Pattern-Based Updates for the Web - Refinement of Syntax and Semantics in XChange

Several XML update languages have been developed in recent years, trying to fill a gap that was left behind by XML query and transformation languages. XML Update languages provide both an efficient and comfortable way of updating XML data, for which XML transformation languages are not feasible. One of them is the update language introduced as a part of the reactive language XChange. XChange’s update language follows a novel approach in that it uses a pattern-based syntax not only for the selection of data, but also for the identification of update positions. Previous works on XChange’s update language lack a clear language definition and formal semantics. This thesis introduces an update language called XChangeUp, a refinement of syntax and semantics of XChange’s update language. A solid and detailed language definition and formal declarative semantics are given for XChangeUp, capable not only of updating tree data (e.g. XML) but also updating graph data, which is very important in the Semantic Web. We also analyze several other update languages and their semantics and explain how XChangeUp’s approach to defining formal semantics has been inspired by them and where it deviates. Implementations of use cases proposed by W3C for the XQuery Update Facility illustrate XChangeUp’s elegance and expressive power, and comparisons with other update languages show advantages and disadvantages of XChangeUp’s pattern-based approach to updating Web data.