A Visual Approach to Authoring XPath Expressions

Web metadata is crucial for providing machine-understandable descriptions of Web resources, and has a number of applications such as discovery, qualification, and adaptation of Web contents. While metadata is often embedded into a target document, metadata can also be associated externally by means of an addressing scheme such as the XPath language. However, creation and modification of external metadata solely with a conventional editor is not easy because metadata authoring involves the maintenance and elaboration of addressing expressions as well as editing individual documents. The objective of this study is to advance extensibility in the design of annotation editors with particular emphasis on a visual approach to authoring XPath expressions. The key idea behind the XPath authoring process is to facilitate flexibility in the creation of XPath expressions as a result of the seamless integration of three authoring methods: instantaneous creation, context-constrained creation, and manual creation. In this paper, we briefly introduce a framework for external annotation first, and give a high-level overview of our annotation editor. The three XPath creation methods are then explained, showing examples of XPath expressions and the graphical user interface for visual authoring process. Finally, we present our annotation editor developed with the visual XPath authoring capability, and show how the annotation editor is customized for an annotation vocabulary at hand.