Hello RabbitMQ Go

Jan. 3, 2022

https://www.rabbitmq.com/tutorials/tutorial-one-go.html

Introduction

Producer: A program that sends messages.

Broker(Exchange+Binding+Queue): A queue is essentially a large message buffer and bound by the host’s memory & disk limits.

Consumer: A program that mostly waits to receive messages.

Installation

brew install rabbitmq

go get github.com/streadway/amqp

Sending(Producer)

// https://github.com/rabbitmq/rabbitmq-tutorials/blob/master/go/send.go
package main

import (
	"log"

	"github.com/streadway/amqp"
)

func failOnError(err error, msg string) {
	if err != nil {
		log.Panicf("%s: %s", msg, err)
	}
}

func main() {
	conn, err := amqp.Dial("amqp://guest:guest@localhost:5672/")
	failOnError(err, "Failed to connect to RabbitMQ")
	defer conn.Close()

	ch, err := conn.Channel()
	failOnError(err, "Failed to open a channel")
	defer ch.Close()

	q, err := ch.QueueDeclare(
		"hello", // name
		false,   // durable
		false,   // delete when unused
		false,   // exclusive
		false,   // no-wait
		nil,     // arguments
	)
	failOnError(err, "Failed to declare a queue")

	body := "Hello World!"
	err = ch.Publish(
		"",     // exchange
		q.Name, // routing key
		false,  // mandatory
		false,  // immediate
		amqp.Publishing{
			ContentType: "text/plain",
			Body:        []byte(body),
		})
	failOnError(err, "Failed to publish a message")
	log.Printf(" [x] Sent %s\n", body)
}

Receiving(Consumer)

// https://github.com/rabbitmq/rabbitmq-tutorials/blob/master/go/receive.go
package main

import (
	"log"

	"github.com/streadway/amqp"
)

func failOnError(err error, msg string) {
	if err != nil {
		log.Panicf("%s: %s", msg, err)
	}
}

func main() {
	conn, err := amqp.Dial("amqp://guest:guest@localhost:5672/")
	failOnError(err, "Failed to connect to RabbitMQ")
	defer conn.Close()

	ch, err := conn.Channel()
	failOnError(err, "Failed to open a channel")
	defer ch.Close()

	q, err := ch.QueueDeclare(
		"hello", // name
		false,   // durable
		false,   // delete when unused
		false,   // exclusive
		false,   // no-wait
		nil,     // arguments
	)
	failOnError(err, "Failed to declare a queue")

	msgs, err := ch.Consume(
		q.Name, // queue
		"",     // consumer
		true,   // auto-ack
		false,  // exclusive
		false,  // no-local
		false,  // no-wait
		nil,    // args
	)
	failOnError(err, "Failed to register a consumer")

	forever := make(chan bool)

	go func() {
		for d := range msgs {
			log.Printf("Received a message: %s", d.Body)
		}
	}()

	log.Printf(" [*] Waiting for messages. To exit press CTRL+C")
	<-forever
}

Queueing

# Runs at background
brew services start rabbitmq

watch '/usr/local/sbin/rabbitmqctl list_queues'

go run send.go

go run receive.go

brew services stop rabbitmq