binds and sends.
• If calls subscribe on the same topic multiple times, the later ones will erase the former ones.

Example

Node.js

import SliMQ from "slimq";

const mq = new SliMQ({
    protocol: "mqtt",
    host: "test.mosquitto.org",
    port: 1883,
    scope: "test"
});

(async () => {
    await mq.connect();

    mq.subscribe<string>("greeting", (text) => {
        // `text` would be a string.
    }).subscribe<Buffer>("transmit-file", (file) => {
        // `file` would be a buffer.
    }).subscribe<string, string>("send-reply", (text, reply) => {
        // `text` would be a string, and `reply` must take a string argument.
        reply("You just sent: " + text);
    });

    mq.publish("greeting", "Hello, World!");
    mq.publish("transmit-file", fs.readFileSync("some-file.txt", "utf8"));
    mq.publish<string, string>("send-reply", "Hello, World!", (text) => {
        console.log(text); // You just sent: Hello, World!
    });
})();

Browser

In the browser, the mqtt package must be explicitly loaded to the global scope.

<script src="https://unpkg.com/mqtt@3.0.0/dist/mqtt.min.js"></script>
<script src="./bundle/slimq.js"></script>
<script>
const mq = new SliMQ({ /* config */ });

(async () => {
    await mq.connect();

    mq.subscribe<string>("greeting", (text) => {
        // `text` would be a string.
    }).subscribe<Uint8Array>("transmit-file", (file) => {
        // `file` would be a Uint8Array instance.
    }).subscribe<string, string>("send-reply", (text, reply) => {
        // `text` would be a string, and `reply` must take a string argument.
        reply("You just sent: " + text);
    });
})();
</script>