Eun Jung Lee

The KIPS Transactions:PartD, Vol. 11, No. 7, pp. 1367-1374, Dec. 2004
10.3745/KIPSTD.2004.11.7.1367,   PDF Download:

Abstract

For sharing XML data by many users, a way of concurrency and access control is required for isolating update actions such as inserting and deleting subtrees. Existing locking mechanisms as 2PL or MGL suffer low concurrency when applied to tree structures. In this paper, list data sharing model is proposed based on the semantics expressed in DTD. In this model, tree updating actions such as inserting and deleting subtrees are considered only for the repetitive parts of XML trees. The proposed model guarantees that the result XML tree after applying a tree updating action is always valid, even when multiple users access the tree at the same time. Also, a new locking mechanism called list locking protocol is proposed. The new locking protocol is expected to show better accessiility with less number of locking objects compared to the Helmer's OO2PL model. Since update actions on a shared XML tree usually applied to the repetitive parts of the tree, the proposed model is expected to provide a useful way for efficient data sharing when conbined with previous locking methods on terminal node data.

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