14194921
Active XML, Security and Access Control
XML and Web services are revolutioning the automatic management of distributed information, somewhat in the same way that HTML, Web browsers 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 distributed data management paradigm, where the exchanged information mixes materialized and intensional, active, information. We illustrate the flexibility of this approach by presenting Active XML, a language that is based on embedding Web service calls in XML data. We focus on two particular issues, namely security and access control.
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.
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.
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.
40120481
Peer-to-peer warehousing of XML resources*
14872110
An Electronic Patient Record "on Steroids": Distributed, Peer-to-Peer, Secure and Privacy-conscious
This chapter investigates how an electronic patient record (EPR) document can be managed by a number of active XML (AXML) peers representing hospitals, MDs, insurance companies, and Department of Health. These peers are living on remote servers, laptops, and mobile devices. Each of them provides integrated information/filtering services, or a combination of these, such as a hospital provides information about visits, while an insurance company gives reimbursement reports, and access control on both of them is enforced by both the regulations of the Department of Health, and their own respective privacy policies. The chapter also illustrates how the distributed data can be queried by different users, and how the specified access control rules are enforced along the way. It also investigates how the queries are executed efficiently—only the relevant/permissible parts of the AXML document are exchanged among peers, an AXML peer can fully or partially evaluate a query by delegating some of the computation to filtering peers or information sources.
140229514
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 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. The research presented here was motivated by the Xyleme project at INRIA, whose objective it to develop a data warehouse for Web XML documents.
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.
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.
9349437
A Framework for Distributed XML Data Management
As data management applications grow more complex, they may need efficient distributed query processing, but also subscription management, data archival etc. To enact such applications, the current solution consists of stacking several systems together. The juxtaposition of different computing models prevents reasoning on the application as a whole, and wastes important opportunities to improve performance. 
 
We present a simple extension to the AXML [7] language, allowing it to declaratively specify and deploy complex applications based solely on XML and XML queries. Our main contribution is a full algebraic model for complex distributed AXML computations. While very expressive, the model is conceptually uniform, and enables numerous powerful optimizations across a distributed complex process.
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.