XML document versioning

Abstract

Managing multiple versions of XML documents represents an important problem, because of many applications ranging from traditional ones, such as software configuration control, to new ones, such as link permanence of web documents. Research on managing multiversion XML documents seeks to provide efficient and robust techniques for (i) storing and retrieving, (ii) exchanging, and (iii) querying such documents. In this paper, we first show that traditional version control methods, such as RCS, and SCCS, fall short from satisfying these three requirements, and discuss alternative solutions. First, we enhance RCS with a temporal page clustering policy to achieve objective (i). Then, we discuss a reference-based versioning scheme that achieves both objectives (i) and (ii) and is also effective at supporting simple queries. The topic of supporting complex queries, including temporal ones, meshes with the burgeoning interest of database researchers in XML as a database description language, and in XML query languages. In this context, the XML versioning problems are akin to those of transaction time management for databases of objects and semistructured information. Nevertheless, the need to preserve the natural ordering of XML documents frequently requires different techniques.