XML Information Set (XML Infoset) is a
W3C specification describing an abstract data model of an
XML
Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable ...
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 A well-formed document in XML is a document that "adheres to the syntax rules specified by the XML 1.0 specification in that it must satisfy both physical and logical structures".
Requirements
At its base level well-formed documents require that:
...
.
An XML document has an information set if it is
well-formed and satisfies the
namespace
In computing, a namespace is a set of signs (''names'') that are used to identify and refer to objects of various kinds. A namespace ensures that all of a given set of objects have unique names so that they can be easily identified.
Namespaces ...
constraints. There is no requirement for an XML document to be
valid 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
In computing, a namespace is a set of signs (''names'') that are used to identify and refer to objects of various kinds. A namespace ensures that all of a given set of objects have unique names so that they can be easily identified.
Namespaces ...
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
The word schema comes from the Greek word ('), which means ''shape'', or more generally, ''plan''. The plural is ('). In English, both ''schemas'' and ''schemata'' are used as plural forms.
Schema may refer to:
Science and technology
* SCHEMA ...
validation, for example by adding default attributes. The augmented infoset is called the post-schema-validation infoset, or
PSVI
XSD (XML Schema Definition), a recommendation of the World Wide Web Consortium ( W3C), specifies how to formally describe the elements in an Extensible Markup Language (XML) document. It can be used by programmers to verify each piece of item con ...
.
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
An XML schema is a description of a type of XML document, typically expressed in terms of constraints on the structure and content of documents of that type, above and beyond the basic syntactical constraints imposed by XML itself. These constra ...
but not
RELAX NG
In computing, RELAX NG (REgular LAnguage for XML Next Generation) is a schema language for XML—a RELAX NG schema specifies a pattern for the structure and content of an XML document. A RELAX NG schema is itself an XML document but RELAX NG also ...
.
Serialization
Typically, XML Information Set is serialized as XML. There are also serialization formats for
Binary XML
Various binary formats have been proposed as compact representations for XML (''Extensible Markup Language''). Using a binary XML format generally reduces the verbosity of XML documents thereby also reducing the cost of parsing, but hinders the use ...
,
CSV, and
JSON.
Apache CXF JSON Support
/ref>
See also
XML Information Set instances:
* Document Object Model
The Document Object Model (DOM) is a cross-platform and language-independent interface that treats an XML or HTML document as a tree structure wherein each node is an object representing a part of the document. The DOM represents a document wi ...
* Xpath data model
The XQuery and XPath Data Model (XDM) is the data model shared by the XPath 2.0, XSLT 2.0, XQuery, and XForms programming languages. It is defined in a W3C recommendation.Anders Berglund, ''et al.''XQuery 1.0 and XPath 2.0 Data Model W3C, 2010, r ...
* SXML
References
External links
*
World Wide Web Consortium standards
XML-based standards
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