Cobweb: Constrained XML for the Web

Sigmod Record, 2009

XML has conquered its place as the most used standard for representing Web data. An XML schema may be employed for similar purposes of those from database schemas. There are different languages to write an XML schema, such as DTD and XSD. In this paper, we provide a general view, an X-Ray, on Web-available XSD files by identifying which XSD constructs are more and less frequently used. Furthermore, we provide an evolution perspective, showing results from XSD files collected in 2005 and 2008. Hence, we can also draw some conclusions on what trends seem to exist in XSD usage. The results of such study provide relevant information for developers of XML applications, tools and algorithms in which the schema has a distinguished role.

Proceedings of the International Conference on …, 2000

The amount of useful semi-structured data on the web continues to grow at a stunning pace. Often interesting web data are not in database systems but in HTML pages, XML pages, or text les. Data in these formats is not directly usable by standard SQL-like query processing ...

Proceedings of the 2006 ACM symposium on …, 2006

StandardView, 1998

2004

Abstract In the past few years, a number of constraint languages for XML documents has been proposed. They are cumulatively called schema languages or validation languages and they comprise, among others, DTD, XML Schema, RELAX NG, Schematron, DSD, xlinkit. One major point of discrimination among schema languages is the support of co-constraints, or co-occurrence constraints, eg, requiring that attribute A is present if and only if attribute B is (or is not) presentin the same element.

2007

XML Schema supports the specification of occurrence constraints by declaring values for its min/max Occurs attributes. These constraints are structural in the sense that they restrict the cardinality of children elements independently of the data that is present in their subtrees. Thus, occurrence constraints do not address any data semantics and are therefore only of limited interest to data modelling.

Dke, 2007

XML has evolved as the new standard for the representation and exchange of both structured and semistructured data. XML's ability to succinctly describe complex information can also be used for specifying application meta-data. XML's popularity is evident from its use in a wide spectrum of application domains: from document publication, to computational chemistry, health care and life sciences, multimedia and ecommerce. Increasing popularity of web-based business and the emergence of web services that use XML-based descriptions in WSDL and exchange XML messages with SOAP have led to further acceptance of XML. The purpose of the second XML Data and Schema Management Workshop was to provide a forum for the exchange of ideas and experiences among the theoreticians and practitioners who are involved in design, management, and implementation of XML data management systems. It was held on 3 April, 2005 in conjunction with the 21st IEEE International Conference on Data Engineering (ICDE 2005). The workshop saw a lengthy full-day program that included 12 regular papers divided into three sessions. Many interesting discussions sparked off during the workshop among the presenters and the audience in almost any XML data management topics. This special issue of Data and Knowledge Engineering features four papers selected from the XSDM 2005 workshop based on their merits and relevance. Each of these papers is an extended and revised version of the original workshop paper and has gone through a rigorous reviewing process before being accepted for inclusion in this special issue. In the first paper entitled ''QMatch-A Hybrid Match Algorithm for XML Schemas'', Tansalarak and Claypool propose a new hybrid schema match algorithm, QMatch, that provides a unique path-based framework for harnessing traditional structural and semantic information, while exploiting the constraints inherent in XML documents such as the order of XML elements, to provide improved levels of matching between two given XML schemata. QMatch is based on the measurement of a unique quality of match metric, QoM, and a set of classifiers. They experimentally demonstrated the benefits of QMatch over existing algorithms such as Cupid. Efficient processing of XML queries is a key area of research in XML data management. The next two papers thus focus of efficient XML query evaluation. Chen et al. in their paper titled ''Index Structures for Matching XML Twigs Using Relational Query Processors'' address some of the limitations of existing XML path indices. They present a framework defining a family of index structures that includes most existing XML path indices. They also propose two novel index structures with different space-time tradeoffs effective for the evaluation of XML twig queries with value conditions. They also show how this family of index structures can be tightly integrated with a relational query processor. The next paper entitled ''Optimization of Nested XQuery Expressions with Orderby Clauses'' by Wang, Rundensteiner, and Mani, presents a technique for XQuery optimization. They propose an algebraic rewriting technique of nested XQuery expressions containing explicit ORDERBY clauses. Their technique is based on

CLEI Electronic Journal, 2018

After being able to mark-up text and validate its structure according to a document type specification, we may start thinking it would be natural to be able to validate some non- structural issues in the documents. This paper is to formally discuss semantic-related aspects. In that context, we introduce a domain specific language developed for such a purpose: XCSL. XCSL is not just a language, it is also a processing model. Furthermore, we discuss the general philosophy underlying the proposed approach, presenting the architecture of our semantic vali- dation system, and we detail the respective processor. To illustrate the use of XCSL language and the subsequent processing, we present two case-studies. Nowadays, we can find some other languages to restrict XML documents to those semantically valid — namely Schematron and XML-Schema. So, before concluding the paper, we compare XCSL to those approaches.

2004

International Journal of Advanced Corporate Learning (iJAC), 2010

Database normalization is a process which eliminates redundancy, organizes data efficiently and improves data consistency. Functional, multivalued, and join dependencies (FDs, MVDs, and JDs) play fundamental roles in relational databases where they provide semantics for the data and at the same time are the foundations for database design. In this study we investigate the issue of defining functional, multivalued and join dependencies and their normal forms in XML database model. We show that, like relational databases, XML documents may contain redundant information, and this redundancy may cause update anomalies. Furthermore, such problems are caused by certain dependencies among paths in the document. Our goal is to find a way for converting an arbitrary XML Schema to a well-designed one that avoids these problems. We extend the notion of tuple for relational databases to the XML model. We show that an XML tree can be represented as a set of tree tuples. We introduce the definiti...