Method for linking XML documents together
XML Linking Language
, or
XLink
, is an
XML
markup language
and
W3C
specification that provides methods for creating internal and external links within XML documents, and associating metadata with those links.
[1]
The XLink specification
[
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]
XLink 1.1 is a W3C recommendation
[2]
and the successor of XLink 1.0, which was also a W3C recommendation.
[3]
[4]
Linking with XLink
[
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]
XLink defines a set of
attributes
that may be added to elements of other
XML namespaces
. XLink provides two kinds of hyperlinking for use in XML documents.
Simple links
connect only two resources, similar to
HTML
links.
Extended links
can link an arbitrary number of resources.
Simple links
[
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]
A
simple link
creates a unidirectional
hyperlink
from one element to another via a
URI
. Example:
<?xml version="1.0"?>
<document
xmlns=
"http://example.org/xmlns/2002/document"
xmlns:xlink=
"http://www.w3.org/1999/xlink"
>
<heading
id=
"someHeading"
>
Some
Document
</heading>
<para>
Here
is
<anchor
xlink:type=
"simple"
xlink:href=
"#someHeading"
>
a
link
</anchor>
to
the
header.
</para>
<para>
It
is
an
anchor
that
points
to
the
element
with
the
id
"someHeading"
on
the
current
page.
</para>
</document>
Extended links
[
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]
Extended links
allow multiple resources, either remote or local, to be connected by multiple arcs. An
arc
is information about the origin, destination and behavior of a link between two resources. The origin and destination resources are defined by labels. By using one or more arcs, an extended link can achieve specific sets of connections between multiple resources.
For example, if all resources in an extended link were given the label
A
, then an arc within that link declaring
from="
A
", to="
A
"
would form connections between all resources.
Extended links do not need to be contained in the same document as the elements they link to. This makes it possible to associate metadata or other supplementary information with resources without editing those resources.
XLink also supports richer information about link types and the roles of each resource in an arc.
Support for XLink
[
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]
Within other specifications
[
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]
Hypertext links in
Scalable Vector Graphics
can currently be defined as simple XLinks.
[5]
The
working draft
of SVG 1.2 proposes using extended XLinks as well.
[6]
In the SVG 2 specification, XLink was deprecated in favor of non-namespaced equivalent attributes.
[7]
RDDL
[
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]
The
Resource Directory Description Language
, an extension to
XHTML Basic
that is used to describe
XML Namespaces
, uses simple XLinks.
[8]
XBRL
[
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]
The
eXtensible Business Reporting Language
has used simple and extended XLinks since the XBRL 2.0 specification was published in 2001.
[9]
Most large XBRL taxonomies contain extensive linkbases. As of 2009, XBRL is probably the most extensive use of XLink in production systems.
METS
[
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]
The
Metadata Encoding and Transmission Standard
, supported and maintained by the
Library of Congress
for describing file aggregations, uses simple XLinks in pointing to file locations as well as linkbases which describe relationships among external files (though these restrict
to
and
from
attributes to type IDREF instead of NMTOKEN).
[10]
[11]
Geography Markup Language
uses simple XLinks to implement referencing. In particular, GML uses xlink:href to support a graph model for geospatial information. GML's graph model is essentially the same as
RDF
, on which early versions of GML were based. The GML specification constrains the semantics of XLinks to be essentially the same as rdf:resource (from the RDF/XML syntax) i.e. the referent can logically be placed in-line and the data is still valid.
Implementations
[
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]
Mozilla Firefox
[
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]
Mozilla Firefox
has supported simple XLinks since version 1.5, but only for
SVG
and
MathML
documents. It is unsupported in other XML documents.
[12]
Only the
xlink:href
,
xlink:show
,
xlink:target
and
xlink:title
attributes are supported.
[13]
Prince
[
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]
Prince
supports simple XLinks.
[14]
References
[
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]
- ^
DeRose, Steven J. (1999-02-24),
XML XLink Requirements
, W3C
- ^
XML Linking Language (XLink) Version 1.1
, W3C, May 6, 2010
- ^
XML Linking Language (XLink) Version 1.0
, W3C, June 8, 2006
- ^
"XML and Semantic Web W3C Standards Timeline"
(PDF)
.
- ^
Scalable Vector Graphics (SVG) 1.1 Specification: Linking
, W3C, June 8, 2006
- ^
Extended Links (SVG 1.2)
, W3C, June 8, 2006
- ^
"Linking ? SVG 2"
.
www.w3.org
. Retrieved
2016-09-18
.
- ^
Borden, Jonathan; Bray, Tim (2002-02-18),
Resource Directory Description Language (RDDL)
, The Open Healthcare Group, Antarcti.ca Systems
- ^
Extensible Business Reporting Language (XBRL) 2.1 - XLink in XBRL
, XBRL International Inc.
- ^
METS: An Overview & Tutorial
, Library of Congress
- ^
Metadata Encoding and Transmission Standard: Primer and Reference Manual
(PDF)
, Library of Congress, September 2007, p. 133
- ^
XLink - MDC
, Mozilla, archived from
the original
on 2012-04-06
, retrieved
2010-02-19
- ^
SVG in Firefox
, Mozilla, archived from
the original
on 2008-08-29
, retrieved
2010-02-19
- ^
Prince: XML Input
, YesLogic
External links
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Products and
standards
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Organizations
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Community & business groups
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Closed groups
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Software
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Conferences
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Basics
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Resource identifiers
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Concepts
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Technology
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See also
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