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Transient Queues

Let's update our code to automatically create and delete transient queues, rather than doing it manually. We'll create the queues that the client will use to receive the "pause" messages from the server.

Durable and Transient Queue Types

Durable queues survive a RabbitMQ server restart, while transient queues do not. We can also set the auto-delete and exclusive properties of our queues:

Exclusive: The queue can only be used by the connection that created it.
Auto-delete: The queue will be automatically deleted when its last connection is closed.

For simplicity of our game, we'll make our transient and durable queues always have the same properties:

"Durable" queues in our system will always be non-exclusive and non-auto-delete.
"Transient" queues will always be exclusive and auto-delete.

Assignment

Update the cmd/client package to connect to Rabbit, similar to the cmd/server package.
Use the ClientWelcome() function in internal/gamelogic to prompt the user for a username.
Declare and bind a transient queue by creating and using a new function in the internal/pubsub package. I called mine DeclareAndBind with this signature:

func DeclareAndBind(
	conn *amqp.Connection,
	exchange,
	queueName,
	key string,
	queueType SimpleQueueType, // SimpleQueueType is an "enum" type I made to represent "durable" or "transient"
) (*amqp.Channel, amqp.Queue, error)

In DeclareAndBind:
1. Create a new .Channel() on the connection.
2. Declare a new queue using .QueueDeclare():
  1. The durable parameter should only be true if queueType is durable.
  2. The autoDelete parameter should be true if queueType is transient.
  3. The exclusive parameter should be true if queueType is transient.
  4. The noWait parameter should be false.
  5. The args parameter should be nil.
3. Bind the queue to the exchange using .QueueBind().
4. Return the channel and queue.
Back in the cmd/client package, use these parameters to call DeclareAndBind:
1. exchange: peril_direct (this is a constant in the internal/routing package)
2. queueName: pause.username where username is the user's input. The pause section of the name is the routing key constant in the internal/routing package and is joined by a ..
3. routingKey: pause (this is a constant in the internal/routing package)
4. queueType: transient
After declaring and binding the queue, the client should wait for a Ctrl+C signal to exit.
Run the client! Enter suntzu (all lowercase) as the username.
It will print out some nonsense about possible commands, but you can ignore that. You can't run them yet because we haven't implemented them.
Check the RabbitMQ management UI to see if the queue was created and bound to the exchange.
Close the client. If all goes well, the queue should automatically be deleted after a few seconds.
Run the client as suntzu again, making sure the queue is recreated.

Run and submit the CLI tests with the client still open.