Scan for rabbit exchanges from iOS - rabbitmq

Question

I'm trying to write something for my iOS app, using RMQClient that scans for existing exchanges on a rabbitmq server. I came up with this so far.
class AMQPExchangeScanner {
static func scan() {
let connection:RMQConnection = RMQConnection(uri: "amqp://user:user#abc.def.com:5672", delegate: RMQConnectionDelegateLogger())
connection.start()
for exchangeName in Foo.pastExchanges() {
let channel = connection.createChannel()
let exchange = channel.fanout(exchangeName, options: .passive)
"scan \(exchangeName) \(exchange)".print()
channel.close()
}
}
}
I'm not sure how to determine if the exchange actually exists though. The print() statement prints exchange objects. I get a whole bunch of output in the console. I had hoped that I would get back an optional so I could do something like
if let exchange... {
}
But that doesn't appear to be the case. How do I programmatically check if the exchange is real or not? Or get at those errors? Do I need my own connection delegate and have to parse a bunch of text?

Answer 1

The best way to scan for existing exchanges is using rabbitmq management HTTP API - it would be under /api/exchanges.
For a single exchange you could call the declare method, with passive parameter set accordingly (quoting from here):
for the declare method
This method creates an exchange if it does not already exist, and if
the exchange exists, verifies that it is of the correct and expected
class.
for the passive bit
If set, the server will reply with Declare-Ok if the exchange already
exists with the same name, and raise an error if not.
...
If not set and the exchange exists, the server MUST check that the existing exchange has the same values for type, durable, and arguments fields. The server MUST respond with Declare-Ok if the requested exchange matches these fields, and MUST raise a channel exception if not.