[...]... The processing context of an XML document A physical structure with three entities A schema with an anonymous complex type definition A schema with a named complex type definition A schema with references to global elements A schema with an attribute declaration XML document as a tree 25 34 56 56 57 59 64 Fig 3.1 Fig 3.2 Fig 3.3 Levels of XML standardization The... systems with front-ends for users to work with documents Others, such as Software AG’s Tamino XML Server, provide software packages intended for building applications to manage XML data In the second form of repository, a relational or object-oriented database system is extended to support XML data All current commercial database systems provide some XML support, including Oracle’s XML DB, IBM’s DB2 pureXML,... uses of XML This chapter describes XML in more detail and how it is processed by computers Like HTML, the unit of communication when using XML is a document The abbreviation XML comes from the name Extensible Markup Language XML was developed initially for representing information in the context of the Internet When using XML, software applications store and exchange data in the form of documents Within... Applications of XML for metadata storage and management is described in Sect 1.5.3 and elaborated in Chap 6 12 1 Setting the Stage Finally, XML is also used to transmit data among diverse Internet applications If an application stores its data in XML form, it can easily ship it out or receive new fragments of XML data However, even programs that do not store their data and metadata as XML have adopted XML as... entities and characters 36 49 Table 3.1 Table 3.2 Table 3.3 Table 3.4 Table 3.5 Table 3.6 Table 3.7 XML accessories XML transducers XML applications for Web publishing XML applications for metadata and Semantic Web XML applications for Web communication and services XML applications for non-textual data Government interoperability frameworks 75 76 79 80 82 83... structured and presented within that domain Development of new solutions is often a challenging collaborative effort involving people with varying backgrounds and expertise In this chapter we will show why XML evolved, what is special about XML as compared to earlier ways to present digital information, and what kinds of capabilities it offers We introduce the core concepts of XML without going into detail... elements XML is a restricted form of SGML,1 an older markup language The rules constraining all XML documents are defined in XML specifications published by the World Wide Web Consortium (W3C) as W3C Recommendations [23] 1 SGML, the Standard Generalized Markup Language, was accepted as ISO standard 8879 in 1986 [16] and later augmented by supplements [17] A Salminen and F Tompa, Communicating with XML, DOI... DB, IBM’s DB2 pureXML, and Microsoft’s SQLXML When conventional database systems were first used for XML, the data model of the original system was typically extended to encompass XML data, but the extensions defined simplified tree models rather than rich XML documents More recently, however, relational database vendors have developed extensions that encompass XML more fully In some approaches, whole... special table, can be associated with XML documents and used to validate them 1.5.2 Other Primary Data XML databases are used for storing not only documents but also other kinds of data Simple data types, such as numerics, logical values, dates, and times, may be declared in a schema language such as XML Schema, and stored in documents as simply as storing text strings In fact, XML Schema defines a hierarchy... processing models for XML, one based on streams and one based on trees, are introduced Although not all details of XML are covered, the chapter provides some literacy with respect to XML specifications, so that the complete language can be learned as necessary Keywords DTD • Formal grammars • Logical structure • Namespaces • Physical structure • Processing models • RELAX NG • Schema languages • XML documents .