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.
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.
31547105
Secure Exchange of Modifiable Data and Queries
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].
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.
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).
6193947
Schema-driven Customization of Web Services
Publisher Summary This chapter discusses schema-driven customization of Web services. Web services are emerging as a standard mean of publishing and accessing data on the Web, by providing a standard XML-based protocol to invoke remote programs over the Web (simple object access protocol (SOAP)), along with a standard language to describe them (web service description language (WSDL)). XML is becoming the universal format for data exchange between applications. Recently, the use of XML documents, where some of the data is given explicitly, while other parts are defined by programs that generate the relevant data, started gaining popularity. This chapter refers to such documents as intensional documents. Materialization is the process of invoking some of the programs included in an XML document and replacing them by their results. The goal of this demonstration is to advocate for the exchange of such intensional XML documents between applications, and to illustrate the new possibilities and the great flexibility they bring to application design.
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.
18359310
Digital signatures for modifiable collections
The common assumption about digital signatures is that they disallow any kind of modification on signed data. However, a more flexible approach is often needed and has been advocated lately, one in which some restricted modifications may still occur, without invalidating the data. This is made possible by offering signatures which are homomorphic with respect to some operation on the message domain. Starting from the signature(s) of some data instance(s), computed by the data owner, anybody else can derive the signature corresponding to a new data instance, if obtained only via some accepted operation from the previous one(s). More, updated signatures should be indistinguishable from the ones computed by the data owner and this updating step should be applicable as many times as needed. This paper deals with the signing of insert-only collections, in which element insertions are accepted but no removals should occur. Newly inserted elements do not have to be signed or known by the initial signer. We propose two techniques: one which transposes the insert-only problem into a delete-only one (which is already solved), and another technique based on zero-knowledge proofs. We also give performance measures and discuss applications.
11287865
The Data Ring: Community Content Sharing
Information ubiquity has created a large crowd of users (most notably scientists), who could employ DBMS technol- ogy to process and share their data more e!ec tively. Still, this user base prefers to keep its data in files that can be easily managed by applications such as spreadsheets, rather than deal with the complexity and rigidity of modern database systems. In this paper, we propose a vision for enabling non-experts, such as scientists, to build content sharing communities in a true database fashion: declaratively. The proposed infras- tructure, called the data ring, enables users to manage and share their data with minimal e! ort; the user points to the data that should be shared, and the data ring becomes re- sponsible for automatically indexing the data (to make it accessible), replicating it (for availability), and reorganiz- ing its physical storage (for better query performance). We outline the salient features of our proposal, and outline re- search challenges that must be addressed in order to realize this vision.