The Web Services Development Kit (WSDK) comprises a set of build-time tools and run-time components designed to support the development of web services and the interface to those services. WSDK provides a framework for the development of web services that isolates developers from the implementation details of the markup and transport layers, by separating the logical aspects of the service development from the physical aspects. A "call" generated by a client contains a batch of operations to be executed in the context of a single request/reply message exchange. A markup library translates logical structure to a specific markup language. Additional markup languages are supported by adding additional modules to the markup library.