EXTENSION OF SCHEMATIZED XML PROTOCOLS

An application using one version of a schematized XML protocol communicates with another application using a different version of the schematized XML protocol. The different versions may correspond to different deployments or releases of the protocol. Each application generates messages to be sent using two data sets. A first data set is incorporated into the message using elements available in a standard XML protocol schema. A second data set is incorporated into the message using XML annotation elements. The receiving application processes the message using the schematized XML protocol to parse out the first data set. The receiving application further parses the message to identify the second data set that is carried by enhanced XML annotation elements. Extension or annotations are flexibly added to the XML protocol without requiring the client application to request—or the server application to respond to—a pre-negotiated number or type of annotations.