Exchanging intensional XML data

Tova Milo*, Serge Abiteboul, Bernd Amann, Omar Benjelloun, Fred Dang Ngoc

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review


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 denned 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.

Original languageEnglish
Pages (from-to)1-40
Number of pages40
JournalACM Transactions on Database Systems
Issue number1
StatePublished - Mar 2005


  • Data exchange
  • Intensional information
  • Typing
  • Web services
  • XML


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