1. A system for extension of XQuery in a binary object XML repository, comprising: at least one XQuery interpreter module for implementing the XQuery language in the binary object XML repository; at least one function dispatcher module for implementing an XQuery function call mechanism, wherein a function is defined by the name of said function, the number of arguments taken by said function, and the datatypes of said arguments; at least one plug-in function library manager for implementing the client side of the binary object XML repository plug-in function application program interface; and at least one dynamically-linked plug-in function library module for implementing the server side of the binary object XML repository plug-in function application program interface.