Improvements in distribution, replication and security of Dynamic XML Documents

The power of distribution and replication has been harnessed since long to provide potential advantages of improved performance, reduced costs, improved reliability and shorter response times. Recently, these powers have been introduced for dynamic XML documents as new features. The goal of this paper is to propose a proper unit of fragmentation for the AXML documents, so that the document remains valid while it is distributed and replicated. To address the communication cost and performance related issues, we propose an optimized query processing strategy while data is distributed and replicated over different peers using semi-join operation. A more secured and reliable security model in distributed environment has also been proposed.

What we did?

We have addressed new challenges posed by the introduction of dynamicity in distribution and replication in XML based documents over web. The entire work is divided into two parts. Firstly, a proper framework for fragmentation was found and an optimized query processing was proposed in a distributed environment. Since in AXML a part of document needs to be distributed, we need to build a mechanism by which validity of document can be checked at different peers. So we proposed the definition of a valid fragment and use of DTD at each peer.

Secondly, we introduced a more reliable security model, which effectively addresses the specific security issues arising due to distribution and replication of AXML documents over Internet. We proposed an object oriented security model similar to the model proposed in Legion system developed at University of Arizona that gives every user, flexibility to decide level of security and policies as per his/her own requirement and discretion. It ensures proper agreement between peers by using the two-way authentication mechanism. It also supports the feature for caching and expiry time of licenses at service provider’s end and thus opens possibility of easy revocation of licenses. [PDF]