Catálogo de publicaciones - libros

This paper introduces a method and a tool for automatically aligning OWL ontologies, a crucial step for achieving the interoperability of heterogeneous systems in the Semantic Web. Different components are combined for finding suitable mapping candidates (together with their weights), and the set of rules with maximum matching probability is selected. Machine learning-based classifiers and a new classifier using the structure and the semantics of the OWL ontologies are proposed. Our method has been implemented and evaluated on an independent test set provided by an international ontology alignment contest. We provide the results of this evaluation with respect to the other competitors.

This paper describes MEAT (Memory of Experiments for the Analysis of Transcriptomes), a project aiming at supporting biologists working on DNA microarrays. We provide methodological and software support to build an experiment memory for this domain. Our approach, based on Semantic Web Technologies, is relying on formalized ontologies and semantic annotations of scientific articles and other knowledge sources. It can probably be extended to other massive analyses of biological events (as provided by proteomics, metabolomics...).

As documents containing sensitive information are exchanged over the Internet, access control of XML documents is becoming important. Access control policies can specify fine-grained rules to documents, but policies sometimes become redundant, as documents are restructured or combined during exchange. In this paper, we consider a new approach of optimizing access control policies, by extracting distribution information of given authorization values within XML data. The extracted information is called a global policy tree, and it can be utilized for minimizing the total size of policies as well as efficient query processing. We present a linear-time algorithm for minimizing policies utilizing global policy trees, and our evaluation results show significant improvement over existing work.

The problem of repairing XML data which are inconsistent and incomplete with respect to a set of integrity constraints and a DTD is addressed. The existence of repairs (i.e. minimal sets of update operations making data consistent) is investigated and shown to be undecidable in the general case. This pro-blem is shown to be still undecidable when data are interpreted as “incomplete” (so that they could be repaired by performing insert operations only). However, it becomes decidable when particular classes of constraints are considered. The existence of repairs is proved to be decidable and, in particular, $\mathcal{NP}$ -complete, if inconsistent data are interpreted as “dirty” data (so that repairs are data-cleaning operations consisting in only deletions). The existence of general repairs (containing both insert and delete operations) for special classes of integrity constraints (functional dependencies) is also investigated. Finally, for all the cases where the existence of a repair is decidable, the complexity of providing consistent answers to a query (issued on inconsistent data) is characterized.

This paper first proposes a two-step approach to define rules for maintaining materialized XML views specified over relational databases. The first step concentrates on identifying all paths of the base schema that are relevant to a path of the view, with respect to an update. The second step creates rules that maintain all view paths that can be affected by the update. The paper then discusses how to automatically identify all paths in the base schema that are relevant to a view path with respect to a given update operation and how to create the appropriate maintenance rules.

The incorporation of Adaptive Navigation techniques into Web applications is a complex task. The conceptual specification of the navigation must consider the preferences and needs of users, as well as different implementation alternatives from the same navigational structure. However, there is a lack of methods that rule this integration. This work proposes a methodological approach that allow describing adaptive navigation characteristics of a Web application at a high abstraction level. We introduce a User Modelling process and a set of concepts that permit to incorporate two types of adaptive navigation techniques into the navigational description of a Web application. These techniques select and sort the links of a page, according to their relevance for a given user. The steps of the methodology are illustrated through a case study.

Web services are introduced to deliver methods and technologies to help organizations link their software. However, existing web service standards based on WSDL limits web services’ usefulness in collaborative process management. In this paper, we present a framework, WSCPC, that enables web service based collaborative process management in heterogeneous software environment. To facilitate web service based collaboration, we propose semantic service models and a web service extension that overcome limitations in current frameworks, and, hence, support complex level of communications needed for intensive collaboration in heterogeneous Virtual Enterprises environment. Through our semantic service models, organizational functionalities and capabilities are encapsulated and published as services. Collaborating partners can schedule, control, and monitor the relevant functionalities through WSCPC web services interactions model and web service extensions.

Online auction sites have very specific workloads and user behavior characteristics. Previous studies on workload characterization conducted by the authors showed that i) bidding activity on auctions increases considerably after 90% of an auction’s life time has elapsed, ii) a very large percentage of auctions have a relatively low number of bids and bidders and a very small percentage of auctions have a high number of bids and bidders, iii) prices rise very fast after an auction has lasted more than 90% of its life time. Thus, if bidders are not able to successfully bid at the very last moments of an auction because of site overload, the final price may not be as high as it could be and sellers, and consequently the auction site, may lose revenue. In this paper, we propose server-side caching strategies in which cache placement and replacement policies are based on auction-related parameters such as number of bids placed or percent remaining time till closing time. A main-memory auction cache at the application server can be used to reduce accesses to the back-end database server. Trace-based simulations were used to evaluate these caching strategies in terms of cache hit ratio and cache efficiency.

For efficiently managing Web Services (WS) transactions which are executed across multiple loosely-coupled autonomous organizations, isolation is commonly relaxed. A Web services operation of a transaction releases locks on its resources once its jobs are completed without waiting for the completions of other operations. However, those early unlocked resources can be seen by other transactions, which can spoil data integrity and causes incorrect outcomes. Existing WS transaction standards do not consider this problem. In this paper, we propose a mechanism to ensure the consistent executions of isolation-relaxing WS transactions. The mechanism effectively detects inconsistent states of transactions with a notion of a completion dependency and recovers them to consistent states. We also propose a new Web services Transaction Dependency management Protocol (WTDP). WTDP helps organizations manage the WS transactions easily without data inconsistency. WTDP is designed to be compliant with a representative WS transaction standard, the Web Services Transactions specifications, for easy integration into existing WS transaction systems. We prototyped a WTDP-based WS transaction management system to validate our protocol.

Web services enable the design, integration, composition, and deployment of distributed and heterogeneous software. While most syntactic issues in composition have been taken care of somewhat satisfactorily, several semantic issues remain unresolved. In this paper, we consider issues relating to binding and execution of composite services. A Web service composition or composite activity consists of a set of (basic or composite) activities with some ordering constraints. In general, an arbitrary collection of execution instances of the individual activities may not constitute an execution of the composite activity; the individual execution instances must be “compatible”. In this paper, we propose (a) a simple formalism to express the compatibility requirements in a composition, and (b) a methodology for (i) the selection of a composite service provider for a composite activity and (ii) the selection of (other) service providers for the constituent activities of the composite activity, to ensure an execution of the composition satisfying the compatibility requirements.