The UPDD TUIO server program implements a TUIO server such that any application that is a TUIO client and receives TUIO touch data can be controlled with a UPDD driver supported touch-screen, thus expanding the number of multi-touch enabled applications that UPDD can support, the schematic being:

Touch hardware > UPDD driver > UPDD TUIO Server > TUIO client application > End user interaction

Currently the UPDD TUIO Server exists as a stand-alone application that is supplied for each operating system. Development history is shown here.

If using UPDD Commander (on Windows or MacOS) this has a built in TUIO server so it is unlikely that you will need to use the standalone TUIO Server in this case.