XQBE: a Visual Language for XML Data Management

Abstract

This Chapter describes a visual framework; called XQBE; that covers the most important aspects of XML data management; spanning the visualization of XML documents; the formulation of queries; the representation and specification of document schemata; the definition of integrity constraints; the formulation of updates; and the expression of reactive behaviors in response to data modifications. All these features are strongly unified by a common visual abstraction and a few recurrent paradigms; so as to provide a homogeneous and comprehensive environment that allows even users without advanced programming skills to deal with nontrivial XML data management and transformation tasks. The intrinsic ambiguity inherent in any visual representation of richly expressive languages required a considerable effort of formalization in the semantics of XQBE that eventually lead to a solution with major advantages in terms of intuitiveness. In other words; this means that the unique (and unambiguous) effect of a statement is the one the user would expect.