Emmanuel Pietriga

VXT: a visual approach to XML transformations

The domain of XML transformations is becoming more and more important as a result of the increasing number of applications adopting XML as their format for data exchange or representation. Most of the existing solutions for expressing XML transformations are textual languages, such as XSLT or DOM combined with a general-purpose programming language. Several tools build on top of these languages, providing a graphical environment. Transformations are however still specified in a textual way using the underlying language (often XSLT), thus requiring the user to learn the associated textual language.We believe that visual programming techniques are well-suited to representing XML structures and make the specification of transformations simpler. We present a visual programming language for the specification of XML transformations in an interactive environment, based on a zoomable user interface toolkit. Transformations can be run from the application or exported to two target languages: XSLT and Circus, a general-purpose structure transformation language designed by the second author and briefly introduced in this paper.

VXT: Visual XML Transformer

The ever-growing amount of heterogeneous data exchanged via the Internet, combined with the popularity of XML, makes structured document transformations an increasingly important application domain. Most of the existing solutions for expressing XML transformations are textual languages, such as XSLT (Extensible Stylesheet Language Transformations) or DOM (Document Object Model), combined with a general-purpose programming language. Several tools build on top of these languages, providing a graphical environment and debugging facilities. Transformations are, however, still specified in a textual way using the underlying language (often XSLT), thus requiring users to learn it. We believe that visual programming techniques are well-suited to representing XML structures and make the specification of transformations simpler. We propose a visual language, called VXT (Visual XML Transformer), for the specification of XML transformations in an interactive environment based on a zoomable user interface toolkit and on two target languages specialised in structure transformations: Circus and XSLT.

Experimenting with the circus language for XML modeling and transformation

After a brief introduction to the Circus programming language, we present a simple type set to model XML structures. We then describe a transformation that takes a mail as input and produces a reply, showing how subtyping is used in order to refine the type control and specialize the transformation. Conclusions are drawn both on our (easy to use but clearly limited) XML data model and on Circus itself ; expected qualities of the language are verified ; the need for some new features is expressed. Finally, we sketch some language extensions, a richer model for XML structures, and explain our choices and expectations.

A formal study of a visual language for the visualization of document type definition

This formal study proposes a transformational approach to the definition of general purpose visual languages based on hierarchical structures, addressing more specifically DTD visualization as its application area. We show that such visual languages can be constructed through progressive refinement of a syntax based on nested/juxtaposed rectangles. Several transformation stages, which can all be formally characterized, produce a high quality visual representation which expresses the fundamental properties of the original structure. Moreover, this approach opens some perspectives in proving visual properties through standard mathematical tools such as inductive proofs, thus establishing some practical links between visual language theory and classical language theory.