COM port controller/driver

I need installable software that will control physical or virtual COM (RS232) port. Desired behavior and flow: 1. Software shouldn't block COM port, so other program will be able to use it. 2. Once external program sends communication to COM port, this communication should be buffered and exposed to third party software for analyzing. 3. Once analyzing id done, third party will notify COM controller if buffered message should be passed forward thru the port or not Use case example: We have POS software that is connected to receipt printer via COM port. Once receipt is available, POS sends it to predefined physical COM port, where printer should be connected. I want to be able to control what is sent to printer according certain logic. COM controller application should catch communication coming from POS to COM port, expose it to another process (by saving it to predefined folder for instance), and hold it until analyzing is done. Analyzer application will decide if receipt will be printed or not. if analyzer decides that receipt should be printed, it notifies COM controller and controller sends the communication thru the port to printer, otherwise, controller cleans the buffer and ready for next communication. COM controller should be compatible with all versions of Windows from XP and later.