How To Change To Previous Node Despite Persistence

We have an application that uses three servers in a Load Balancing Pool. And, we run with no persistence since the application requires that we switch Nodes with each request. I know that sounds strange, but it's the way the App Developers need it.

 

But, in certain situations, the application needs to send the request to the previously selected node. Specifically, when the application does inquiries (GETs) it needs to always change nodes, but when it does updates (POSTs) it needs to stay with the previously selected node.

 

I do have an iRule set up to select a specific node, but the tricky part is to figure out what the last selected node was. To do this, I set up a Cookie that would track the Node Selected. The challenge is that the client isn't a Web Browser, it's a Java application. I was hoping the application developer could program in to read the Cookie and send it back. So far, he is unwilling to do that.

 

Anybody have any ideas how I could do this? Is there some place in LTM where I could somehow retrieve the last session without relying on a Cookie or some other Header that required the Programmer to send it?