go_messages.org

Go Messaging System

Nats

Message Echo System

Intro

Nats Server는 IoT 메시징 및 마이크로 서비스 아키텍처를 위한 간단하고 고성능의 오픈소스 메시징 시스템 입니다. go로 작성되어 있으며 Python, Java, Ruby, Node.js 등으로 작성된 클라이언트가 있습니다.

NATS Design Goals

The core principles underlying NATS are performance, scalability, and ease-of-use. Based on these principles, NATS is designed around the following core features:

• Highly performant (fast)
• Always on and available (dial tone)
• Extremely lightweight (small footprint)
• Support for multiple qualities of service (including guaranteed “at-least-once” delivery with NATS Streaming)
• Support for various messaging models and use cases (flexible)

Pub Code

	var urls = flag.String("s", nats.DefaultURL, "The nats server URLs (separated by comma)")

	log.SetFlags(0)
	flag.Usage = usage
	flag.Parse()

	args := flag.Args()
	if len(args) < 2 {
		usage()
	}

	nc, err := nats.Connect(*urls)
	if err != nil {
		log.Fatal(err)
	}
	defer nc.Close()

	subj, msg := args[0], []byte(args[1])
	
	for  {
		nc.Publish(subj, msg)
		nc.Flush()
	}

	if err := nc.LastError(); err != nil {
		log.Fatal(err)
	} else {
		log.Printf("Published [%s] : '%s'\n", subj, msg)
	}

Sub Code

	var urls = flag.String("s", nats.DefaultURL, "The nats server URLs (separated by comma)")
	var showTime = flag.Bool("t", false, "Display timestamps")

	log.SetFlags(0)
	flag.Usage = usage
	flag.Parse()

	args := flag.Args()
	if len(args) < 1 {
		usage()
	}

	nc, err := nats.Connect(*urls)
	if err != nil {
		log.Fatalf("Can't connect: %v\n", err)
	}

	subj, i := args[0], 0

	nc.Subscribe(subj, func(msg *nats.Msg) {
		i += 1
		printMsg(msg, i)
	})
	nc.Flush()

	if err := nc.LastError(); err != nil {
		log.Fatal(err)
	}

	log.Printf("Listening on [%s]\n", subj)
	if *showTime {
		log.SetFlags(log.LstdFlags)
	}