I\'m trying to setup my first RabbitMQ dead letter exchange, here are the steps I\'m using through the web admin interface:
Don't need to create FANOUT exchange if it is not compulsory.
You can create DIRECT exchange using the same routing key which you have used already for other exchange. And also don't need to create a new queue for the new exchange. You can use existing queues with new exchange. You just need to bind that new exchange with the queue.
Here is my receive.js file:
var amqp = require("amqplib/callback_api");
var crontab = require('node-crontab');
amqp.connect("amqp://localhost", function (err, conn) {
conn.createChannel(function (err, ch) {
var ex = 'direct_logs';
var ex2 = 'dead-letter-test';
var severity = 'enterprise-1-key';
//assert "direct" exchange
ch.assertExchange(ex, 'direct', { durable: true });
//assert "dead-letter-test" exchange
ch.assertExchange(ex2, 'direct', { durable: true });
//if acknowledgement is nack() then message will be stored in second exchange i.e. ex2="dead-letter-test"
ch.assertQueue('enterprise-11', { exclusive: false, deadLetterExchange: ex2 }, function (err, q) {
var n = 0;
console.log(' [*] Waiting for logs. To exit press CTRL+C');
console.log(q);
//Binding queue with "direct_logs" exchange
ch.bindQueue(q.queue, ex, severity);
//Binding the same queue with "dead-letter-test"
ch.bindQueue(q.queue, ex2, severity);
ch.consume(q.queue, function (msg) {
// consume messages via "dead-letter-exchange" exchange at every second.
if (msg.fields.exchange === ex2) {
crontab.scheduleJob("* * * * * *", function () {
console.log("Received by latest exchange %s", msg.fields.routingKey, msg.content.toString());
});
} else {
console.log("Received %s", msg.fields.routingKey, msg.content.toString());
}
if (n < 1) {
// this will executes first time only. Here I'm sending nack() so message will be stored in "deadLetterExchange"
ch.nack(msg, false, false);
n += 1;
} else {
ch.ack(msg)
n = 0
}
}, { noAck: false });
});
});
});