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A broad spectrum of data is available on the Web in distinct heterogeneous sources, and stored under different formats. As the number of systems that utilize this heterogeneous data grows, the importance of data translation and conversion mechanisms increases greatly. In this paper we present a new translation system, based on schemamatching, aimed to simplify the intricate task of data conversion. We observe that in many cases the schema of the data in the source system is very similar to the that of the target system. In such cases, much of the translation work can be done automatically, based on the schemas similarity. This saves a lot of effort for the user, limiting the amount of programming needed. We define common schema and data models, in which schemas and data (resp.) from many common models can be represented. Using a rulebased method, the source schema is compared with the target one, and each component in the source schema is matched with a corresponding compone...

The Strudel system applies concepts from database management systems to the process of building Web sites. Strudel's key idea is separating the management of the site's data, the creation and management of the site's structure, and the visual presentation of the site's pages. First, the site builder creates a uniform model of all data available at the site. Second, the builder uses this model to declaratively define the Web site's structure by applying a "site-definition query" to the underlying data. The result of evaluating this query is a "site graph", which represents both the site's content and structure. Third, the builder specifies the visual presentation of pages in Strudel's HTML-template language. The data model underlying Strudel is a semi-structured model of labeled directed graphs. We describe Strudel's key characteristics, report on our experiences using Strudel, and present the technical problems that arose from our experience. We describe our experience constructing sev...

Real-scale Semantic Web applications, such as Web Portals and E-Marketplaces, require the management of voluminous metadata repositories containing descriptive information (i.e., metadata) about the available Web resources and services. Better knowledge about the meaning, usage, accessibility or quality of these resources and services will considerably facilitate the automated processing of both Web content and services. In this context, the Resource Description Framework (RDF) enables the creation and exchange of metadata as any other Web data. Although large volumes of RDF descriptions are already appearing (e.g., as exported Portal catalogs or service descriptions), sufficiently expressive declarative languages for querying both RDF descriptions and schemas are still missing. In this paper, we propose RQL, a new RDF query language, relying on a formal graph model that permits the interpretation of superimposed resource descriptions. RQL is an OQL-inspired adaptation of XML query languages to the peculiarities of RDF but, foremost, is an extension of this functionality for uniformly querying both descriptions and schemas. We illustrate the syntax, semantics and core functionality of RQL bymeans of a set of benchmark queries and report on the performance of RSSDB, our persistent RDF Store, for storing and querying voluminous RDF descriptions.

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We describe a tool for compressing XML data, with applications in data exchange and archiving, which usually achieves about twice the compression ratio of gzip at roughly the same speed. The compressor, called XMill, incorporates and combines existing compressors in order to apply them to heterogeneous XML data: it uses zlib, the library function for gzip, a collection of datatype specific compressors for simple data types, and, possibly, user defined compressors for application specific data types. 1 Introduction We have implemented a compressor/decompressor for XML data, to be used in data exchange and archiving, that achieves about twice the compression rate of general-purpose compressors (gzip), at about the same speed. The tool can be downloaded from www.research.att.com/sw/tools/xmill/. XML is now being adopted by many organizations and industry groups, like the healthcare, banking, chemical, and telecommunications industries. The attraction in XML is that it is a self-describi...

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Keywords. Data exchange, XML, Relational databases, XML Queries. XML is the standard format for data exchange between inter-enterprise applications on the Internet. To facilitate data exchange, industry groups dene public document type denitions (DTDs) that specify the format of the XML data to be exchanged between their applications. In this paper, we address the problem of automating the conversion of relational data into XML. We describe SilkRoute, a general, dynamic, and ecient tool for viewing and querying relational data in XML. SilkRoute is general, because it can express mappings of relational data into XML that conforms to arbitrary DTDs, not just a canonical mapping of the relational schema. We call these mappings views. Applications express the data they need as an XML-QL query over the view. SilkRoute is dynamic, because it only materializes the fragment of an XML view needed by an application, and it is ecient, because it fully exploits the underlying RDBMs que...

We study the inference of Data Type Definitions (DTDs) for views of XML data, using an abstraction that focuses on document content structure. The views are defined by a query language that produces a list of documents selected from one or more input sources. The selection conditions involve vertical and horizontal navigation, thus querying explicitly the order present in input documents. We point several strong limitations in the descriptive ability of current DTDs and the need for extending them with (i) a subtyping mechanism and (ii) a more powerful specification mechanism than regular languages, such as context-free languages. With these extensions, we show that one can always infer tight DTDs, that precisely characterize a selection view on sources satisfying given DTDs. We also show important special cases where one can infer a tight DTD without requiring extension (ii). Finally we consider related problems such as verifying conformance of a view definition with a predefined DTD....

time provides more structure than the plain semistructured model of existing approaches like TSIMMIS. Given the central role of DTDs in our approach, #semi-#automatic inference of view DTDs becomes an important issue. The DTD inference task is to infer the DTDs of the mediator view, given the mediator view de#nition and the source DTDs; see #PV99# for an algorithm on Mix's DTD inference. The novel features of the Mix system include: # Data exchange and integration solely relies on XML, i.e., instance and schema information is represented by XML documents and XML DTDs, respectively. # XML queries are denoted in a high-level, declarative query language Xmas 1 , which builds upon ideas of languages like XML-QL, Yat, MSL, and UnQL #XML98, CDSS98, PAGM96, BDFS97#. For example, Xmas allows object fusion and pattern matching on the input XML data. Additionally, Xmas features powerful