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From "Jason Foster (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CAMEL-7031) RabbitMQ Producer not able to use the default exchange
Date Mon, 02 Dec 2013 21:54:35 GMT
Jason Foster created CAMEL-7031:
-----------------------------------

             Summary: RabbitMQ Producer not able to use the default exchange
                 Key: CAMEL-7031
                 URL: https://issues.apache.org/jira/browse/CAMEL-7031
             Project: Camel
          Issue Type: Bug
          Components: camel-rabbitmq
    Affects Versions: 2.12.2
            Reporter: Jason Foster


In RabbitMQ, the default exchange is a direct exchange with no name (empty string) and is
pre-declared by the broker. It has one special property that makes it very useful for simple
applications: every queue that is created is automatically bound to it with a routing key
which is the same as the queue name.  This is especially useful in RPC style messaging when
the producer specifies a REPLY_TO queue name that was created "exclusive"  Since RabbitMQ
binds that queue onto the default exchange, it makes RPC much simpler.

However, the camel rabbitmq producer throws an IllegalArgumentException if the exchange name
is empty, which prevents this simple RPC exchange.  The fix for this is simple, just don't
throw that IllegalArgumentException if the exchange name was set to empty string.

The same problem may exists with the Consumer as well.

This python script will send an rpc request (from RabbitMQ in Action)
import time, json, pika

creds_broker = pika.PlainCredentials("guest", "guest")
conn_params = pika.ConnectionParameters("localhost",
                                         virtual_host = "/",
                                         credentials = creds_broker)
conn_broker = pika.BlockingConnection(conn_params)
channel = conn_broker.channel()

msg = json.dumps({"client_name": "RPC Client 1.0",
                  "time" : time.time()})
result = channel.queue_declare(exclusive=True, auto_delete=True)
msg_props = pika.BasicProperties()
msg_props.reply_to = result.method.queue
msg_props.content_type = "application/json"
msg_props.correlation_id = "1"
msg_props.delivery_mode = 2

channel.basic_publish(body=msg,
                      exchange="rpc",
                      properties=msg_props,
                      routing_key="ping")

print "Sent 'Ping' RPC call.  Waiting for reply..."

def reply_callback(channel, method, header, body):
     """Receives RPC server replies."""
     print "RPC Reply --- " + body
     channel.stop_consuming()

channel.basic_consume(reply_callback,
                      queue=result.method.queue,
                      consumer_tag=result.method.queue)

channel.start_consuming()


This route would be what I would want to do when consuming from Rabbit the rpc call and sending
back a response:

        from("rabbitmq://192.168.213.130/rpc?queue=ping&routingKey=ping&durable=True&autoDelete=False&autoAck=False&username=guest&password=guest")
            .log("Incoming Headers: ${headers}")
            .setHeader("rabbitmq.ROUTING_KEY", header("rabbitmq.REPLY_TO"))
            .removeHeader("rabbitmq.REPLY_TO")
            .removeHeader("rabbitmq.EXCHANGE_NAME")
            .setBody(simple("Pong!"))
            .to("rabbitmq://192.168.213.130/?username=guest&password=guest");


If I remove the illegalargumentexception, the code works as expected.



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