XML Information Set
Encyclopedia
XML Information Set 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
in order to have an information set.
An information set can contain up to eleven different types of information items:
Infoset recommendation Second Edition was adopted on February 4, 2004.
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
.
W3C recommendation
A W3C Recommendation is the final stage of a ratification process of the World Wide Web Consortium working group concerning a technical standard. This designation signifies that a document has been subjected to a public and W3C-member organization's review. It aims to standardise the Web technology...
describing an abstract data model of an XML
XML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
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
XML Namespace
xmlns tagged XML namespaces are used for providing uniquely named elements and attributes in an XML document. They are defined in a W3C recommendation. An XML instance may contain element or attribute names from more than one XML vocabulary...
constraints. There is no requirement for an XML document to be valid
Valid XML document
A valid XML document is defined by the W3C as a well-formed XML document which also conforms to the rules of a Document Type Definition or an XML Schema , which W3C supports as an alternate to DTD....
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
Infoset recommendation Second Edition was adopted on February 4, 2004.
Infoset Augmentation
Infoset augmentation or infoset modification refers to the process of modifying the infoset during schemaXML 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...
validation, for example by adding default attributes. The augmented infoset is called the post-schema-validation infoset, or PSVI
PSVI
PSVI is an acronym for Post-Schema-Validation Infoset, a term used in XML parsing. It is the extended infoset after the XML instance has been validated against the attached schema document and extends the XML infoset after validation. Briefly, an XML schema assigns an identifiable type to each...
.
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
RELAX NG
In computing, RELAX NG is a schema language for XML, based on Murata Makoto's RELAX and James Clark's TREX. A RELAX NG schema specifies a pattern for the structure and content of an XML document...
.
See also
XML Information Set instances:- Document Object ModelDocument Object ModelThe Document Object Model is a cross-platform and language-independent convention for representing and interacting with objects in HTML, XHTML and XML documents. Aspects of the DOM may be addressed and manipulated within the syntax of the programming language in use...
- Xpath data modelXpath data modelXPath is a language for selecting portions of an XML Document . XPath uses a specific conceptual interpretation of XML documents, referred to as the XPath Data Model. Technical documents on XML often use the same terminology as the XPath data model....
- SXMLSXMLSXML is a way to write and process XML data in the form of S-expressions.Textual correspondence between SXML and XML for a sample XML snippet is shown below: XML SXML Text node SXML is a way to write and process XML data in the form of S-expressions.Textual correspondence between...
External links
- Fastinfoset (for binary encoding of the Infoset)