A Graph-based Concurrency Control Protocol for Xml Metadata Knowledge Bases

Providing efficient access for XML APIs in XML metadata knowledge bases (XMKBs) is crucial, since XML is widely used to integrate data in XMKBs. In XMKBs, the types, contents and locations of heterogeneous data are illustrated in XML documents to provide a uniform interface for users to manipulate this data. As users update and query information about this heterogeneous data, the XML documents are manipulated by XML APIs (i.e., DOM APIs) to ensure consistency. Concurrency control protocols can ensure a better performance of the DOM APIs to manipulate XML documents. However, the existing protocols (i.e., traditional locking protocols and XML-based protocols) are not sufficiently adequate for DOM APIs in XMKBs. Traditional graph-based locking protocols cannot deal with new DOM operations, and the existing XML-based protocols treat XML documents as trees, with no regard for the ID/IDREF(s) used in them. This paper proposes a new XML graph-based concurrency control protocol, tailored for XMKBs, named XGP. The novel feature of XGP is to analyze the DOM APIs on XML document graphical structures to increase the transactional performance of XMKBs. Our simulated results show that our XGP outperforms other concurrency control protocols in terms of