2062723
Active XML: A Data-Centric Perspective on Web Services
We propose in this chapter a peer-to-peer architecture that allows for the integration of distributed data and Web services. It relies on a language, Active XML, where documents embed calls to Web services that are used to enrich them, and new Web services may be defined by XQuery queries on such active documents. Embedding calls to functions or even to Web services inside data is not a new idea. Our contribution, however, is to turn them into a powerful tool for data and services integration. In particular, the language includes linguistic features to control the timing of service call activations. Various scenarios are captured, such as mediation, data warehousing and distributed computation. A first prototype is also described.
36162251
Active XML and Active Query Answers
XML and Web services are revolutioning the automatic management of distributed information, somewhat in the same way that HTML, Web browser and search engines modified human access to world wide information. We argue in this paper that the combination of XML and Web services allows for a novel query answering paradigm, where the exchanged information mixes materialized and intensional, active, information.
2374841
The Lowell database research self-assessment
Database needs are changing, driven by the Internet and increasing amounts of scientific and sensor data. In this article, the authors propose research into several important new directions for database management systems.
11518475
Adaptive on-line page importance computation
The computation of page importance in a huge dynamic graph has recently attracted a lot of attention because of the web. Page importance, or page rank is defined as the fixpoint of a matrix equation. Previous algorithms compute it off-line and require the use of a lot of extra CPU as well as disk resources (e.g. to store, maintain and read the link matrix). We introduce a new algorithm OPIC that works on-line, and uses much less resources. In particular, it does not require storing the link matrix. It is on-line in that it continuously refines its estimate of page importance while the web/graph is visited. Thus it can be used to focus crawling to the most interesting pages. We prove the correctness of OPIC. We present Adaptive OPIC that also works on-line but adapts dynamically to changes of the web. A variant of this algorithm is now used by Xyleme.We report on experiments with synthetic data. In particular, we study the convergence and adaptiveness of the algorithms for various scheduling strategies for the pages to visit. We also report on experiments based on crawls of significant portions of the web.
14211244
Querying and Updating Probabilistic Information in XML
We present in this paper a new model for representing probabilistic information in a semi-structured (XML) database, based on the use of probabilistic event variables. This work is motivated by the need of keeping track of both confidence and lineage of the information stored in a semi-structured warehouse. For instance, the modules of a (Hidden Web) content warehouse may derive information concerning the semantics of discovered Web services that is by nature not certain. Our model, namely the fuzzy tree model, supports both querying (tree pattern queries with join) and updating (transactions containing an arbitrary set of insertions and deletions) over probabilistic tree data. We highlight its expressive power and discuss implementation issues.
45906219
Issues in Monitoring Web Data
The web is turning from a collection of static documents to a global source of dynamic knowledge. First, HTML is increasingly complemented by the more structured XML format augmented with mechanisms for providing semantics such as RDF. Also, we believe that the very passive vision of web sites promoted by the current HTTP will soon turn into a much more active one based on pub/sub and web services. Thus, the monitoring of the web is likely to raise new challenges for many years. We consider here some applications involving web monitoring and some issues they raise.
42410314
Data Ring: Let Us Turn the Net into a Database!
Because of information ubiquity, one observes an important trend towards transferring information management tasks from database systems to networks. We introduce the notion of Data Ring that can be seen as a network version of a database or a content warehouse. A main goal is to achieve better performance for content management without requiring the acquisition of explicit control over information resources. We discuss the main traits of Data Rings and argue that Active XML provides an appropriate basis for such systems. 
 
The collaborating peers that form the Data Ring are autonomous, heterogeneous and their capabilities may greatly vary, e.g., from a sensor to a large database. To support effectively this paradigm of loose integration, the Data Ring enforces a seamless transition between data and metadata and between explicit and intentional data. It does not distinguish between data provided by web pages and data provided by web services, between local (extensional) data and external data obtained via a Web service call. This is achieved using the Active XML technology that is based on exchanging XML documents with embedded service calls both for the logical and physical data model.