63. A computer-accessible storage medium comprising program instructions, wherein the program instructions are configured to implement: a Web services stack on a system configured to communicate with other systems using either a binary encoding protocol or a markup language protocol using a single API (application programming interface) negotiating with another system to determine if the other system supports the binary encoding protocol, wherein the markup language protocol is based on XML (eXtensible Markup Language), and wherein communication according to the binary encoding protocol comprises mapping from an XML schema to a binary encoding schema and generating a binary encoding from the binary encoding schema; if the other system supports the binary encoding protocol, the Web services stack communicating with the other system according to the binary encoding protocol; and if the other system does not support the binary encoding protocol, the Web services stack communicating with the other system according to the markup language protocol.
67. The computer-accessible storage medium as recited in claim 63 , wherein the binary encoding protocol uses Packed Encoding Rules (PER) encoding.