Databases Reference
In-Depth Information
Table 5.1 XML standards. Application portability between native XML systems is highly sensitive to the
standards each database implements. Note that not all standards are published by the W3C.
Standards
organization
Standard name
Description
Extensible
Markup
Language (XML)
W3C
The XML standard specifies how tree-structured data is stored in a
text file using elements and attributes. The standard has precise
information about what character sets are used, how special charac-
ters are escaped, and any special processing instructions that might
be used by an application. Unlike JSON, XML supports multiple
namespaces and mixed content.
XPath
W3C
The XPath specification describes how to select a subset of an XML
file using simple path expressions. Path expressions are steps into a
part of the document or complex expressions with conditional state-
ments and loops. XPath is a building block specification that's used
in other XML specifications including XSLT, XQuery, Schematron,
XForms, and XProc.
XML Schema
W3C
XML schemas are XML files used to quickly validate the structure of
an XML document in a single pass and check the format rules of
each leaf element. XML schemas are designed so that validation on
large documents occurs quickly. XML Schema 1.1 has added new fea-
tures that allow XPath expressions to be used to validate documents.
XML Schema is a mature standard and is supported by graphical
design tools.
XQuery
W3C
XQuery is a W3C standard for querying XML files and XML databases.
XQuery is considered a functional programming language and is built
around a parallel programming construct called a FLWOR statement
that can be easily executed on multiple processors.
XQuery/XPath
full-text Search
W3C
The W3C full-text search standard specifies how full-text searches
should be implemented in any XQuery or XPath engine.
Schematron
ISO/IEC
Schematron is a rule-based validation language for making asser-
tions about the presence or absence of patterns in XML trees. Unlike
XML Schema, Schematron allows you to express if/then rules in
XPath that can apply to any node in an XML document. A rule about
the last node in a large file may reference an element in the first node
of the file, so the entire file may need to be in memory to validate the
rules.
XProc
W3C
XProc is a W3C XML declarative language for pipeline processing of
documents. Typical steps might include expanding includes, validat-
ing, splitting documents, joining documents, transforming, and stor-
ing documents. XProc leverages other XML standards including
XPath.
XForms
W3C
XForms is a W3C XML declarative language standard for building cli-
ent applications that use a model-view-controller (MVC) architecture.
It has the ability to create complex web applications without using
JavaScript.
