Vincent Quint

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.

A structured authoring environment for the World-Wide Web

Abstract Authoring documents for the World-Wide Web is not always an easy task. Most authors either directly type HTML syntax with a text editor or convert files that they produce with various document preparation systems, but both methods pose problems. We propose another approach, based on a structured document editor, Grif. The main characteristics of HTML documents are analyzed and the extensions that these documents have imposed to the Grif editor are presented. With these extensions, Grif becomes a comfortable environment for authoring WWW documents, and it allows better and more rigorously structured documents to be produced. It also allows a smooth evolution towards SGML.

Techniques for authoring complex XML documents

This paper reviews the main innovations of XML and considers their impact on the editing techniques for structured documents. Namespaces open the way to compound documents; well-formedness brings more freedom in the editing task; CSS allows style to be associated easily with structured documents. In addition to these innovative features the wide deployment of XML introduces structured documents in many new applications including applications where text is not the dominant content type. In languages such as SVG or SMIL for instance XML is used to represent vector graphics or multimedia presentations. This is a challenging situation for authoring tools. Traditional methods for editing structured documents are not sufficient to address the new requirements. New techniques must be developed or adapted to allow more users to efficiently create advanced XML documents. These techniques include multiple views semantic-driven editing direct manipulation concurrent manipulation of style and structure and integrated multi-language editing. They have been implemented and experimented in the Amaya editor and in some other tools.

Combining hypertext and structured documents in Grif

This paper presents the experience gained in developing and using the hypertext functions of the Grif systeml. Grif is a structured document editor based on the generic structure concept: each document is represented in the system by it~ logical structure which is an instance of a generic structure. This notion of logical structure encompasses both hierarchical structures (as is usual in structured documents) and non-hierarchical links (as is usual in hypertext). The document model on which Grif is based is presented, focusing on the different types of links. Various applications using these links are also described. It is shown that the approaches of elect ronic documents and hypertext, which are often opposed to each other, can be combined for building more powerful integrated systems.

Timesheets.js: when SMIL meets HTML5 and CSS3

In this paper, we explore different ways to publish multimedia documents on the web. We propose a solution that takes advantage of the new multimedia features of web standards, namely HTML5 and CSS3. While JavaScript is fine for handling timing, synchronization and user interaction in specific multimedia pages, we advocate a more generic, document-oriented alternative relying primarily on declarative standards: HTML5 and CSS3 complemented by SMIL Timesheets. This approach is made possible by a Timesheets scheduler that runs in the browser. Various applications based on this solution illustrate the paper, ranging from media annotations to web documentaries.

On the analysis of cascading style sheets

Developing and maintaining cascading style sheets (CSS) is an important issue to web developers as they suffer from the lack of rigorous methods. Most existing means rely on validators that check syntactic rules, and on runtime debuggers that check the behavior of a CSS style sheet on a particular document instance. However, the aim of most style sheets is to be applied to an entire set of documents, usually defined by some schema. To this end, a CSS style sheet is usually written w.r.t. a given schema. While usual debugging tools help reducing the number of bugs, they do not ultimately allow to prove properties over the whole set of documents to which the style sheet is intended to be applied. We propose a novel approach to fill this lack. We introduce ideas borrowed from the fields of logic and compile-time verification for the analysis of CSS style sheets. We present an original tool based on recent advances in tree logics. The tool is capable of statically detecting a wide range of errors (such as empty CSS selectors and semantically equivalent selectors), as well as proving properties related to sets of documents (such as coverage of styling information), in the presence or absence of schema information. This new tool can be used in addition to existing runtime debuggers to ensure a higher level of quality of CSS style sheets.

Identifying query incompatibilities with evolving XML schemas

During the life cycle of an XML application, both schemas and queries may change from one version to another. Schema evolutions may affect query results and potentially the validity of produced data. Nowadays, a challenge is to assess and accommodate the impact of these changes in evolving XML applications. Such questions arise naturally in XML static analyzers. These analyzers often rely on decision procedures such as inclusion between XML schemas, query containment and satisfiability. However, existing decision procedures cannot be used directly in this context. The reason is that they are unable to distinguish information related to the evolution from information corresponding to bugs. This paper proposes a predicate language within a logical framework that can be used to make this distinction. We present a system for monitoring the effect of schema evolutions on the set of admissible documents and on the results of queries. The system is very powerful in analyzing various scenarios where the result of a query may not be anymore what was expected. Specifically, the system is based on a set of predicates which allow a fine-grained analysis for a wide range of forward and backward compatibility issues. Moreover, the system can produce counterexamples and witness documents which are useful for debugging purposes. The current implementation has been tested with realistic use cases, where it allows identifying queries that must be reformulated in order to produce the expected results across successive schema versions.

Impact of XML Schema Evolution

We consider the problem of XML Schema evolution. In the ever-changing context of the web, XML schemas continuously change in order to cope with the natural evolution of the entities they describe. Schema changes have important consequences. First, existing documents valid with respect to the original schema are no longer guaranteed to fulfill the constraints described by the evolved schema. Second, the evolution also impacts programs, manipulating documents whose structure is described by the original schema. We propose a unifying framework for determining the effects of XML Schema evolution both on the validity of documents and on queries. The system is very powerful in analyzing various scenarios in which forward/backward compatibility of schemas is broken, and in which the result of a query may no longer be what was expected. Specifically, the system offers a predicate language that allows one to formulate properties related to schema evolution. The system then relies on exact reasoning techniques to perform a fine-grained analysis. This yields either a formal proof of the property or a counter-example that can be used for debugging purposes. The system has been fully implemented and tested with real-world use cases, in particular with the main standard document formats used on the web, as defined by W3C. The system precisely identifies compatibility relations between document formats. In case these relations do not hold, the system can identify queries that must be reformulated in order to produce the expected results across successive schema versions.

Editing with style

HTML has popularized the use of style sheets, and the advent of XML has stressed the importance of style as a key area complementing document structure and content. A number of tools are now available for producing HTML and XML documents, but very few are addressing style issues. In this paper we analyze the requirements for style manipulation tools, based on the main features of the CSS language. We discuss methods and techniques that meet these requirements and that can be used to efficiently support web authors in style sheet manipulation. The discussion is illustrated by the recent developments made in the Amaya web authoring environment.

Templates, microformats and structured editing

Microformats and semantic XHTML add semantics to web pages while taking advantage of the existing (X)HTML infrastructure. This approach enables new applications that can be deployed smoothly on the web. But there is currently no way to describe rigorously this type of markup and authors of web pages have very little help for creating and encoding semantic markup. A language that addresses these issues is presented in this paper. Its role is to specify semantically rich XML languages in terms of other XML languages, such as XHTML. The language is versatile enough to represent templates that can capture the overall structure of large documents as well as the fine details of a microformat. It is supported by an editing tool for producing documents encoded in a semantically rich markup language, still fully compatible with XHTML.