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In many applications information about the history of data and their dynamic aspects are just as important as static information. During the last years the increasing amount of information accessible through the Web has presented new challenges to academic and industrial research on database. In this context, data are either structured, when coming from relational or object-oriented databases, or partially or completely unstructured, when they consist of simple collections of text or image files. In the context of semistructured data, models and query languages must be extended in order to consider dynamic aspects. We present a model based on labeled graphs for representing changes in semistructured data and a SQL-like query language for querying it

The diffusion of clinical guidelines to describe the proper way to deal with patients? situations is spreading out and opens new issues in the context of modeling and managing (temporal) information about medical activities. Guidelines can be seen as processes describing the sequence of activities to be executed, and thus approaches proposed in the business context can be used to model them. In this paper, we propose a general conceptual workflow model, considering both activities and their temporal properties, and focus on the representation of clinical guidelines by the proposed model

tXSchema (Currim et al., 2004) is a framework (a language and a suite of tools) for the creation and validation of time-varying XML documents. A tXSchema schema is composed of a conventional XML Schema annotated with physical and logical annotations. All components of a tXSchema schema can evolve over time to reflect changes in the real-world. Since many applications need to keep track of both data and schema evolution, schema versioning has been long advocated to be the best solution to do this. In this paper, we complete the tXSchema framework, which is predisposed from the origin to support schema versioning, with the definition of the operations which are necessary to exploit such feature and make schema versioning functionalities available to final users. Moreover, we propose a new technique for schema versioning in tXSchema, allowing a complete and safe management of schema changes. It supports both versioning of conventional schema and versioning of annotations, in an integrated manner. For each component of a tXSchema schema, our approach provides a complete and sound set of change primitives and a set of high-level change operations, for the maintenance of such a component and defines their operational semantics.

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