726310
Exchanging intensional XML data
XML is becoming the universal format for data exchange between applications. Recently, the emergence of Web services as standard means of publishing and accessing data on the Web introduced a new class of XML documents, which we call intensional documents. These are XML documents where some of the data is given explicitly while other parts are defined only intensionally by means of embedded calls to Web services.When such documents are exchanged between applications, one has the choice of whether or not to materialize the intensional data (i.e., to invoke the embedded calls) before the document is sent. This choice may be influenced by various parameters, such as performance and security considerations. This article addresses the problem of guiding this materialization process.We argue that---like for regular XML data---schemas (à la DTD and XML Schema) can be used to control the exchange of intensional data and, in particular, to determine which data should be materialized before sending a document, and which should not. We formalize the problem and provide algorithms to solve it. We also present an implementation that complies with real-life standards for XML data, schemas, and Web services, and is used in the Active XML system. We illustrate the usefulness of this approach through a real-life application for peer-to-peer news exchange.
53236199
Exchanging Intensional XML Data
XML is becoming the universal format for data exchange between applications. Recently, the emergence of Web services as standard means of publishing and accessing data on the Web introduced a new class of XML documents, which we call intensional documents. These are XML documents where some of the data is given explicitly while other parts are defined only intensionally by means of embedded calls to Web services.When such documents are exchanged between applications, one has the choice to materialize the intensional data (i.e. to invoke the embedded calls) or not, before the document is sent. This choice may be influenced by various parameters, such as performance and security considerations. This paper addresses the problem of guiding this materialization process.We argue that, just like for regular XML data, schemas (ala DTD and XML Schema) may be used to control the exchange of intensional data and, in particular, to determine which data should be materialized before sending a document, and which should not. We formalize the problem and provide algorithms to solve it. We also present an implementation that complies with real life standards for XML data, schemas, and Web services, and is used in the Active XML system [3, 1].
38767
Inferring structure in semistructured data
When dealing with semistructured data such as that available on the Web, it becomes important to infer the inherent structure, both for the user (e.g., to facilitate querying) and for the system (e.g., to optimize access). In this paper, we consider the problem of identifying some underlying structure in large collections of semistructured data. Since we expect the data to be fairly irregular, this structure consists of an approximate classification of objects into a hierarchical collection of types. We propose a notion of a type hierarchy for such data, and outline a method for deriving the type hierarchy, and rules for assigning types to data elements.
2750139
Regular rewriting of active XML and unambiguity
We consider here the exchange of Active XML (AXML) data, i.e., XML documents where some of the data is given explicitly while other parts are given only intensionally as calls to Web services. Peers exchanging AXML data agree on a data exchange schema that specifies in particular which parts of the data are allowed to be intensional. Before sending a document, a peer may need to rewrite it to match the agreed data exchange schema, by calling some of the services and materializing their data. Previous works showed that the rewriting problem is undecidable in the general case and of high complexity in some restricted cases. We argue here that this difficulty is somewhat artificial. Indeed, we study what we believe to be a more adequate, from a practical view point, rewriting problem that is (1) in the spirit of standard 1-unambiguity constraints imposed on XML schema and (2) can be solved by a single pass over the document with a computational device not stronger than a finite state automation. Following previous works, we focus on the core of the problem, i.e., on the problem on words. The results may be extended to (A)XML trees in a straightforward manner.
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.
1932947
Representing and querying XML with incomplete information
We study the representation and querying of XML with incomplete information. We consider a simple model for XML data and their DTDs, a very simple query language, and a representation system for incomplete information in the spirit of the representations systems developed by Imielinski and Lipski [1984] for relational databases. In the scenario we consider, the incomplete information about an XML document is continuously enriched by successive queries to the document. We show that our representation system can represent partial information about the source document acquired by successive queries, and that it can be used to intelligently answer new queries. We also consider the impact on complexity of enriching our representation system or query language with additional features. The results suggest that our approach achieves a practically appealing balance between expressiveness and tractability.
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.
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.
46518675
Managing an XML Warehouse in a P2P Context
The paper is about warehousing XML content in a P2P environment. The role of an XML warehouse is to offer a centralized entry point to access a variety of information in an enterprise and provide functionalities to acquire, enrich, monitor and maintain this information. We consider a number of reasons to use a P2P approach to such warehouses, e.g., reducing the cost or sharing the management of information. We mention research issues that are raised.
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.
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).