on function receives two main parameters, namely the MAC address of the mobile phone to which one wants to connect and the channel number (which in the case of the Bluetooth dial-up service is 0). The subVI then sends a sequence of standard AT commands for initiating and performing a GPRS transfer. These commands are sent over Bluetooth by calling LabVIEW's Bluetooth Write.VI function. They are as follows: AT + CGATT = 1-attaches the mobile unit to the GPRS network AT + CGDCONT = 1, "IP," "internet"-defines a mobile operator specific PDP context AT + CGACT = 1,1-activates that context ATD *99***1#connects to the GPRS network The present implementation proved the possibility to use powerful instrumen- tation hardware and software (NI CF6004 and NI LabVIEW) in a much minia- turized format (for PDA) for mobile tele-monitoring. 0[0..1] 00:14:A7:00:47:8e channel (0) U16 I AT+CGATT=1 AT+CGDCONT=1, "IP", "internet" AT+CGACT=1,1 Figure 12.32 SubVI for Bluetooth transmission using AT Commands. Service Delivery Platforms 12.3.2 VISA Approach to Instrumentation Accessed via Web Services Rationale: This section will focus on presenting an approach that allows remote access to a VISA compliant instrument by using Web services [41]. Web services provide a standard means of interoperating between different soft- ware applications, running on a variety of platforms and/or frameworks. Since they are based on open standards such as HTTP- and XML-based protocols including SOAP and WSDL, Web services are hardware, programming language, and oper- ating system independent. By using Web services we have the possibility to decouple clients from the under- laying hardware and platform and also in the same time to provide a standardized way of accessing the hardware resources, namely the VISA instrumentation. The client application is completely decoupled from the instrumentation hardware, and has no dependency on drivers or any other hardware access routines. With this approach we eliminate the need to install and configure runtime envi-