After several hours of trying everything I could think of, I finally discovered what was causing the error from my previous post.

Unable to find the Flex adapter for destination ColdFusionGateway
 in the RMI registry on localhost:1099.

The Flex adapter may not be running or the destination may be incorrect.

The error occurred in C:\ColdFusion8\servers\cfusion\cfusion-ear\cfusion-war\webapps\test\scribble.cfm: line 24

22 : x.body = "hello world";
23 : x.destination = "ColdFusionGateway";
24 : sendGatewayMessage("test", x);
25 :
26 :</cfscript>

In the configuration file for the gateway, I had set the allowedIPs property to 127.0.0.1 so that it could only be testing from my machine. Well, for some reason, that was preventing the gateway from working. As soon as I commented out that property, it started to work.

# [Optional] The IP address or addresses of the Flex hosts that
# are allowed to connect and send messages to the Gateway.
# For multiple Flex servers, use a comma separated list: 10.60.1.1,10.60.1.2.
# If not specified, only this host is allowed.
#allowedIPs=127.0.0.1

I noticed comment “If not specified, only this host is allowed”, but it should read “If not specified, only this host is allowed, and you should NOT specify local host”.