Design Of XML Concurrency Control Protocol

With the development of Internet, XML has gained great popularity in recent years and emerged as a new standard for data representation and exchange under, especially, by the promotion of W3C and leading computer companies. XML is being used in more and more areas. With the rapid adoption of XML, the Internet has been turned into agigantic database gradually.With the development of research on XML database management systems(XML DBMS), concurrent processing on mass XML data makes it very important to study the concurrency control protocols based on tree-structured XML data. The tree locking protocol, was defined based on static tree-structured data. However, XML data iterns are the dynamically changing tree-structured data. In accordance with the properties of XML data, a set of operations are defined, which can be used to change XML document from one tree-structured form to another legal tree-structured form. The most distinguished feature of this set of operations is that its operating object is a subtree, not a single node of the XML document.This characteristic fits for the XMIL data very much, because the valuable information of XML docum ent tree alllies in its leaves. Based on this set of operations, an XML dynamic tree protocol(XDTP)is presented and it is proved that this protocol, just like its static counterpart tree protocol, continues to ensure serializability and deadlock freedom in the presence of these operations. Experiments are conducted on the DBLP XML data set. The results of these experiments demonstrate that the XML dynamic tree protocol XDTP perform s very wellin this circumstance.