Australian Government Architecture Reference Models Version 3.0

Term Definition
eXtensible Markup
Language (XML) [top]
Extensible Markup Language has at least two distinct meanings: (1) a set of
generic syntax rules to enable the creation of specialised markup languages
that follow similar conventions; and (2) an ever-growing collection of standard,
de facto standard and special purpose languages based on XML syntax (e.g.
XSLT, UBL, ebXML, XML Schema, XHTML, RDF, OWL, SVG, etc.).
Sometimes the term ‘XML’ is used incorrectly when ‘XML Schema’ is actually
intended. (More: W3C XML home page)
XML Document [top] A storage unit (i.e. a file) containing XML markup and content. (DRM usage)
XML Registries and
Repositories [top]
A data object is an XML document if it is well-formed as defined in this
specification. A well-formed XML document may, in addition, be valid if it meets
certain further constraints. (XML 1.0 Recommendation, Third Edition)
An information system that securely stores XML artefacts (e.g. XML schemas,
data elements, etc.) and non-XML artefacts (e.g. other e-business objects), as
well as details (metadata) about the artefacts. The storage facility (e.g. a file
system or database) that holds registered objects is known as a repository,
while the part of the information system that maintains the metadata for the
registered objects is known as a registry (ebXML document).
XML Schema [top] Defines the vocabulary (elements and attributes), the content model (structure,
element nesting and text content) and data types (value constraints) of a class
of XML documents. When written with a capital 'S', the term refers specifically
to the XML Schema Definition (XSD or WXS) language developed by the W3C.
However, when written with a lower case 's', the meaning is more generic,
referring to any of several schema languages for use with XML, such as DTDs,
RELAX NG, Schematron, etc. In both cases, an XML schema is used to
validate XML instances to verify that the instances conform to the model that
the schema describes.
XML Path Language
(XPath) [top]
A terse non-XML syntax for addressing portions of an XML document. A path
expression is written as a sequence of steps to get from one set of nodes to
another set of nodes. XPath also allows more conventional expressions,
involving arithmetic and Boolean operators and a range of functions to perform
string manipulation, etc.
XML Query (XQuery) [top] A query language with some programming language features designed to
query collections of XML data. It is semantically similar to SQL and is being
developed by the XML Query working group of the W3C. The work is closely
coordinated with the development of XSLT 2.0 by the XSL Working Group; the
two groups share responsibility for XPath 2.0, which is a subset of XQuery 1.0.
At the time of writing, XQuery is a W3C Candidate Recommendation, although
dozens of implementations are available in various states of completeness. In
addition to XPath addressing, it provides SQL-like FLWOR expressions based
on five possible clauses: FOR, LET, WHERE, ORDER BY, RETURN.
Note: XQuery 1.0 does not include features for updating XML documents or
databases. It also lacks full text search capability. These features are both
under active development for a subsequent version of the language. (More:
W3C XML Query page)
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