Catálogo de publicaciones - libros

Users without knowledge of schemas or query languages have difficulties in accessing information stored in databases. Commercial and research efforts have focused on keyword-based searches. Among them, précis queries generate entire multi-relation databases, which are logical subsets of existing ones, instead of individual relations. The logical database subset contains not only items directly related to the query selections but also items implicitly related to them in various ways. Earlier work has identified the need of providing the naïve user with meaningful answers to his questions and has suggested the translation of précis query answer in narrative form. In this paper, we present a semi-automatic method that translates the relational output of a précis query into a synthesis of results. We describe a translator engine that uses a template mechanism for generating a précis in a narrative form through a set of reusable templates.

Data security is well-recognized a vital issue in an information system that is supported in an outsource environment. However, most of conventional XML encryption proposals treat confidential parts of an XML document as whole blocks of text and apply encryption algorithms directly on them. As a result, queries involving the encrypted part cannot be efficiently processed. In order to address these problems, we propose XQEnc, a novel approach to support querying encrypted XML. XQEnc is based on two important techniques of vectorization and skeleton compression. Essentially, vectorization, which is a generalization of columns of a relational table, makes use the basic path of an XML tree to label the data values. Skeleton compression collapses the redundant paths into a multiplicity attribute. Our analysis and experimental study shows that XQEnc achieves both better query efficiency and more robust security compared with conventional methods. As an application, we show how XQEnc can be realized with relational techniques to enable secure XML data outsourcing.

The PDF format represents the de facto standard for print-oriented documents. In this paper we address the problem of wrapping PDF documents, which raises new challenges in the information extraction field. The proposal is based on a novel bottom-up wrapping approach to extract information tokens and integrate them into groups related according to the logical structure of a document. A PDF wrapper is defined by specifying a set of group type definitions which impose a target structure to token groups containing the required information. Due to the intrinsic uncertainty on the structure and presentation of PDF documents, we devise constraints on token groupings as fuzzy logic conditions. We define a formal semantics for PDF wrappers and propose an algorithm for wrapper evaluation working in polynomial time with respect to the size of a PDF document.

The development of collaborative environments that not only manage information and communication, but also support the actual work processes of organisations is very important. XML documents are increasingly being used to mark up various kinds of data from web content to data used by applications. Often these documents need to be collaboratively created and edited by a group of users. In this paper we present a flexible solution for supporting collaboration over shared repositories containing both XML and text documents. By adopting hierarchical document models instead of linear representations used in most editing systems, the level of conflict granularity and resolution can be varied dynamically and the semantics of the user operations can be easily expressed. Merging of user work is based on the operations performed rather than the document states which provides a less complex and more appropriate way of handling conflicts.

The paper describes the conceptualisation process in the ReQuest approach, a wide-spectrum methodology for web-based information systems analysis and development. This methodology includes a strong involvement of end users in the requirement elicitation process by building prototype user interface fragments of the future application. The paper focuses on the analysis step of these fragments that yields a draft conceptual schema of the application domain. The analysis includes a tree-based representation of the fragments, the detection of shared subtrees through mining techniques, their normalisation and the derivation of the conceptual schema. A short description of a supporting tool is given.

Given a service request such as scheduling an appointment or purchasing a product, it is possible that the invocation of the service results in too many solutions that all satisfy the constraints of the request or in no solution that satisfies all the constraints. When the invocation results in too many solutions or no solution, a resolution process becomes necessary for agreeing on one of the solutions or finding some agreeable resolution. We address this problem by imposing an ordering over all solutions and over all near solutions. This ordering provides a way to select the best- with dominated solutions or dominated near solutions eliminated. Further, we provide an expectation-based resolution process that can take the initiative and either elicit additional constraints or suggest which constraints should be relaxed. Experiments with our prototype implementation show that this resolution process correlates substantially with human behavior and thus can be effective in helping users reach an acceptable resolution for their service requests.

Developing service-centric applications will require developers to discover candidate services during requirements processes. However such discovery is challenging due to the ontological mismatch between requirement and service descriptions. We propose patterns to re-express requirements-based service queries using classes of solution service, to increase the likelihood of discovering relevant services from service registries. We report a prototype pattern language developed for service-based vehicle fleet management, and demonstrate its use with an example.

One important aspect in building trusted information systems is the precise specification of systems and system parts. This applies even more for information systems built from COTS components. To specify behavioral aspects of software components the UML Object Constraint Language (OCL) is well suited. One current problem in component specifications comes from the fact that editing OCL constraints manually is time consuming and error-prone. To simplify constraint definition we propose to use specification patterns for which OCL constraints can be generated automatically. In this paper we outline this solution proposal and present a library of reusable OCL specification patterns.

Business processes are often characterized by high variability and dynamics, which cannot be always captured in contemporary process management systems (PMS). Adaptive PMS have emerged in recent years, but do not completely solve this problem. In particular, users are not adequately supported in dealing with real–world exceptions. Exception handling usually requires manual interactions and necessary process adaptations have to be defined at the control flow level. Altogether, only experienced users are able to cope with these tasks. As an alternative, changes on process data (elements) can be more easily accomplished, and a more data–driven view on (adaptive) PMS can help to bridge the gap between real–world processes and computerized ones. In this paper we present an approach for data–driven process control allowing for the automated expansion and adaptation of task nets during runtime. By integrating and exploiting context information this approach further enables automated exception handling at a high level and in a user–friendly way. Altogether, the presented work provides an added value to current adaptive PMS.

This paper presents a classification framework for workflow exception handling in the form of patterns. This framework is independent of specific modelling approaches or technologies and as such provides an objective means of delineating the exception-handling capabilities of specific workflow systems. It is subsequently used to assess the level of exceptions support provided by eight commercial workflow systems and business process modelling and execution languages. On the basis of these investigations, we propose a graphical, tool-independent language for defining exception handling strategies in workflows.