Jason Foster created CAMEL-7031:
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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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