Dynamic XML documents with distribution and replication

Abstract

The advent of XML as a universal exchange format, and of Web services as a basis for distributed computing, has fostered the apparition of a new class of documents: dynamic XML documents. These are XML documents where some data is given explicitly while other parts are given only intensionally by means of embedded calls to web services that can be called to generate the required information. By the sole presence of Web services, dynamic documents already include inherently some form of distributed computation. A higher level of distribution that also allows (fragments of) dynamic documents to be distributed and/or replicated over several sites is highly desirable in today's Web architecture, and in fact is also relevant for regular (non dynamic) documents.The goal of this paper is to study new issues raised by the distribution and replication of dynamic XML data. Our study has originated in the context of the Active XML system [1,3,22] but the results are applicable to many other systems supporting dynamic XML data. Starting from a data model and a query language, we describe a complete framework for distributed and replicated dynamic XML documents. We provide a comprehensive cost model for query evaluation and show how it applies to user queries and service calls. Finally, we describe an algorithm that, for a given peer, chooses data and services that the peer should replicate to improve the efficiency of maintaining and querying its dynamic data.

An Efficient Replicated Data Management Approach for Peer-to-Peer Systems

“…ActiveXML [11] is a declarative framework that harnesses web services for data integration, and is put to work in a peer-to-peer architecture. It supports the definition of replicated XML fragments as Web service calls but does not address update propagation.…”

A Tale of Two Schemas: Creating a Temporal XML Schema from a Snapshot Schema with τXSchema

“…τXSchema is a system for constructing schemas for time-varying XML documents 1 . A time-varying document records the evolution of a document over time, i.e., all of the versions of the document.…”

“…But we assume that the schema itself is fixed, with no element types, data types, or attributes being added to or removed from the schema over time. Intensional XML data (also termed dynamic XML documents [1]), that is, parts of XML documents that consist of programs that generate data [26], are gaining popularity. Incorporating intensional XML data is beyond the scope of this paper.…”

Schema-driven Customization of Web Services

“…The demonstrated software was developed in the context of Active XML [3,1,9,2], a peer-to-peer system that natively supports intensional documents and the declarative speci cation of Web services using XQuery [12]. We propose a new approach that allows one to control and customize the exchange of intensional documents between Active XML peers, but the same principles can be employed for exchanges between arbitrary Web applications.…”