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1. What is he difference between Logical Type and Physical Type. From the comments in DataType.java, logical type is used by the assembly, physical type is used by the runtime, and for Tuscany Java the physical type is always a Java Type.
   The logical type represents the data type the user thinks is flowing across a wire. This could be a Java type, a XML type, a CORBA type, whatever depending on the /logical/ service contract defined in the assembly.
   The physical type is the actual representation of that type that is flowed by the runtime. In the Java runtime this will always be a Java type (i.e. some subclass of Object). In some cases it will be the same as the logical type - e.g. when a Java component calls another Java component over a local wire using a Java interface then both logical and physical types will be the same. In many cases though they will be different - for example, if the service contract was WSDL then the logical type would be the XML type used by the WSDL.
   Within the runtime the same logical type may have different physical forms. For example, the same XML document could be represented physically as a DOM, a StAX stream, an SDO, a JAXB object, or an AXIOM stream. The framework supports conversion between these different physical forms.