Emitter Golang SDK

This repository contains Go/Golang client for Emitter (see also on Emitter GitHub). Emitter is an open-source real-time communication service for connecting online devices. At its core, emitter.io is a distributed, scalable and fault-tolerant publish-subscribe messaging platform based on MQTT protocol and featuring message storage.

This library provides a nicer MQTT interface fine-tuned and extended with specific features provided by Emitter. The code uses the Eclipse Paho MQTT Go Client for handling all the network communication and MQTT protocol, and is released under the same license (EPL v1).

Usage

This library aims to be as simple and straighforward as possible. First thing you'll need to do is to import it.

import emitter "github.com/emitter-io/go/v2"

Then, you can use the functions exposed by Emitter type - they are simple methods such as Connect, Publish, Subscribe, Unsubscribe, GenerateKey, Presence, etc. See the example below.

func main() {


	// Create the client and connect to the broker
	c, _ := emitter.Connect("", func(_ *emitter.Client, msg emitter.Message) {
		fmt.Printf("[emitter] -> [B] received: '%s' topic: '%s'\n", msg.Payload(), msg.Topic())
	})

	// Set the presence handler
	c.OnPresence(func(_ *emitter.Client, ev emitter.PresenceEvent) {
		fmt.Printf("[emitter] -> [B] presence event: %d subscriber(s) at topic: '%s'\n", len(ev.Who), ev.Channel)
	})

	fmt.Println("[emitter] <- [B] querying own name")
	id := c.ID()
	fmt.Println("[emitter] -> [B] my name is " + id)

	// Subscribe to sdk-integration-test channel
	fmt.Println("[emitter] <- [B] subscribing to 'sdk-integration-test/'")
	c.Subscribe(key, "sdk-integration-test/", func(_ *emitter.Client, msg emitter.Message) {
		fmt.Printf("[emitter] -> [B] received on specific handler: '%s' topic: '%s'\n", msg.Payload(), msg.Topic())
	})

	// Ask for presence
	fmt.Println("[emitter] <- [B] asking for presence on 'sdk-integration-test/'")
	c.Presence(key, "sdk-integration-test/", true, false)

	// Publish to the channel
	fmt.Println("[emitter] <- [B] publishing to 'sdk-integration-test/'")
	c.Publish(key, "sdk-integration-test/", "hello")

	select {}  // wait forever without busy loop - Ctrl-c to stop
}

Installation and Build

This client, similarly to the Eclipse Paho client is designed to work with the standard Go tools, so installation is as easy as:

go get -u github.com/emitter-io/go/v2

For usage, please refer to the sample sub-folder in this repository which provides a sample application on how to use the API.

API Documentation

The full API documentation of exported members is available on godoc.org/github.com/emitter-io/go/v2.

License

Licensed with EPL 1.0, similarly to Eclipse Paho MQTT Client.