 The invocation of the Web service operation was done using the SOAP UI test- ing tool. The following screenshot (Figures 12.47 and 12.48) shows the SOAP request and response for this invocation. Service Delivery Platforms getInstrumentList <soapenv:Invelope <SOAP-ENV: Rnvelope <BOAP-ENV:Invelope> Figure 12.47 SOAP request and response. On the left side of the image is the request and on the right side the response from the "VeLab" Web service. ExecuteCommand operation: As presented in the previous section, this Web ser- vice operation takes two parameters: InstrumentDescriptor: the instrument resource address descriptor formatted using VISA syntax. Command: the command to be executed on the specified instrument. This should have a standard VISA command. executeCommand http://192.168.67.64/axis/VeLabService <soapenv: Envelope mlns:vel=*http://velabservice/" <soapenv:Header/> <soapenv:Body> <vel:executeCommand> <vel:instrumentDescriptor>visa://192.168.67.101/GPIB0::22::NSTR</vel:instrumentDescriptor> <vel:command>*IDN?</vel:command> </vel:ezecuteCommand> </soapenv:Body> </soapenv:Envelope> Figure 12.48 SOAP response. Tele-Measurement Services for m-Learning Example of SOAP request: < soapenv : Envelope xmlns : soapenv = http://schemas.xmlsoap.org/soap/envelope/ xmlns vel ="http://velabservice/"> < soapenv:Header/: < soapenv:Body> <vel : executeCommand> <vel instrumentDescriptor visa://192.168.67.101/GPIB0: 22 : : INSTR </vel:instrumentDescriptor> <vel:command>*IDN?</ l : command> </vel:executeCommand /soapenv:Bod < /soapenv:Envelope > The response has the following fields: Instrumentdescriptor: the instrument where the command was executed InstrumentStatus: the status of the instrument after the command execution Result: the result returned by the instrument executionStatus: the status of the service execution executedCommand: the command that was executed errorMessage: if an error occurs during the service operation execution, a short message explaining the cause of the error will be returned. For example: "Error