Although Microsoft and Mono both include XSD.exe with their distribution, both of them only generate concrete classes with XmlSerialization support. For small personal projects, concrete classes are appropriate, but for large complex applications, using JAXB style compilation is more appropriate. For those not familiar with JAXB, it generates an interface and concrete class. This means applications only reference the interface and do not use the concrete classes directly. It means the same class in a GUI can have different implementation than on the server.