writing an irule to log all traffic

Please allow me to take this question one step further. I have a need to log whenever someone uses the FTP APPEND command. My thought was that I do a TCP::collect in the client_accepted, then a switch statement in the client_data event. I cannot seem to get the order of the TCP::collect and TCP::release right as when I connect with the iRUle, I do not get anything past the connection. It is as if the iRule is waiting on a server response. I know that tcp::collect and release are slightly different than the http counterparts, but does anyone have a hint on how I can monitor basic data without affecting the flow of data between the client and server?