21
Option 2 – Model as First Class Concept
•Introduce an “Attribute” concept to wsdl:interface
–Similar to attribute in CORBA IDL
•Core idea:
–Elements of publicly available state are  modeled using XML Schema element
–State of a Web service instance is modeled “logically” as an XML instance document
–Define operations: get, set, query, [subscribe]
–Elements of state are modeled with the interface definition as attributes
–Use attributes to convey state and meta-data of the service
–Client proxy generators can still generate type-specific getters/setters (if they want)