External Interfaces

Programming with Web Services

Because the Internet is inherently unpredictable, make sure that you take proper precautions in programming with Web services. One way to minimize the risk is to use common program control and error-handling routines.

Common programming techniques that you might use include

• Try - Catch statements can catch errors that result from method calls as well as creating the MATLAB class from the WSDL. The following example shows a method call in a try - catch statement:

• try
      t = getTemp(TemperatureService, '01760');
  catch
      t = Nan;
      disp(lasterr);
  end
  

• If statements can check that expressions or statements are true or false. The following example uses an if statement to cache the WSDL locally:

• wsdlUrl = 
  'http://www.xmethods.net/sd/2001/TemperatureService.wsdl';
  wsdlFile = 'TemperatureService.wsdl';
  if ~(exist(wsdlFile,'file') == 2)
      urlwrite(wsdlUrl,wsdlFile);
  end
  

• Error functions can be used to throw specific errors. The following example shows an error function used in an try - catch statement:

• try
      t = getTemp(TemperatureService, '01760');
  catch
      error('Could not return temperature');
  end
  

For more information about program control and error-handling statements, see the MATLAB Programming documentation.

Understanding Web Service Limitations

Simple M-File Example

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