Susan Malaika

The WS-DAI family of specifications for web service data access and integration

This month, we are pleased to provide to our readers a column that addresses an important aspect of grid computing: data access.

Preserving XML queries during schema evolution

In XML databases, new schema versions may be released as frequently as once every two weeks. This poster describes a taxonomy of changes for XML schema evolution. It examines the impact of those changes on schema validation and query evaluation. Based on that study, it proposes guidelines for XML schema evolution and for writing queries in such a way that they continue to operate as expected across evolving schemas.

Standards for databases on the grid

Relational databases supported applications in a centralized environment in the 1960s and 1970s. They progressed to a client/server environment in the 1980s. The 1990s saw application servers with a multi-tiered architecture, in most cases supported by an RDBMS. Most recently we have seen the emergence of XML, XML storage in DBMSs, navigation within an XML document via XPath, and the XQuery query language for XML. In this article, Susan provides an introduction to the Grid and describes how databases will be used in this new environment. The Global Grid Forum (GGF) is producing technical specification to enable both Relational and XML databases to be located, accessed, and replicated in this environment. They make use of a variety of existing an emerging database, file, networking, and web services standards. Susan is a Senior Technical Staff Member at IBM. She is a member of the GGF DAIS (Data Access and Integration Services) working group. Jim Melton and Andrew Eisenberg

Towards an information infrastructure for the grid

In this paper we present our vision of an information infrastructure for grid computing, which is based on a service-oriented architecture. The infrastructure supports a virtualized view of the computing and data resources, is autonomic (driven by policies) in order to meet application goals for quality of service, and is compatible with the standards being developed in the technical community. We describe how we are implementing this vision in IBM today and how we expect the implementation to evolve in the future.

Virtual XML: a toolbox and use cases for the XML world view

Although the Extensible Markup Language (XML) has gained in popularity and has resulted in the creation of powerful software for authoring, transforming, and querying XML-based business data, much information remains in non-XML form. In this paper we introduce an approach to virtualize data resources and thus enable applications to access both XML and non-XML sources. We describe the architectural components that enable virtual XML-a toolbox that includes a cursor model, an XML-view mechanism such as the view created with the Data Format Description Language (DFDL), and XML processing languages. We illustrate the applicability of virtual XML through a number of use cases in various environments. We discuss the products that we expect from vendors and the open-source community and the way enterprises can plan to take advantage of virtual XML developments. Finally, we outline future research directions that include a vision of virtual XML that covers large-scale structures such as entire file systems, databases, or even the World Wide Web.

Using XML in relational database applications

The author reviews relational database XML features and describes their use in database applications. Aspects that will be considered include the creation, validation, transformation, storage and retrieval of XML documents, the inclusion of existing and new relational data in XML documents, and the impact of XML Links.

Entity matching for semistructured data in the Cloud

The rapid expansion of available information, on the Web or inside companies, is increasing. With Cloud infrastructure maturing (including tools for parallel data processing, text analytics, clustering, etc.), there is more interest in integrating data to produce higher-value content. New challenges, notably include entity matching over large volumes of heterogeneous data. In this paper, we describe an approach for entity matching over large amounts of semistructured data in the Cloud. The approach combines ChuQL[4], a recently proposed extension of XQuery with MapReduce, and a blocking technique for entity matching which can be efficiently executed on top of MapReduce. We illustrate the proposed approach by applying it to extract automatically and enrich references in Wikipedia and report on an experimental evaluation of the approach.

Comparing XML processing performance in middleware and database: a case study

XML processing is at the core of many middleware systems. In recent years XML databases have become widely available. This article identifies three common XML processing use cases, and compares their performance when XML manipulation is performed in an XML database with equivalent XML manipulation implemented through middleware application code. The article concludes with guidelines for XML processing placement and identifies areas for further study.

Universal XForms for Dynamic XQuery Generation

This demonstration illustrates how a variety of queries can be built dynamically by examining XML stored in databases through general purpose XForms. The forms are called the Universal XForms for XQuery, and abbreviated to the Universal XForms. The Universal XForms help users to construct XQueries through the provision of prompts, and do not require prior knowledge of the structure of the data to be queried. Sample XML documents from more than twenty industry formats constitute the base for illustrating the building of queries in the demonstration.