Multiple Consumers

Given two Consumers bound to queues with different RoutingKeys RKA and RKB and a single Publisher bound to a single RoutingKey named RKA we will be publishing messages to both queues but expecting to only consume messages published to the RKA. The second consumer bound to RKB will not receive any messages:

import cats.effect._
import dev.profunktor.fs2rabbit.config.declaration.DeclarationQueueConfig
import dev.profunktor.fs2rabbit.interpreter.RabbitClient
import dev.profunktor.fs2rabbit.model._
import fs2._

import scala.concurrent.ExecutionContext

implicit val cs = IO.contextShift(

val q1  = QueueName("q1")
val q2  = QueueName("q2")
val ex  = ExchangeName("testEX")
val rka = RoutingKey("RKA")
val rkb = RoutingKey("RKB")

val msg = Stream("Hey!").covary[IO]

def multipleConsumers(c1: Stream[IO, AmqpEnvelope[String]], c2: Stream[IO, AmqpEnvelope[String]], p: String => IO[Unit]) = {
    msg evalMap p,
    c1.through(_.evalMap(m => IO(println(s"Consumer #1 >> $m")))),
    c2.through(_.evalMap(m => IO(println(s"Consumer #2 >> $m"))))

def program(R: RabbitClient[IO]) =
  R.createConnectionChannel.use { implicit channel =>
    for {
      _  <- R.declareExchange(ex, ExchangeType.Topic)
      _  <- R.declareQueue(DeclarationQueueConfig.default(q1))
      _  <- R.declareQueue(DeclarationQueueConfig.default(q2))
      _  <- R.bindQueue(q1, ex, rka)
      _  <- R.bindQueue(q2, ex, rkb)
      c1 <- R.createAutoAckConsumer[String](q1)
      c2 <- R.createAutoAckConsumer[String](q2)
      p  <- R.createPublisher[String](ex, rka)
      _  <- multipleConsumers(c1, c2, p).compile.drain
    } yield ()

If we run this program, we should only see a message Consumer #1 >> Hey! meaning that only the consumer bound to the RKA routing key got the message.