965218
Positive active XML
The increasing popularity of XML and Web services have given rise to a new generation of documents, called Active XML documents (AXML), where some of the data is given explicitly while other parts are given intensionally, by means of embedded calls to Web services. Web services in this context can exchange intensional information, using AXML documents as parameters and results.The goal of this paper is to provide a formal foundation for this new generation of AXML documents and services, and to study fundamental issues they raise. We focus on Web services that are (1) monotone and (2) defined declaratively as conjunctive queries over AXML documents. We study the semantics of documents and queries, the confluence of computations, termination and lazy query evaluation.
43817205
Constructing and Querying Peer-to-Peer Warehouses of XML Resources
We present KadoP, a distributed infrastructure for warehousing XML resources in a peer-to-peer framework. KadoP allows users to build a shared, distributed repository of resources such as XML documents, semantic information about such documents, Web services, and collections of such items. KadoP2P builds on distributed hash tables as a peer communication layer, and ActiveXML as a model for constructing and querying the resources in the peer network. We describe KadoP's data model, query language, and query processing paradigm.
43298690
A Test Platform for the INEX Heterogeneous Track
This article presents our work within the INEX 2004 Heterogeneous Track. We focused on taming the structural diversity within the INEX heterogeneous bibliographic corpus. 
 
We demonstrate how semantic models and associated inference techniques can be used to solve the problems raised by the structural diversity within a given XML corpus. The first step automatically extracts a set of concepts from each class of INEX heterogeneous documents. An unified set of concepts is then computed, which synthesizes the interesting concepts from the whole corpus. Individual corpora are connected to the unified set of concepts via conceptual mappings. This approach is implemented as an application of the KadoP platform for peer-to-peer warehousing of XML documents. While this work caters to the structural aspects of XML information retrieval, the extensibility of the KadoP system makes it an interesting test platform in which components developed by several INEX participants could be plugged, exploiting the opportunities of peer-to-peer data and service distribution.
40120481
Peer-to-peer warehousing of XML resources*
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.
52829094
Distributed Information Management with XML and Web Services
XML and Web services are revolutioning the automatic management of distributed information, somewhat in the same way HTML, Web browser and search engines modified human access to world wide information. To illustrate, we present Active XML that is based on embedding Web service calls inside XML documents. We mention two particular applications that take advantage of this new technology and novel research issues in this setting. This paper is based primarily on research at INRIA-Futurs in the Gemo Group, around XML and Web services (in particular, the Xyleme, Active XML and Spin projects).
5088023
Detecting changes in XML documents
We present a diff algorithm for XML data. This work is motivated by the support for change control in the context of the Xyleme project that is investigating dynamic warehouses capable of storing massive volumes of XML data. Because of the context, our algorithm has to be very efficient in terms of speed and memory space even at the cost of some loss of quality. Also, it considers, besides insertions, deletions and updates (standard in diffs), a move operation on subtrees that is essential in the context of XML. Intuitively, our diff algorithm uses signatures to match (large) subtrees that were left unchanged between the old and new versions. Such exact matchings are then possibly propagated to ancestors and descendants to obtain more matchings. It also uses XML specific information such as ID attributes. We provide a performance analysis of the algorithm. We show that it runs in average in linear time vs. quadratic time for previous algorithms. We present experiments on synthetic data that confirm the analysis. Since this problem is NP-hard, the linear time is obtained by trading some quality. We present experiments (again on synthetic data) that show that the output of our algorithm is reasonably close to the optimal in terms of quality. Finally we present experiments on a small sample of XML pages found on the Web.
13401760
Sharing Content in Structured P2P Networks
The development of Web standards and technologies has brought new opportunities for large-scale integration of Web content: data sources (such as XML, HTML, or PDF files), distributed applications (accessed via Web Services), and semantic information. At the same time, peerto- peer (P2P) platforms are being developed, and increasingly used for data management at the network scale. We present KADOP, a model, architecture, and system for sharing content in P2P. By building on distributed hash tables technology, XML indexing and query optimization techniques, and on the paradigm of active documents, KADOP enables the publication, discovery, and efficient exploitation of Web content in P2P. Thanks to intensional information, KADOP (i) is capable of run-time dynamic Web service composition, and (i) is open to external resources such as databases or other P2P networks.
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.
2990663
Extracting schema from semistructured data
Semistructured data is characterized by the lack of any fixed and rigid schema, although typically the data has some implicit structure. While the lack of fixed schema makes extracting semistructured data fairly easy and an attractive goal, presenting and querying such data is greatly impaired. Thus, a critical problem is the discovery of the structure implicit in semistructured data and, subsequently, the recasting of the raw data in terms of this structure. In this paper, we consider a very general form of semistructured data based on labeled, directed graphs. We show that such data can be typed using the greatest fixpoint semantics of monadic datalog programs. We present an algorithm for approximate typing of semistructured data. We establish that the general problem of finding an optimal such typing is NP-hard, but present some heuristics and techniques based on clustering that allow efficient and near-optimal treatment of the problem. We also present some preliminary experimental results.
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.