Thanks Bonnie. I know that I should use web service (or .NET remoting), but with the learning curve and with the (too little) time I have to develop this application, it would add too much risk. My boss want something that run ASAP, even if that means taking longer to maintain after. Not my choice, but he's the one signing my check...

>I recommend XML and yes, it would be a string return type (DataSet.GetXML() will get you the proper string). Typically however, it would be the Web Service that would return the XML string, not the BO ... typically the BO would return a DataSet to the Web Service which would then return the XML string to the GUI.
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>I *do* question your decision to skip the Web Service for now and directly call the BO. Once you change to using a Web Service, then your GUI code will have to change to call a WebService instead of calling a BO. I think if you start out initially with all the pieces in place, it will be easier in the long run.