Exchanges

Before getting into the Consumers section there are two things you need to know about Exchanges.

Declaring a Exchange

Declaring an Exchange will either create a new one or, in case an exchange of that name was already declared, returns a reference to an existing one. If the Exchange already exists, but has different properties (type, internal, …) the action will fail.

import cats.effect.IO
import cats.implicits._
import dev.profunktor.fs2rabbit.interpreter.RabbitClient
import dev.profunktor.fs2rabbit.model._

val x1 = ExchangeName("x1")
val x2 = ExchangeName("x2")

def exchanges(R: RabbitClient[IO]) =
  R.createConnectionChannel.use { implicit channel =>
    R.declareExchange(x1, ExchangeType.Topic) *>
    R.declareExchange(x2, ExchangeType.FanOut)
  }

An Exchange can be declared passively, meaning that the Exchange is required to exist, whatever its properties.

import cats.effect.IO
import dev.profunktor.fs2rabbit.interpreter.RabbitClient
import dev.profunktor.fs2rabbit.model._

val x = ExchangeName("x")

def exchanges(R: RabbitClient[IO]) =
  R.createConnectionChannel.use { implicit channel =>
    R.declareExchangePassive(x)
  }

Binding Exchanges

Two exchanges can be bound together by providing a RoutingKey and some extra arguments with ExchangeBindingArgs.

def binding(R: RabbitClient[IO])(implicit channel: AMQPChannel) =
  R.bindExchange(x1, x2, RoutingKey("rk"), ExchangeBindingArgs(Map.empty))

Read more about Exchanges and ExchangeType here.