XML Information Set (XML Infoset) is a
W3C specification describing an abstract data model of an
XML document in terms of a set of ''information items''. The definitions in the XML Information Set specification are meant to be used in ''other'' specifications that need to refer to the information in a
well-formed XML document.
An XML document has an information set if it is
well-formed and satisfies the
namespace constraints. There is no requirement for an XML document to be
valid
Validity or Valid may refer to:
Science/mathematics/statistics:
* Validity (logic), a property of a logical argument
* Scientific:
** Internal validity, the validity of causal inferences within scientific studies, usually based on experiments
** ...
in order to have an information set.
An information set can contain up to eleven different types of information items:
#The Document Information Item (always present)
#Element Information Items
#Attribute Information Items
#
Processing Instruction Information Items
#Unexpanded Entity Reference Information Items
#Character Information Items
#Comment Information Items
#The Document Type Declaration Information Item
#Unparsed Entity Information Items
#Notation Information Items
#
Namespace Information Items
XML was initially developed without a formal definition of its infoset. This was only formalised by later work beginning in 1999, first published as a separate W3C Working Draft at the end of December that year.
Infoset recommendation Second Edition was adopted on 4 February, 2004. If a 2.0 version of the XML standard is ever published, it is likely that this would absorb the Infoset recommendation as an integral part of that standard.
Infoset augmentation
Infoset augmentation or infoset modification refers to the process of modifying the infoset during
schema validation, for example by adding default attributes. The augmented infoset is called the post-schema-validation infoset, or
PSVI.
Infoset augmentation is somewhat controversial, with claims that it is a violation of modularity and tends to cause interoperability problems, since applications get different information depending on whether or not validation has been performed.
Infoset augmentation is supported by
XML Schema but not
RELAX NG.
Serialization
Typically, XML Information Set is serialized as XML. There are also serialization formats for
Binary XML,
CSV, and
JSON
JSON (JavaScript Object Notation, pronounced ; also ) is an open standard file format and data interchange format that uses human-readable text to store and transmit data objects consisting of attribute–value pairs and arrays (or other ser ...
.
Apache CXF JSON Support
/ref>
See also
XML Information Set instances:
* Document Object Model
* Xpath data model
* SXML
SXML is an alternative syntax for writing XML data (more precisely, XML Infosets) as S-expressions, to facilitate working with XML data in Lisp and Scheme. An associated suite of tools implements XPath, SAX and XSLT for SXML in Scheme and are ava ...
References
External links
*
World Wide Web Consortium standards
XML-based standards
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