XML schema support in MXquery
Kostis Tsoulos · 2008
XQuery, a powerful query language for querying XML data, and XML Schema, a language for expressing a schema-a set of rules describing the structure and data content of XML documents- are established XML technologies and W3C standards. The W3C Recommendation for XQuery describes the option of using and importing XML schemas in XQuery queries, allowing for the assignment of types to data and validation of both input XML and query results. The feature of schema-awareness provides the XQuery processor with information about definitions included in schemas, resulting in better optimized and tested queries. This information can be exploited to facilitate and support predictability, early detection of errors, optimizations, special processing based on type and the validity of query results. At the same time, data stream processing has become a hot topic. One of the issues that the research community tries to resolve is the fact that streaming is dealing-by its very nature- with infinite data sources and in most cases a streamed element can be seen and accessed only once. A recent research proposal provides a formal specification of schema for describing the properties of