I am developing an app right now which creates and stores a connection to a local XMPP server in the Application scope. The connection methods are stored in a cfc that makes sure the Application.XMPPConnection is connected and authorized each time it is used, and makes use of the connection to send live events to users. As far as I can tell, this is working fine. BUT it hasn't been tested under any kind of stress.
My question is: Will this set up cause problems later on? I only ask because I can't find evidence of other people using Application variables in this way. If I weren't using railo I would be using CF's event gateway instead to accomplish the same task.
Size itself isn't a problem. If you were to initialize one object per request, you'd burn a lot more memory. The problem is access.
If you have a large number of requests competing for the same object, you need to measure the access time for that object vs. instantiation. Keep in mind that, for data objects, more than one thread can read them. My understanding, though, is that when an object's function is called, it locks that object to other threads until the function returns.
Also, if the object maintains state, you need to consider what to do when multiple threads are getting/setting that data. Will you end up with race conditions?
You might consider handling this object in the session scope, so that it is only instantiated per user (who, likely, will only make one or two simultaneous requests).