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Extensible Markup Language
File extension: .xml
MIME type: application/xml, text/xml (deprecated)
Uniform Type Identifier: public.xml
Developed by: World Wide Web Consortium
Type of format: Markup language
Extended from: SGML
Extended to: XHTML, RSS, Atom, ...
Standard(s): 1.0 (Fourth Edition) 1.1 (Second Edition)

The Extensible Markup Language (XML) is a general-purpose markup language.[1] It is classified as an extensible language because it allows its users to define their own tags. Its primary purpose is to facilitate the sharing of structured data across different information systems, particularly via the Internet.[2] It is used both to encode documents and serialize data. In the latter context, it is comparable with other text-based serialization languages such as JSON and YAML.[3] Image File history File links XML.svg‎ This is a graphical depiction of a very simple xml file. ... A filename extension is a suffix to the name of a computer file applied to show its format. ... For mime as an art form, see mime artist. ... A Uniform Type Identifier (UTI) is a string that uniquely identifies the type of a class of items. ... It has been suggested that W3C Markup Validation Service be merged into this article or section. ... A specialized markup language using SGML is used to write the electronic version of the Oxford English Dictionary. ... The Standard Generalized Markup Language (SGML) is a metalanguage in which one can define markup languages for documents. ... The Extensible HyperText Markup Language, or XHTML, is a markup language that has the same depth of expression as HTML, but also conforms to XML syntax. ... For other meanings of RSS, see RSS (disambiguation). ... The name Atom applies to a pair of related standards. ... Standards are produced by many organizations, some for internal usage only, others for use by a groups of people, groups of companies, or a subsection of an industry. ... A specialized markup language using SGML is used to write the electronic version of the Oxford English Dictionary. ... An extensible language is any high-level language that allows its user to modify or enrich its syntax in such a way that a person that does not know the base code cannot tell the customized content from the original. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In computer science, in the context of data storage and transmission, serialization is the process of saving an object onto a storage medium (such as a file, or a memory buffer) or to transmit it across a network connection link, either in binary form, or in some human-readable text... JSON (JavaScript Object Notation) (Pronounced like Jason, IPA ) is a lightweight computer data interchange format. ... YAML (Rhymes with camel) (IPA pronunciation: ) is a human-readable data serialization format that takes concepts from languages such as XML, C, Python, Perl, as well as the format for electronic mail as specified by RFC 2822. ...


It started as a simplified subset of the Standard Generalized Markup Language (SGML), and is designed to be relatively human-legible. By adding semantic constraints, application languages can be implemented in XML. These include XHTML,[4] RSS, MathML, GraphML, Scalable Vector Graphics, MusicXML, and thousands of others. Moreover, XML is sometimes used as the specification language for such application languages. The Standard Generalized Markup Language (SGML) is a metalanguage in which one can define markup languages for documents. ... The Extensible HyperText Markup Language, or XHTML, is a markup language that has the same depth of expression as HTML, but also conforms to XML syntax. ... For RSS feeds from Wikipedia, see Wikipedia:Syndication. ... Mathematical Markup Language (MathML) is an application of XML for describing mathematical notation and capturing both its structure and content. ... There are very few or no other articles that link to this one. ... SVG redirects here. ... MusicXML is an open, XML-based music notation file format. ... A specification language is a formal language used in computer science. ...


XML is recommended by the World Wide Web Consortium. It is a fee-free open standard. The W3C recommendation specifies both the lexical grammar, and the requirements for parsing. A W3C Recommendation is the final stage of a ratification process of the W3C working group concerning the standard. ... It has been suggested that W3C Markup Validation Service be merged into this article or section. ... This article or section cites very few or no references or sources. ... In computer science a lexical grammar can be thought of as the syntax of tokens. ... An example of parsing a mathematical expression. ...

Contents

Well-formed and valid XML documents

There are two levels of correctness of an XML document:

  • Well-formed. A well-formed document conforms to all of XML's syntax rules. For example, if an element has an opening tag with no closing tag and is not self-closing, it is not well-formed. A document that is not well-formed is not considered to be XML; a conforming parser is not allowed to process it.
  • Valid. A valid document additionally conforms to some semantic rules. These rules are either user-defined, or included as an XML schema or DTD. For example, if a document contains an undefined tag, then it is not valid; a validating parser is not allowed to process it.

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 syntax constraints imposed by XML itself. ... Document Type Definition (DTD), defined slightly differently within the XML and SGML (the language XML was derived from) specifications, is one of several SGML and XML schema languages, and is also the term used to describe a document or portion thereof that is authored in the DTD language. ...

Well-formed documents: XML syntax

As long as only well-formedness is required, XML is a generic framework for storing any amount of text or any data whose structure can be represented as a tree. The only indispensable syntactical requirement is that the document has exactly one root element (alternatively called the document element). This means that the text must be enclosed between a root opening tag and a corresponding closing tag. The following is a well-formed XML document:

 <book>This is a book.... </book> 

The root element can be preceded by an optional XML declaration. This element states what version of XML is in use (normally 1.0); it may also contain information about character encoding and external dependencies. A character encoding or character set (sometimes referred to as code page) consists of a code that pairs a sequence of characters from a given set with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the storage of text in computers... In computer science, coupling or dependency is the degree to which each program module relies on each one of the other modules. ...

 <?xml version="1.0" encoding="UTF-8"?> 

The specification requires that processors of XML support the pan-Unicode character encodings UTF-8 and UTF-16 (UTF-32 is not mandatory). The use of more limited encodings, such as those based on ISO/IEC 8859, is acknowledged and is widely used and supported. The Unicode Standard, Version 5. ... A character encoding or character set (sometimes referred to as code page) consists of a code that pairs a sequence of characters from a given set with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the storage of text in computers... UTF-8 (8-bit UCS/Unicode Transformation Format) is a variable-length character encoding for Unicode. ... In computing, UTF-16 is a variable-length (16 or 32 bits) character encoding. ... UTF-32 and UCS-4 are alternate names for a method of encoding Unicode characters, using the fixed amount of exactly 32 bits for each Unicode code point. ... ISO 8859, more formally ISO/IEC 8859, is a joint ISO and IEC standard for 8-bit character encodings for use by computers. ...


Comments can be placed anywhere in the tree, including in the text if the content of the element is text or #PCDATA.


XML comments start with <!-- and end with -->. Two dashes (--) may not appear anywhere in the text of the comment.

 <!-- This is a comment. --> 

In any meaningful application, additional markup is used to structure the contents of the XML document. The text enclosed by the root tags may contain an arbitrary number of XML elements. The basic syntax for one element is:

 <name attribute="value">content</name> 

Here, »content« is some text which may again contain XML elements. So, a generic XML document contains a tree-based data structure. Here is an example of a structured XML document: A simple example unordered tree In computer science, a tree is a widely-used data structure that emulates a tree structure with a set of linked nodes. ...

 <recipe name="bread" prep_time="5 mins" cook_time="3 hours"> <title>Basic bread</title> <ingredient amount="3" unit="cups">Flour</ingredient> <ingredient amount="0.25" unit="ounce">Yeast</ingredient> <ingredient amount="1.5" unit="cups" state="warm">Water</ingredient> <ingredient amount="1" unit="teaspoon">Salt</ingredient> <instructions> <step>Mix all ingredients together.</step> <step>Knead thoroughly.</step> <step>Cover with a cloth, and leave for one hour in warm room.</step> <step>Knead again.</step> <step>Place in a bread baking tin.</step> <step>Cover with a cloth, and leave for one hour in warm room.</step> <step>Bake in the oven at 350°F for 30 minutes.</step> </instructions> </recipe> 

Attribute values must always be quoted, using single or double quotes, and each attribute name should appear only once in any element. XML requires that elements be properly nested — elements may never overlap. For example, the code below is not well-formed XML, because the em and strong elements overlap: Look up em in Wiktionary, the free dictionary. ... Strength can mean: Physical strength of organisms means (especially the muscles of most metazoa) of locomotion and movement Strength of materials in physics, engineering and materials science Strength is a rap compilation presented by Asiatic Warriors The word strengths is one of the longest English words with one syllable. ...

 <!-- WRONG! NOT WELL-FORMED XML! --> <p>Normal <em>emphasized <strong>strong emphasized</em> strong</strong></p> 

XML provides special syntax for representing an element with empty content. Instead of writing a start tag followed immediately by an end tag, a document may contain an empty-element tag. An empty-element tag resembles a start tag but contains a slash just before the closing angle bracket. The following three examples are equivalent in XML:

 <foo></foo> <foo /> <foo/> 

An empty-element tag may contain attributes:

 <info author="John" genre="science-fiction" date="2009-Jan-01" /> 

Entity references

'''An entity in XML is a named body of data, usually text. Entities are often used to represent single characters that cannot easily be entered on the keyboard; they are also used to represent pieces of standard ("boilerplate") text that occur in many documents, especially if there is a need to allow such text to be changed in one place only.''' An SGML entity is an abbreviation for part of a document. ...


Special characters can be represented either using entity references, or by means of numeric character references. An example of a numeric character reference is "&#x20AC;", which refers to the Euro symbol by means of its Unicode codepoint in hexadecimal. An SGML entity is an abbreviation for part of a document. ... A numeric character reference (NCR) is a common markup construct used in SGML and other SGML-based markup languages such as HTML and XML. It consists of a short sequence of characters that, in turn, represent a single character from the Universal Character Set (UCS) of Unicode. ... The euro (&#8364;; ISO 4217 code EUR) is the currency of twelve European Union member states: Austria, Belgium, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal, and Spain. ... The Unicode Standard, Version 5. ... In mathematics and computer science, hexadecimal, base-16, or simply hex, is a numeral system with a radix, or base, of 16, usually written using the symbols 0–9 and A–F, or a–f. ...


An entity reference is a placeholder that represents that entity. It consists of the entity's name preceded by an ampersand ("&") and followed by a semicolon (";"). XML has five predeclared entities: For the World of Warcraft ex-NPC, see Captain Placeholder. ... An ampersand (&), also commonly called an and sign is a logogram representing the conjunction and. ... A semicolon (  ;  ) is a punctuation mark. ... In computer languages, the term pre-declared refers to built-in information, encodings or tools that are available to a programmer, often in the form of entities, variables, objects, functions or instructions. ...

&amp; & ampersand
&lt; < less than
&gt; > greater than
&apos; ' apostrophe
&quot; " quotation mark

Here is an example using a predeclared XML entity to represent the ampersand in the name "AT&T":

 <company_name>AT&amp;T</company_name> 

Additional entities (beyond the predefined ones) can be declared in the document's Document Type Definition (DTD). A basic example of doing so in a minimal internal DTD follows. Declared entities can describe single characters or pieces of text, and can reference each other. The Extensible Markup Language (XML) is a general-purpose markup language. ...

 <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE example [  <!ENTITY copy "&#xA9;"> <!ENTITY copyright-notice "Copyright &copy; 2006, XYZ Enterprises"> ]> <example> &copyright-notice; </example> 

When viewed in a suitable browser, the XML document above appears as:

 <example> Copyright © 2006, XYZ Enterprises </example> 

Numeric character references

Numeric character references look like entity references, but instead of a name, they contain the "#" character followed by a number. The number (in decimal or "x"-prefixed hexadecimal) represents a Unicode code point. Unlike entity references, they are neither predeclared nor do they need to be declared in the document's DTD. They have typically been used to represent characters that are not easily encodable, such as an Arabic character in a document produced on a European computer. The ampersand in the "AT&T" example could also be escaped like this (decimal 38 and hexadecimal 26 both represent the Unicode code point for the "&" character): Number sign is one name for the symbol #, and is the preferred Unicode name for the codepoint represented by that glyph. ... In mathematics and computer science, hexadecimal, base-16, or simply hex, is a numeral system with a radix, or base, of 16, usually written using the symbols 0–9 and A–F, or a–f. ... Arabic redirects here. ... In computing and telecommunication, an escape character is one which has a special meaning in a sequence of characters. ...

 <company_name>AT&#38;T</company_name> <company_name>AT&#x26;T</company_name> 

See also numeric character references. A numeric character reference (NCR) is a common markup construct used in SGML and other SGML-based markup languages such as HTML and XML. It consists of a short sequence of characters that, in turn, represent a single character from the Universal Character Set (UCS) of Unicode. ...


Well-formed documents

A well-formed document must conform to the following rules, among others:

  • Non-empty elements are delimited by both a start-tag and an end-tag.
  • Empty elements may be marked with an empty-element (self-closing) tag, such as <IAmEmpty />. This is equal to <IAmEmpty></IAmEmpty>.
  • All attribute values are quoted with either single (') or double (") quotes. Single quotes close a single quote and double quotes close a double quote.
  • Tags may be nested but must not overlap. Each non-root element must be completely contained in another element.
  • The document complies with its declared character encoding. The encoding may be declared or implied externally, such as in "Content-Type" headers when a document is transported via HTTP, or internally, using explicit markup at the very beginning of the document. When no such declaration exists, a Unicode encoding is assumed, as defined by a Unicode Byte Order Mark before the document's first character. If the mark does not exist, UTF-8 encoding is assumed.

Element names are case-sensitive. For example, the following is a well-formed matching pair: Delimiters are marks which are used to seperate subfields of data. ... Hypertext Transfer Protocol (HTTP) is a communications protocol used to transfer or convey information on intranets and the World Wide Web. ... A byte-order mark (BOM) is the character at code point U+FEFF (zero-width no-break space), when that character is used to denote the endianness of a string of UCS/Unicode characters encoded in UTF-16 or UTF-32 and/or as a marker to indicate that text...

<Step> ... </Step>

whereas this is not

<Step> ... </step>

The careful choice of names for XML elements will convey the meaning of the data in the markup. This increases human readability while retaining the rigor needed for software parsing. A specialized markup language using SGML is used to write the electronic version of the Oxford English Dictionary. ...


Choosing meaningful names implies the semantics of elements and attributes to a human reader without reference to external documentation. However, this can lead to verbosity, which complicates authoring and increases file size. The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... DVD authoring, the process of creating a DVD from multimedia source materials. ... This page is a candidate to be copied to Wiktionary. ...


Automatic verification

It is relatively simple to verify that a document is well-formed or validated XML, because the rules of well-formedness and validation of XML are designed for portability of tools. The idea is that any tool designed to work with XML files will be able to work with XML files written in any XML language (or XML application). One example of using an independent tool follows:

  • load it into an XML-capable browser, such as Firefox or Internet Explorer 5.0
  • use a tool like xmlwf (usually bundled with expat)
  • parse the document, for instance in Ruby:
 irb> require "rexml/document" irb> include REXML irb> doc = Document.new(File.new("test.xml")).root 

Firefox redirects here. ... Windows Internet Explorer (formerly Microsoft Internet Explorer abbreviated MSIE), commonly abbreviated to IE, is a series of proprietary graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems starting in 1995. ... Expat is a stream-oriented XML 1. ...

Valid documents: XML semantics

By leaving the names, allowable hierarchy, and meanings of the elements and attributes open and definable by a customizable schema or DTD, XML provides a syntactic foundation for the creation of purpose specific, XML-based markup languages. The general syntax of such languages is rigid — documents must adhere to the general rules of XML, ensuring that all XML-aware software can at least read and understand the relative arrangement of information within them. The schema merely supplements the syntax rules with a set of constraints. Schemas typically restrict element and attribute names and their allowable containment hierarchies, such as only allowing an element named 'birthday' to contain 1 element named 'month' and 1 element named 'day', each of which has to contain only character data. The constraints in a schema may also include data type assignments that affect how information is processed; for example, the 'month' element's character data may be defined as being a month according to a particular schema language's conventions, perhaps meaning that it must not only be formatted a certain way, but also must not be processed as if it were some other type of data. 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 syntax constraints imposed by XML itself. ... Document Type Definition (DTD), defined slightly differently within the XML and SGML (the language XML was derived from) specifications, is one of several SGML and XML schema languages, and is also the term used to describe a document or portion thereof that is authored in the DTD language. ... In programming languages a data type defines a set of values and the allowable operations on those values[1]. For example, in the Java programming language, the int type represents the set of 32-bit integers ranging in value from -2,147,483,648 to 2,147,483,647, and...


An XML document that complies with a particular schema/DTD, in addition to being well-formed, is said to be valid.


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 constraints imposed by XML itself. A number of standard and proprietary XML schema languages have emerged for the purpose of formally expressing such schemas, and some of these languages are XML-based, themselves. A constraint is a limitation of possibilities. ...


Before the advent of generalised data description languages such as SGML and XML, software designers had to define special file formats or small languages to share data between programs. This required writing detailed specifications and special-purpose parsers and writers. A file format is a particular way to encode information for storage in a computer file. ... In engineering and manufacturing, the term specification has the following meanings: Technical requirement An essential technical requirement for items, materials, or services, including the procedures to be used to determine whether the requirement has been met. ... A writer is anyone who creates a written work, although the word more usually designates those who write creatively or professionally, or those who have written in many different forms. ...


XML's regular structure and strict parsing rules allow software designers to leave parsing to standard tools, and since XML provides a general, data model-oriented framework for the development of application-specific languages, software designers need only concentrate on the development of rules for their data, at relatively high levels of abstraction. A data model is a model that describes how data are represented and used in an abstract way. ...


Well-tested tools exist to validate an XML document "against" a schema: the tool automatically verifies whether the document conforms to constraints expressed in the schema. Some of these validation tools are included in XML parsers, and some are packaged separately. This page meets Wikipedias criteria for speedy deletion. ... One of Wikipedias rules to consider. ...


Other usages of schemas exist: XML editors, for instance, can use schemas to support the editing process (by suggesting valid elements and attributes names, etc).


DTD

The oldest schema format for XML is the Document Type Definition (DTD), inherited from SGML. While DTD support is ubiquitous due to its inclusion in the XML 1.0 standard, it is seen as limited for the following reasons: Document Type Definition (DTD), defined slightly differently within the XML and SGML (the language XML was derived from) specifications, is one of several SGML and XML schema languages, and is also the term used to describe a document or portion thereof that is authored in the DTD language. ... Document Type Definition (DTD), defined slightly differently within the XML and SGML (the language XML was derived from) specifications, is one of several SGML and XML schema languages, and is also the term used to describe a document or portion thereof that is authored in the DTD language. ...

  • It has no support for newer features of XML, most importantly namespaces.
  • It lacks expressiveness. Certain formal aspects of an XML document cannot be captured in a DTD.
  • It uses a custom non-XML syntax, inherited from SGML, to describe the schema.

DTD is still used in many applications because it is considered the easiest to read and write. Look up feature in Wiktionary, the free dictionary. ... An XML namespace is a W3C standard for providing uniquely named elements and attributes in an XML instance. ... The Standard Generalized Markup Language (SGML) is a metalanguage in which one can define markup languages for documents. ...


XML Schema

Main article: XML Schema (W3C)

A newer XML schema language, described by the W3C as the successor of DTDs, is XML Schema, or more informally referred to by the initialism for XML Schema instances, XSD (XML Schema Definition). XSDs are far more powerful than DTDs in describing XML languages. They use a rich datatyping system, allow for more detailed constraints on an XML document's logical structure, and must be processed in a more robust validation framework. XSDs also use an XML-based format which makes it possible to use ordinary XML tools to help process them, although XSD implementations require much more than just the ability to read XML. This article is about the W3Cs XML Schema language. ... 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 syntax constraints imposed by XML itself. ... This article is about the W3Cs XML Schema language. ... Look up acronym, initialism, alphabetism in Wiktionary, the free dictionary. ... In computer science, a datatype or data type (often simply a type) is a name or label for a set of values and some operations which one can perform on that set of values. ... Robust means healthy, strong, durable, and often adaptable, innovative, flexible. ...


Criticisms of XSD include the following:

  • The specification is very large, which makes it difficult to understand and implement.
  • The XML-based syntax leads to verbosity in schema description, which makes XSDs harder to read and write.
  • Schema validation can be an expensive addition to XML parsing, especially for high volume systems.
  • The modeling capabilities are very limited, with no ability to allow attributes to influence content models.
  • The type derivation model is very limited, in particular that derivation by extension is rarely useful.
  • Database-related data transfer has been supported with arcane ideas such as nillability but the requirements of industrial publishing are under-supported.
  • The key/keyref/uniqueness mechanisms are not type aware
  • The PSVI concept (Post Schema Validation Infoset) does not have a standard XML representation or Application Programming Interface, thus it works against vendor independence unless revalidation is performed.

The movement of data from one location to another is called data transfer. ... In predicate logic and technical fields that depend on it, uniqueness quantification, or unique existential quantification, is an attempt to formalise the notion of something being true for exactly one thing, or exactly one thing of a certain type. ... This article needs cleanup. ... API and Api redirect here. ...

RELAX NG

Main article: RELAX NG

Another popular schema language for XML is RELAX NG. Initially specified by OASIS, RELAX NG is now also an ISO international standard (as part of DSDL). It has two formats: an XML based syntax and a non-XML compact syntax. The compact syntax aims to increase readability and writability but, since there is a well-defined way to translate the compact syntax to the XML syntax and back again by means of James Clark's Trang conversion tool, the advantage of using standard XML tools is not lost. RELAX NG has a simpler definition and validation framework than XML Schema, making it easier to use and implement. It also has the ability to use datatype framework plug-ins; a RELAX NG schema author, for example, can require values in an XML document to conform to definitions in XML Schema Datatypes. In computing, RELAX NG (REgular LAnguage for XML Next Generation) is a schema language for XML, based on Murata Makotos RELAX and James Clarks TREX. A RELAX NG schema specifies a pattern for the structure and content of an XML document. ... In computing, RELAX NG (REgular LAnguage for XML Next Generation) is a schema language for XML, based on Murata Makotos RELAX and James Clarks TREX. A RELAX NG schema specifies a pattern for the structure and content of an XML document. ... The Organization for the Advancement of Structured Information Standards (OASIS) is a global consortium that drives the development, convergence and adoption of e-business and web service standards. ... Document Schema Definition Languages (DSDL) is a framework within which multiple validation tasks of different types can be applied to an XML document in order to achieve more complete validation results than just the application of a single technology. ... Clark, (February 23, 1964) is the author of groff and expat and has done much work with open-source software and XML. Born in London, Charterhouse School|Charterhouse]] and Merton College, Oxford, Clark has lived in Bangkok, Thailand since 1995, and is now a permanent resident. ... In computer science, a datatype or data type (often simply a type) is a name or label for a set of values and some operations which one can perform on that set of values. ... A plugin (or plug-in) is a computer program that can, or must, interact with another program to provide a certain, usually very specific, function. ...


ISO DSDL and Other Schema Languages

The ISO DSDL (Document Schema Description Languages) standard brings together a comprehensive set of small schema languages, each targeted at specific problems. DSDL includes RELAX NG full and compact syntax, Schematron assertion language, and languages for defining datatypes, character repertoire constraints, renaming and entity expansion, and namespace-based routing of document fragments to different validators. DSDL schema languages do not have the vendor support of XML Schemas yet, and are to some extent a grassroots reaction of industrial publishers to the lack of utility of XML Schemas for publishing. Document Schema Definition Languages (DSDL) is a framework within which multiple validation tasks of different types can be applied to an XML document in order to achieve more complete validation results than just the application of a single technology. ... In computing, RELAX NG (REgular LAnguage for XML Next Generation) is a schema language for XML, based on Murata Makotos RELAX and James Clarks TREX. A RELAX NG schema specifies a pattern for the structure and content of an XML document. ... The Schematron is an XML structure validation language for making assertion about the presence or absence of patterns in trees. ... This article is about routing (or routeing) in computer networks. ... “Publisher” redirects here. ...


Some schema languages not only describe the structure of a particular XML format but also offer limited facilities to influence processing of individual XML files that conform to this format. DTDs and XSDs both have this ability; they can for instance provide attribute defaults. RELAX NG and Schematron intentionally do not provide these; for example the infoset augmentation facility. XML Information Set (Infoset) is a W3C specification describing an abstract data model of an XML document in terms of a set of information items. ...


International use

XML supports the direct use of almost any Unicode character (other than the ones that have special symbolic meaning in XML, itself, such as the open corner bracket, "<") in element names, attributes, comments, character data, and processing instructions. Therefore, the following is a well-formed XML document, even though it includes both Chinese and Cyrillic characters: The Cyrillic alphabet (pronounced also called azbuka, from the old name of the first two letters) is actually a family of alphabets, subsets of which are used by certain Slavic languages — Belarusian, Bulgarian, Macedonian, Russian, Rusyn, Serbian, and Ukrainian—as well as many other languages of the former Soviet Union...

 <?xml version="1.0" encoding="UTF-8"?> <俄語>Данные</俄語> 

Displaying XML on the web

XML documents do not carry information about how to display the data. Without using CSS or XSL, a generic XML document is rendered as raw XML text by most web browsers. Some display it with 'handles' (e.g. + and - signs in the margin) that allow parts of the structure to be expanded or collapsed with mouse-clicks. In web development, Cascading Style Sheets (CSS) is a stylesheet language used to describe the presentation of a document written in a markup language. ... The eXtensible Stylesheet Language (XSL) is a family of transformation languages which allows one to describe how files encoded in the XML standard are to be formatted or transformed. ... An example of a Web browser (Mozilla Firefox) A web browser is a software application that enables a user to display and interact with text, images, videos, music and other information typically located on a Web page at a website on the World Wide Web or a local area network. ...


In order to style the rendering in a browser with CSS, the XML document must include a reference to the stylesheet: CSS Zen garden with the Paravion style sheet CSS Zen garden with the Uncultivated style sheet Cascading Style Sheets (CSS) is a computer language used to describe the presentation of a structured document written in HTML, XHTML or XML. The CSS specification is maintained by the World Wide Web Consortium...

 <?xml-stylesheet type="text/css" href="myStyleSheet.css"?> 

Note that this is different from specifying such a stylesheet in HTML, which uses the <link> element.


Extensible Stylesheet Language (XSL) can be used to alter the format of XML data, either into HTML or other formats that are suitable for a browser to display. The eXtensible Stylesheet Language (XSL) is a family of transformation languages which allows one to describe how files encoded in the XML standard are to be formatted or transformed. ...


To specify client-side XSL Transformation (XSLT), the following processing instruction is required in the XML: Client/Server is a network application architecture which separates the client (usually the graphical user interface) from the server. ... Diagram of the basic elements and process flow of Extensible Stylesheet Language Transformations. ...

 <?xml-stylesheet type="text/xsl" href="myTransform.xslt"?> 

Client-side XSLT is supported by many web browsers, but not Opera before version 9.0. An alternative, rather than being dependent on the end-user's browser capabilities, is to use XSL to convert XML into a displayable format on the server. The end-user is not aware of what has gone on 'behind the scenes'; all they see is well-formatted, displayable data. An example of a Web browser (Mozilla Firefox) A web browser is a software application that enables a user to display and interact with text, images, videos, music and other information typically located on a Web page at a website on the World Wide Web or a local area network. ... Opera is an Internet suite which handles common internet-related tasks, including visiting web sites, sending and receiving e-mail messages, managing contacts, and online chat. ... Economics and commerce define an end-user as the person who uses a product. ... In information technology, a server is an application or device that performs services for connected clients as part of a client-server architecture. ...


See the XSLT article for an example of server-side XSLT in action. Diagram of the basic elements and process flow of Extensible Stylesheet Language Transformations. ...


XML extensions

  • XPath makes it possible to refer to individual parts of an XML document. This provides random access to XML data for other technologies, including XSLT, XSL-FO, XQuery etc. XPath expressions can refer to all or part of the text, data and values in XML elements, attributes, processing instructions, comments etc. They can also access the names of elements and attributes. XPaths can be used in both valid and well-formed XML, with and without defined namespaces.
  • XInclude defines the ability for XML files to include all or part of an external file. When processing is complete, the final XML infoset has no XInclude elements, but instead has copied the documents or parts thereof into the final infoset. It uses XPath to refer to a portion of the document for partial inclusions.
  • XQuery is to XML what SQL and PL/SQL are to relational databases: ways to access, manipulate and return XML.
  • XML Namespaces enable the same document to contain XML elements and attributes taken from different vocabularies, without any naming collisions occurring.
  • XML Signature defines the syntax and processing rules for creating digital signatures on XML content.
  • XML Encryption defines the syntax and processing rules for encrypting XML content.
  • XPointer is a system for addressing components of XML-based internet media.

XML files may be served with a variety of Media types. RFC 3023 defines the types "application/xml" and "text/xml", which say only that the data is in XML, and nothing about its semantics. The use of "text/xml" has been criticized as a potential source of encoding problems but is now in the process of being deprecated.[5] RFC 3023 also recommends that XML-based languages be given media types beginning in "application/" and ending in "+xml"; for example "application/atom+xml" for Atom. This page discusses further XML and MIME. XPath (XML Path Language) is an expression language for addressing portions of an XML document, or for computing values (strings, numbers, or boolean values) based on the content of an XML document. ... XInclude is a processing model and syntax for general purpose inclusion. ... XQuery is a query language (with some programming language features) that is designed to query collections of XML data. ... SQL (IPA: or ), commonly expanded as Structured Query Language, is a computer language designed for the retrieval and management of data in relational database management systems, database schema creation and modification, and database object access control management. ... PL/SQL (Procedural Language/Structured Query Language) is Oracle Corporations proprietary server-based procedural extension to the SQL database language. ... A relational database is a database based on the relational model. ... An XML namespace is a W3C standard for providing uniquely named elements and attributes in an XML instance. ... A naming collision, an undesirable occurance in computer science, describes a situation in which multiple elements share names in a system demanding unique naming. ... XML Signature (also called XMLDsig) is a W3C recommendation that defines an XML syntax for digital signatures. ... In cryptography, digital signatures are a method of authenticating digital information often treated, sometimes too closely, as analogous to a physical signature on paper. ... XML Encryption is a specification that defines how to encrypt the content of an XML element. ... Encrypt redirects here. ... XPointer is a system for addressing components of XML based internet media. ... For mime as an art form, see mime artist. ... The name Atom applies to a pair of related standards. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...


Processing XML files

Three traditional techniques for processing XML files are:

  • Using a programming language and the SAX API.
  • Using a programming language and the DOM API.
  • Using a transformation engine and a filter

More recent and emerging techniques for processing XML files are: The Simple API for XML (SAX) is a serial access parser API for XML. SAX provides a mechanism for reading data from an XML document. ... API and Api redirect here. ... Document Object Model (DOM) is a form of representation of structured documents as an object-oriented model. ... API and Api redirect here. ...

  • Push Parsing
  • Data binding
  • Non-extractive XML Processing API such as VTD-XML

Virtual Token Descriptor for eXtensible Markup Language (VTD-XML) refers to a collection of efficient XML processing technologies centered around a non-extractive XML parsing technique called Virtual Token Descriptor (VTD). ...

Simple API for XML (SAX)

SAX is a lexical, event-driven interface in which a document is read serially and its contents are reported as "callbacks" to various methods on a handler object of the user's design. SAX is fast and efficient to implement, but difficult to use for extracting information at random from the XML, since it tends to burden the application author with keeping track of what part of the document is being processed. It is better suited to situations in which certain types of information are always handled the same way, no matter where they occur in the document. The Simple API for XML (SAX) is a serial access parser API for XML. SAX provides a mechanism for reading data from an XML document. ... In computer science, lexical analysis is the process of converting a sequence of characters into a sequence of tokens. ... Event-driven programming is a computer programming paradigm. ... Callback can mean: Callback (computer science), executable code that is passed as a parameter to other code Callback (telecommunications), the telecommunications event that occurs when the originator of a call is immediately called back in a second call as a response Callback (comedy), a joke which refers to one previously... In object-oriented programming, the term method refers to a subroutine that is exclusively associated either with a class (called class methods, static methods, or factory methods) or with an object (called instance methods). ... An event handler is a part of a computer program created to tell the program how to act in response to a specific event (e. ...


DOM

DOM is an interface-oriented Application Programming Interface that allows for navigation of the entire document as if it were a tree of "Node" objects representing the document's contents. A DOM document can be created by a parser, or can be generated manually by users (with limitations). Data types in DOM Nodes are abstract; implementations provide their own programming language-specific bindings. DOM implementations tend to be memory intensive, as they generally require the entire document to be loaded into memory and constructed as a tree of objects before access is allowed. Hierarchy of objects in an example HTML DOM - Document Object Model The Document Object Model (DOM) is a platform- and language-independent standard object model for representing HTML or XML and related formats. ... Look up interface in Wiktionary, the free dictionary. ... API and Api redirect here. ... A node is a basic unit used to build data structures, such as linked lists and tree data structures. ... In strictly mathematical branches of computer science the term object is used in a purely mathematical sense to refer to any thing. While this interpretation is useful in the discussion of abstract theory, it is not concrete enough to serve as a primitive datatype in the discussion of more concrete... Computer programming (often simply programming) is the craft of implementing one or more interrelated abstract algorithms using a particular programming language to produce a concrete computer program. ... Binding can mean: Binding (computer science) - a tie (for example) to certain names in programming languages Binding (knot) - A type of knot Binding (linguistics) - a property relating to anaphors (pronouns and R-expressions) and c-command Bookbinding - the protective cover of a book; and the art of constructing this Ski... For other uses, see Memory (disambiguation). ...


Transformation engines and filters

A filter in the Extensible Stylesheet Language (XSL) family can transform an XML file for displaying or printing. A filter is a computer program to process a data stream. ... The eXtensible Stylesheet Language (XSL) is a family of transformation languages which allows one to describe how files encoded in the XML standard are to be formatted or transformed. ... Only meanings of encyclopedic scope are listed here for disambiguation purposes. ... A computer printer, or more commonly a printer, produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper transparencies. ...

  • XSL-FO is a declarative, XML-based page layout language. An XSL-FO processor can be used to convert an XSL-FO document into another non-XML format, such as PDF.
  • XSLT is a declarative, XML-based document transformation language. An XSLT processor can use an XSLT stylesheet as a guide for the conversion of the data tree represented by one XML document into another tree that can then be serialized as XML, HTML, plain text, or any other format supported by the processor.
  • XQuery is a W3C language for querying, constructing and transforming XML data.
  • XPath is a DOM-like node tree data model and path expression language for selecting data within XML documents. XSL-FO, XSLT and XQuery all make use of XPath. XPath also includes a useful function library.

XSL Formatting Objects, or XSL-FO, is an XML markup language for document formatting. ... Desktop publishing, or DTP, is the process of editing and layout of printed material intended for publication, such as books, magazines, brochures, and the like using a personal computer. ... Processor can mean: A central processing unit of a computer. ... PDF is an abbreviation with several meanings: Portable Document Format Post-doctoral fellowship Probability density function There also is an electronic design automation company named PDF Solutions. ... ... To convert into streamable form. ... XQuery is a query language (with some programming language features) that is designed to query collections of XML data. ... In general, a query is a form of questioning, in a line of inquiry. ... XPath (XML Path Language) is an expression language for addressing portions of an XML document, or for computing values (strings, numbers, or boolean values) based on the content of an XML document. ... A data model is a model that describes how data are represented and used in an abstract way. ... In query languages, path expressions identify an object by describing how to navigate to it in some (possibly implicit) Graph of objects. ... Illustration of an application which may use libvorbisfile. ...

Push Parsing

A form of XML access that has become increasingly popular in recent years is push parsing,[6][7] which treats the document as if it were a series of items which are being read in sequence. This allows for writing of recursive-descent parsers in which the structure of the code performing the parsing mirrors the structure of the XML being parsed, and intermediate parsed results can be used and accessed as local variables within the methods performing the parsing, or passed down (as method parameters) into lower-level methods, or returned (as method return values) to higher-level methods. For instance, in the Java programming language, the StAX framework can be used to create what is essentially an 'iterator' which sequentially visits the various elements, attributes, and data in an XML document. Code which uses this 'iterator' can test the current item (to tell, for example, whether it is a start or end element, or text), and inspect its attributes (local name, namespace, values of XML attributes, value of text, etc.), and can also request that the iterator be moved to the 'next' item. The code can thus extract information from the document as it traverses it. One significant advantage of push-parsing methods is that they typically are much more speed- and memory-efficient than SAX and DOM styles of parsing XML. Another advantage is that the recursive-descent approach tends to lend itself easily to keeping data as typed local variables in the code doing the parsing, while SAX, for instance, typically requires a parser to manually maintain intermediate data within a stack of elements which are parent elements of the element being parsed. This tends to mean that push-parsing code is often much more straightforward to understand and maintain than SAX parsing code. Some potential disadvantages of push parsing are that it is a newer approach which is not as well known among XML programmers (although it is by far the most common method used for writing compilers and interpreters for languages other than XML), and that most existing push parsers cannot yet perform advanced processing such as XML schema validation as they parse a document. A recursive descent parser is a top-down parser built from a set of mutually-recursive procedures (or a non-recursive equivalent) where each such procedure usually implements one of the production rules of the grammar. ... “Java language” redirects here. ... Streaming API for XML (StAX) is an application programming interface (API) to read and write XML documents in the Java programming language. ...


Data binding

Another form of XML Processing API is data binding, where XML data is made available as a custom, strongly typed programming language data structure, in contrast to the interface-oriented DOM. Example data binding systems are the Java Architecture for XML Binding (JAXB)[8] and the Strathclyde Novel Architecture for Querying XML (SNAQue).[9] XML data binding refers to the process of representing the information in an XML document as an object in computer memory. ... “Java language” redirects here. ... This article is about building architecture. ... Java Architecture for XML Binding (JAXB) allows Java developers to edit and create XML using familiar Java objects. ...


Non-extractive XML Processing API

Non-extractive XML Processing API is a new and emerging category of parsers. The most representative is VTD-XML, which abolishes the object-oriented modeling of XML hierarchy and instead uses 64-bit Virtual Token Descriptors (encoding offsets, lengths, depths, and types) of XML tokens. VTD-XML's approach enables a number of interesting features/enhancements, such as high performance, low memory usage [10], ASIC implementation [11], incremental update [12], and native XML indexing [13]. Virtual Token Descriptor for eXtensible Markup Language (VTD-XML) refers to a collection of efficient XML processing technologies centered around a non-extractive XML parsing technique called Virtual Token Descriptor (VTD). ...


Specific XML applications and editors

The native file format of OpenOffice.org, AbiWord, and Apple's iWork applications is XML. Some parts of Microsoft Office 2007 are also able to edit XML files with a user-supplied schema (but not a DTD), and Microsoft has released a file format compatibility kit for Office 2003 that allows previous versions of Office to save in the new XML based format. There are dozens of other XML editors available. A native format, in the context of software applications, refers to the file format which the application works with during creation, edition or publication of a file. ... OpenOffice. ... AbiWord is a Free Software word processor licensed under the GNU General Public License. ... Apple Inc. ... iWork is a suite of applications created by Apple Inc. ... Microsoft Office is an office suite from Microsoft for Microsoft Windows and Apple Mac OS X operating systems. ... An XML editor is a markup language editor with added functionality to facilitate the editing of XML. This could be done in plain text in a text editor such as Vim, with all the code visible. ...


History

The versatility of SGML for dynamic information display was understood by early digital media publishers in the late 1980s prior to the rise of the Internet.[14][15] By the mid-1990s some practitioners of SGML had gained experience with the then-new World Wide Web, and believed that SGML offered solutions to some of the problems the Web was likely to face as it grew. Dan Connolly added SGML to the list of W3C's activities when he joined the staff in 1995; work began in mid-1996 when Jon Bosak developed a charter and recruited collaborators. Bosak was well connected in the small community of people who had experience both in SGML and the Web. He received support in his efforts from Microsoft. The Standard Generalized Markup Language (SGML) is a metalanguage in which one can define markup languages for documents. ... WWWs historical logo designed by Robert Cailliau The World Wide Web (commonly shortened to the Web) is a system of interlinked, hypertext documents accessed via the Internet. ... Dan Connolly received a B.S. in Computer Science from the University of Texas at Austin in 1990. ... Jon Bosak led the creation of the XML specification at the W3C. Tim Bray, who was one of the editors of the XML specification, has this to say in his note on Bosak in his annotated version of the spec: Jon Bosak is the single person without whose efforts XML... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ...


XML was compiled by a working group of eleven members,[16] supported by an (approximately) 150-member Interest Group. Technical debate took place on the Interest Group mailing list and issues were resolved by consensus or, when that failed, majority vote of the Working Group. The decision record was compiled by Michael Sperberg-McQueen on December 4th 1997.[17] James Clark served as Technical Lead of the Working Group, notably contributing the empty-element "<empty/>" syntax and the name "XML". Other names that had been put forward for consideration included "MAGMA" (Minimal Architecture for Generalized Markup Applications), "SLIM" (Structured Language for Internet Markup) and "MGML" (Minimal Generalized Markup Language). The co-editors of the specification were originally Tim Bray and Michael Sperberg-McQueen. Halfway through the project Bray accepted a consulting engagement with Netscape, provoking vociferous protests from Microsoft. Bray was temporarily asked to resign the editorship. This led to intense dispute in the Working Group, eventually solved by the appointment of Microsoft's Jean Paoli as a third co-editor. Wikipedia does not have an article with this exact name. ... Co-editor, Extensible Markup Language (XML) 1. ... Clark, (February 23, 1964) is the author of groff and expat and has done much work with open-source software and XML. Born in London, Charterhouse School|Charterhouse]] and Merton College, Oxford, Clark has lived in Bangkok, Thailand since 1995, and is now a permanent resident. ... Timothy William Bray (born 1955), commonly known as Tim Bray, co-invented XML and XML namespaces while an Invited Expert at the World Wide Web Consortium between 1996 and 1999. ... Co-editor, Extensible Markup Language (XML) 1. ... Netscape Communications Corporation was the publisher of the Netscape Navigator web browser as well as many other internet and intranet client and server software products. ...


The XML Working Group never met face-to-face; the design was accomplished using a combination of email and weekly teleconferences. The major design decisions were reached in twenty weeks of intense work between July and November of 1996, when the first Working Draft of an XML specification was published.[18] Further design work continued through 1997, and XML 1.0 became a W3C Recommendation on February 10, 1998. For the band, see 1997 (band). ... The World Wide Web Consortium (W3C) is a consortium that produces standards&#8212;recommendations, as they call them&#8212;for the World Wide Web. ... is the 41st day of the year in the Gregorian calendar. ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ...


XML 1.0 achieved the Working Group's goals of Internet usability, general-purpose usability, SGML compatibility, facilitation of easy development of processing software, minimization of optional features, legibility, formality, conciseness, and ease of authoring. Like its antecedent SGML, XML allows for some redundant syntactic constructs and includes repetition of element identifiers. In these respects, terseness was not considered essential in its structure.


Sources

XML is a profile of an ISO standard SGML, and most of XML comes from SGML unchanged. From SGML comes the separation of logical and physical structures (elements and entities), the availability of grammar-based validation (DTDs), the separation of data and metadata (elements and attributes), mixed content, the separation of processing from representation (processing instructions), and the default angle-bracket syntax. Removed were the SGML Declaration (XML has a fixed delimiter set and adopts Unicode as the document character set). The Standard Generalized Markup Language (SGML) is a metalanguage in which one can define markup languages for documents. ... The Unicode Standard, Version 5. ... A character encoding or character set (sometimes referred to as code page) consists of a code that pairs a sequence of characters from a given set with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the storage of text in computers...


Other sources of technology for XML were the Text Encoding Initiative (TEI), which used a simpler syntax than full SGML; HTML, in which elements were synchronous with their resource, the separation of document character set from resource encoding, the xml:lang attribute, and the HTTP notion that metadata accompanied the resource rather than being needed at the declaration of a link; and the Extended Reference Concrete Syntax (ERCS), from which XML 1.0's naming rules were taken, and which had introduced hexadecimal numeric character references and the concept of references to make available all Unicode characters. The Text Encoding Initiative (TEI) is a consortium of institutions and research projects which collectively maintains and develops a standard for the representation of texts in digital form. ... HTML, an initialism of Hypertext Markup Language, is the predominant markup language for web pages. ... HTTP (for HyperText Transfer Protocol) is the primary method used to convey information on the World Wide Web. ...


Ideas that developed during discussion which were novel in XML, were the algorithm for encoding detection and the encoding header, the processing instruction target, the xml:space attribute, and the new close delimiter for empty element tags.


Versions

There are two current versions of XML. The first, XML 1.0, was initially defined in 1998. It has undergone minor revisions since then, without being given a new version number, and is currently in its fourth edition, as published on August 16, 2006. It is widely implemented and still recommended for general use. The second, XML 1.1, was initially published on February 4, 2004, the same day as XML 1.0 Third Edition, and is currently in its second edition, as published on August 16, 2006. It contains features — some contentious — that are intended to make XML easier to use in certain cases[19] - mainly enabling the use of line-ending characters used on EBCDIC platforms, and the use of scripts and characters absent from Unicode 2.0. XML 1.1 is not very widely implemented and is recommended for use only by those who need its unique features. [20] Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ... is the 228th day of the year (229th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 35th day of the year in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... is the 228th day of the year (229th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... EBCDIC (Extended Binary Coded Decimal Interchange Code) is an 8-bit character encoding (code page) used on IBM mainframe operating systems, like z/OS, OS/390, VM and VSE, as well as IBM minicomputer operating systems like OS/400 and i5/OS. It is also employed on various non-IBM...


XML 1.0 and XML 1.1 differ in the requirements of characters used for element and attribute names: XML 1.0 only allows characters which are defined in Unicode 2.0, which includes most world scripts, but excludes those which were added in later Unicode versions. Among the excluded scripts are Mongolian, Cambodian, Amharic, Burmese, and others. Not to be confused with the Aramaic language. ...


Almost any Unicode character can be used in the character data and attribute values of an XML 1.1 document, even if the character is not defined, aside from having a code point, in the current version of Unicode. The approach in XML 1.1 is that only certain characters are forbidden, and everything else is allowed, whereas in XML 1.0, only certain characters are explicitly allowed, thus XML 1.0 cannot accommodate the addition of characters in future versions of Unicode.


In character data and attribute values, XML 1.1 allows the use of more control characters than XML 1.0, but, for "robustness", most of the control characters introduced in XML 1.1 must be expressed as numeric character references. Among the supported control characters in XML 1.1 are two line break codes that must be treated as whitespace. Whitespace characters are the only control codes that can be written directly. In computing, a control character or non-printing character, is a code point (a number) in a character set that does not in itself represent a written symbol. ...


There are also discussions on an XML 2.0, although it remains to be seen [vague] if such will ever come about. XML-SW (SW for skunk works), written by one of the original developers of XML, contains some proposals for what an XML 2.0 might look like: elimination of DTDs from syntax, integration of namespaces, XML Base and XML Information Set (infoset) into the base standard. A modern Skunk Works project leverages an older: LASRE atop the SR-71 Blackbird. ... A namespace is a context in which a group of one or more identifiers might exist. ... This page is a candidate for speedy deletion. ... XML Information Set (Infoset) is a W3C recommendation. ...


The World Wide Web Consortium also has an XML Binary Characterization Working Group doing preliminary research into use cases and properties for a binary encoding of the XML infoset. The working group is not chartered to produce any official standards. Since XML is by definition text-based, ITU-T and ISO are using the name Fast Infoset for their own binary infoset to avoid confusion (see ITU-T Rec. X.891 | ISO/IEC 24824-1).


Patent claims

In October 2005 the small company Scientigo publicly asserted that two of its patents, U.S. Patent 5,842,213  and U.S. Patent 6,393,426 , apply to the use of XML. The patents cover the "modeling, storage and transfer [of data] in a particular non-hierarchical, non-integrated neutral form", according to their applications, which were filed in 1997 and 1999. Scientigo CEO Doyal Bryant expressed a desire to "monetize" the patents but stated that the company was "not interested in having us against the world." He said that Scientigo was discussing the patents with several large corporations.[21] Scientigo is a United States company based in Charlotte, North Carolina that began asserting patent claims over XML technology in 2005. ...


XML users and independent experts responded to Scientigo's claims with widespread skepticism and criticism. Some derided the company as a patent troll. Tim Bray described any claims that the patents covered XML as "ridiculous on the face of it".[22] Patent troll is a pejorative term used for a person or company that enforces its patents against one or more alleged infringers in a matter considered unduly aggressive or opportunistic (see List of patent trolls for examples). ... Timothy William Bray (born 1955), commonly known as Tim Bray, co-invented XML and XML namespaces while an Invited Expert at the World Wide Web Consortium between 1996 and 1999. ...


Because there exists a large amount of prior art relating to XML, including SGML, some legal experts believed it would be difficult for Scientigo to enforce its patents through litigation.[citation needed] This article or section cites very few or no references or sources. ... The Standard Generalized Markup Language (SGML) is a metalanguage in which one can define markup languages for documents. ...


Critique of XML

Commentators have offered various critiques of XML, suggesting circumstances where XML provides both advantages and potential disadvantages.[23]

 "XML is really just data dressed up as a hooker."
-Dave Thomas[24]

Dave Thomas is a computer programmer and author/editor. ...

Advantages of XML

  • XML is heavily used as a format for document storage and processing, both online and offline.
  • It is based on international standards.
  • It can be updated incrementally.
  • It allows validation using schema languages such as XSD and Schematron, which makes effective unit-testing, firewalls, acceptance testing, contractual specification and software construction easier.
  • The hierarchical structure is suitable for most (but not all) types of documents.
  • It manifests as plain text files, which are less restrictive than other proprietary document formats.
  • It is platform-independent, thus relatively immune to changes in technology.
  • Forward and backward compatibility are relatively easy to maintain despite changes in DTD or Schema.
  • Its predecessor, SGML, has been in use since 1986, so there is extensive experience and software available.
  • An element fragment of a well-formed XML document is also a well-formed XML document.

The Unicode Standard, Version 5. ... Computer science, or computing science, is the study of the theoretical foundations of information and computation and their implementation and application in computer systems. ... A binary tree, a simple type of branching linked data structure. ... This article is about the data structure. ... Look up list in Wiktionary, the free dictionary. ... In computer science, a tree is a widely-used computer data structure that emulates a tree structure with a set of linked nodes. ... In computer science, self-documenting refers to the ability of a piece of code or something else to require users have little or no previous knowledge of its specification, purpose and behavior to use it effectively. ... This article does not cite any references or sources. ... This is a disambiguation page &#8212; a navigational aid which lists other pages that might otherwise share the same title. ... For other uses, see Syntax (disambiguation). ... An example of parsing a mathematical expression. ... A parser is a computer program or a component of a program that analyses the grammatical structure of an input, with respect to a given formal grammar, a process known as parsing. ... Standards are produced by many organisations, some for internal usage only, others for use by a groups of people, groups of companies, or a subsection of an industry. ... An XML Schema Definition (XSD) is an instance of a W3C XML Schema. ... The Schematron is an XML structure validation language for making assertion about the presence or absence of patterns in trees. ... A hierarchy (in Greek: , derived from — hieros, sacred, and — arkho, rule) is a system of ranking and organizing things or people, where each element of the system (except for the top element) is a subordinate to a single other element. ... Computer files can be divided into two broad categories: binary and text. ... Year 1986 (MCMLXXXVI) was a common year starting on Wednesday (link displays 1986 Gregorian calendar). ...

Disadvantages of XML

  • XML syntax is redundant or large relative to binary representations of similar data.[25]
  • The redundancy may affect application efficiency through higher storage, transmission and processing costs.[26][27]
  • XML syntax is verbose relative to other alternative 'text-based' data transmission formats.[28][29]
  • No intrinsic data type support: XML provides no specific notion of "integer", "string", "boolean", "date", and so on.[30][31]
  • The hierarchical model for representation is limited in comparison to the relational model or an object oriented graph.[32][33]
  • Expressing overlapping (non-hierarchical) node relationships requires extra effort.[34]
  • XML namespaces are problematic to use and namespace support can be difficult to correctly implement in an XML parser.[35]
  • XML is commonly depicted as "self-documenting" but this depiction ignores critical ambiguities.[36][37]

In programming languages a data type defines a set of values and the allowable operations on those values[1]. For example, in the Java programming language, the int type represents the set of 32-bit integers ranging in value from -2,147,483,648 to 2,147,483,647, and... In a hierarchical data model, data are organized into a tree-like structure. ... The relational model for database management is a database model based on predicate logic and set theory. ... In computer science, object-oriented programming, OOP for short, is a computer programming paradigm. ... In computer science, self-documenting refers to the ability of a piece of code or something else to require users have little or no previous knowledge of its specification, purpose and behavior to use it effectively. ...

See also

AJAX redirects here. ... In telecommunications and computer networking abstract syntax notation one (ASN.1) is a standard, flexible method that describes data structures for representing, encoding, transmitting, and decoding data. ... This article may be too technical for most readers to understand. ... The term CDATA (), meaning character data, is used for distinct, but related purposes in the markup languages SGML and XML. The term indicates that a certain portion of the document is general character data, rather than non-character data or character data with a more specific, limited structure. ... The following tables compare XML compatibility and support for a number of layout engines. ... DITA (Darwin Information Typing Architecture) is an XML-based architecture for authoring, producing, and delivering technical information. ... DocBook is a markup language for technical documentation, originally intended for authoring technical documents related to computer hardware and software but which can be used for any other sort of documentation. ... Electronic Business using eXtensible Markup Language, commonly known as e-business XML, or ebXML (pronounced ee-bee-ex-em-el) as it is typically referred to as, is a family of XML based standards sponsored by OASIS and UN/CEFACT whose mission is to provide an open, XML-based infrastructure... Binary XML, or Binary Extensible Markup Language, refers to any specification which attempts to encode an XML document in a binary data format, rather than plain text. ... Extensible Binary Meta Language, or EBML, is a generalized file format for (theoretically) any kind of data, aiming to be a binary equivalent to XML. It was originally developed for the Matroska audio/video container format. ... The Extensible Metadata Platform or XMP is a specific type of extensible markup language used in PDF, photography and photo editing applications. ... This is a new experience and I love it. ... This page aims to list articles related XML markup languages. ... An S-expression (S stands for symbolic) is a convention for representing data or an expression in a computer program in a text form. ... Security Assertion Markup Language (SAML) is an XML standard for exchanging authentication and authorization data between security domains, that is, between an identity provider (a producer of assertions) and a service provider (a consumer of assertions). ... In computer science, in the context of data storage and transmission, serialization is the process of saving an object onto a storage medium (such as a file, or a memory buffer) or to transmit it across a network connection link, either in binary form, or in some human-readable text... Single source publishing or single sourcing allows the same content to be used in different documents and in various formats. ... This article or section does not cite its references or sources. ... A collection of decorative soaps used for human hygiene purposes. ... From the OASIS Site: UBL, the Universal Business Language, is the product of an international effort to define a royalty-free library of standard electronic XML business documents such as purchase orders and invoices. ... XBRL (eXtensible Business Reporting Language) is an emerging XML-based standard to define and exchange business and financial performance information. ... WAP Binary XML (WBXML) is a binary representation of XML. Its goal is to allow XML documents to be transmitted in a compact manner over mobile networks. ... XML data binding refers to the process of representing the information in an XML document as an object in computer memory. ... XML/EDIFACT combines EDIFACT content with XML syntax. ... An XML editor is a markup language editor with added functionality to facilitate the editing of XML. This could be done in plain text in a text editor such as Vim, with all the code visible. ... XML Information Set (Infoset) is a W3C recommendation. ... API and Api redirect here. ... Hierarchy of objects in an example HTML DOM - Document Object Model The Document Object Model (DOM) is a platform- and language-independent standard object model for representing HTML or XML and related formats. ... The Simple API for XML (SAX) is a serial access parser API for XML. SAX provides a mechanism for reading data from an XML document. ... Streaming API for XML (StAX) is an application programming interface (API) to read and write XML documents in the Java programming language. ... ECMAScript for XML (E4X) is a programming language extension that adds native XML support to ECMAScript (which include ActionScript, DMDScript, JavaScript, JScript). ... Sedna logo Sedna [1] is an open source XML database management system. ... XQuery is a programming language under development by the W3C thats designed to query collections of XML data. ... 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 syntax constraints imposed by XML itself. ... Document Type Definition (DTD), defined slightly differently within the XML and SGML (the language XML was derived from) specifications, is one of several SGML and XML schema languages, and is also the term used to describe a document or portion thereof that is authored in the DTD language. ... In computing, RELAX NG (REgular LAnguage for XML Next Generation) is a schema language for XML, based on Murata Makotos RELAX and James Clarks TREX. A RELAX NG schema specifies a pattern for the structure and content of an XML document. ... The Schematron is an XML structure validation language for making assertion about the presence or absence of patterns in trees. ... Document Schema Definition Languages (DSDL) is a framework within which multiple validation tasks of different types can be applied to an XML document in order to achieve more complete validation results than just the application of a single technology. ... We want fuses to be code black boxes that we can use without having to open them up to modify code for reuse. ... XML Certification Program (XML Master) is IT professional certifications for XML and related technologies. ... XRI (eXtensible Resource Identifier) is a scheme and resolution protocol for abstract identifiers compatible with Uniform Resource Identifiers and Internationalized Resource Identifiers, developed by the XRI Technical Committee at OASIS. The goal of XRIs is to provide a universal format for identifiers that are domain-, location-, application-, and transport-independent... XDI (XRI Data Interchange) is a generalized, extensible service for sharing, linking, and synchronizing data over the Internet and other data networks using XML documents and XRIs (Extensible Resource Identifiers). ... YAML (Rhymes with camel) (IPA pronunciation: ) is a human-readable data serialization format that takes concepts from languages such as XML, C, Python, Perl, as well as the format for electronic mail as specified by RFC 2822. ... XForms is two things: 1. ... The Extensible HyperText Markup Language, or XHTML, is a markup language that has the same depth of expression as HTML, but also conforms to XML syntax. ... The XML Linking Language, or XLink, is an XML markup language used for creating hyperlinks within XML documents. ... This page is a candidate for speedy deletion. ... XML Encryption is a specification that defines how to encrypt the content of an XML element. ... XML Information Set (Infoset) is a W3C recommendation. ... Hierarchy of objects in an example HTML DOM - Document Object Model The Document Object Model (DOM) is a platform- and language-independent standard object model for representing HTML or XML and related formats. ... XQuery is a query language (with some programming language features) that is designed to query collections of XML data. ... 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 syntax constraints imposed by XML itself. ... XML Signature (also called XMLDsig) is a W3C recommendation that defines an XML syntax for digital signatures. ... XPath (XML Path Language) is an expression language for addressing portions of an XML document, or for computing values (strings, numbers, or boolean values) based on the content of an XML document. ... XPointer is a system for addressing components of XML based internet media. ... The XML Protocol (XMLP) is a standard being developed by the W3C XML Protocol Working Group to the following guidelines, outlined in the groups charter: An envelope for encapsulating XML data to be transferred in an interoperable manner that allows for distributed extensibility. ... A collection of decorative soaps used for human hygiene purposes. ... The Web Services Description Language (WSDL) is an XML format published for describing Web services. ... Web services architecture The W3C defines a Web service (many sources also capitalize the second word, as in Web Services) as a software system designed to support interoperable Machine to Machine interaction over a network. ... The eXtensible Stylesheet Language (XSL) is a family of transformation languages which allows one to describe how files encoded in the XML standard are to be formatted or transformed. ... Linguistics Markup Language (LGML) is an XML-based framework for describing the syntax and semantics of natural languages. ...

Notes and references

  1. ^ More precisely, XML is a general-purpose specification for creating custom markup languages.
  2. ^ Bray, Tim; Jean Paoli, C. M. Sperberg-McQueen, Eve Maler, François Yergeau (September 2006). Extensible Markup Language (XML) 1.0 (Fourth Edition) - Origin and Goals. World Wide Web Consortium. Retrieved on October 29, 2006.
  3. ^ JSON and YAML are among other alternative text-based formats commonly described as lighter-weight and less verbose in comparison to XML. See Critique of XML in this article.
  4. ^ XHTML is an attempt to simplify and improve the consistency of HTML, which was based on SGML.
  5. ^ http://lists.xml.org/archives/xml-dev/200407/msg00208.html
  6. ^ Fitzgerald, Michael (2004). Learning XSLT. Sebastopol, CA: O'Reilly Media, p.243. ISBN 0-596-00327-7. 
  7. ^ Push, Pull, Next! by Bob DuCharme, at XML.com
  8. ^ http://java.sun.com/xml/jaxb/
  9. ^ http://www.cis.strath.ac.uk/research/snaque/
  10. ^ http://www.javaworld.com/javaworld/jw-03-2006/jw-0327-simplify.html
  11. ^ http://www.ximpleware.com/wp_SUN.pdf
  12. ^ http://www.javaworld.com/javaworld/jw-07-2006/jw-0724-vtdxml.html
  13. ^ http://vtd-xml.sf.net/persistence.html
  14. ^ Bray, Tim (February 2005). A conversation with Tim Bray: Searching for ways to tame the world’s vast stores of information. Association for Computing Machinery's "Queue site". Retrieved on April 16, 2006.
  15. ^ (1988) "Publishers, multimedia, and interactivity", {{{title}}}. Cobb Group. ISBN 1-55615-124-1. 
  16. ^ The working group was originally called the "Editorial Review Board." The original members and seven who were added before the first edition was complete, are listed at the end of the first edition of the XML Recommendation, at http://www.w3.org/TR/1998/REC-xml-19980210.
  17. ^ Reports From the W3C SGML ERB to the SGML WG And from the W3C XML ERB to the XML SIG
  18. ^ http://www.w3.org/TR/WD-xml-961114.html
  19. ^ Extensible Markup Language (XML) 1.1 (Second Edition) - Rationale and list of changes for XML 1.1. W3C. Retrieved on 2006-12-21.
  20. ^ Harold, Elliotte Rusty (2004). Effective XML. Addison-Wesley, 10-19. ISBN 0321150406. 
  21. ^ http://news.com.com/Small+company+makes+big+claims+on+XML+patents/2100-1014_3-5905949.html
  22. ^ http://blogs.zdnet.com/BTL/?p=2052
  23. ^ (See e.g., XML-QL Proposal discussing XML benefits, When to use XML, "XML Sucks" on c2.com, Daring to Do Less with XML)
  24. ^ Neal Ford, Language Oriented Programming, The Server Side's Java Symposium, 2007
  25. ^ Rusty, Elliotte (2002). Processing XML with Java(tm): a guide to SAX, DOM, JDOM, JAXP, and TrAX. Addison-Wesley. 0201771861. XML documents are too verbose compared with binary equivalents.
  26. ^ Rusty, Elliotte (2002). Xml in a Nutshell: A Desktop Quick Reference. O'Reilly. 0596002920.  XML documents are very verbose and searching is inefficient for high-performance largescale database applications.
  27. ^ However, the Binary XML effort strives to alleviate these problems by using a binary representation for the XML document. For example, the Java reference implementation of the Fast Infoset standard parsing speed is better by a factor 10 compared to Java Xerces, and by a factor 4 compared to the Piccolo driver, one of the fastest Java-based XML parser [1].
  28. ^ Bierman, Gavin (2005). Database Programming Languages: 10th international symposium, DBPL 2005 Trondheim, Norway. Springer. 3540309519. XML syntax is too verbose for human readers in for certain applications. Proposes a dual syntax for human readability.
  29. ^ Although many purportedly "less verbose" text formats actually cite XML as both inspiration and prior art. See e.g., http://yaml.org/spec/current.html, http://innig.net/software/sweetxml/index.html, http://www.json.org/xml.html.
  30. ^ For example, there is no provision for mandating that "3.14159" be a floating-point number rather than a seven-character string. Such conversions require processing. However, XML schema descriptions of XML documents add data-type support to XML processing.
  31. ^ Blanken, Henk M. (2003). Intelligent Search on Xml Data: Applications, Languages, Models, Implementations, and Benchmarks. Springer. 3540407685. Proposes a system for recognizing custom-defined data types.
  32. ^ A hierachical model only gives a fixed, monolithic view of the tree structure. For example, either actors under movies, or movies under actors, but not both.
  33. ^ Lim, Ee-Peng (2002). Digital Libraries: People, Knowledge, and Technology. Springer. 3540002618. Discusses some of the limitation with fixed hierarchy. Proceedings of the 5th International Conference on Asian Digitial Libraries, ICADL 2002, held in Singapore in December 2002.
  34. ^ Searle, Leroy F. (2004). Voice, text, hypertext: emerging practices in textual studies. University of Washington Press. 0295983051.  Proposes an alternative system for encoding overlapping elements.
  35. ^ (See e.g., http://www-128.ibm.com/developerworks/library/x-abolns.html )
  36. ^ The Myth of Self-Describing XML. Retrieved on 2007-05-12.
  37. ^ (See e.g., Use–mention distinction, Naming collision, Polysemy)

HTML, an initialism of Hypertext Markup Language, is the predominant markup language for web pages. ... Programming Perl is a classic OReilly book. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 355th day of the year (356th in leap years) in the Gregorian calendar. ... Binary XML, or Binary Extensible Markup Language, refers to any specification which attempts to encode an XML document in a binary data format, rather than plain text. ... “Java language” redirects here. ... Fast Infoset specifies a binary encoding for the XML Information Set. ... “Java language” redirects here. ... Xerces is a family of software packages for parsing and manipulating XML, part of the Apache XML project. ... This article or section is in need of attention from an expert on the subject. ... 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 syntax constraints imposed by XML itself. ... A tree structure is a way of representing the hierarchical nature of a structure in a graphical form. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 132nd day of the year (133rd in leap years) in the Gregorian calendar. ... The use–mention distinction is the distinction between using a word (or phrase, etc. ... A naming collision, an undesirable occurance in computer science, describes a situation in which multiple elements share names in a system demanding unique naming. ... Polysemy (from the Greek πολυσημεία = multiple meaning) is the capacity for a sign to have multiple meanings. ...

External links

Wikibooks
Wikibooks has more on the topic of
XML

Image File history File links Wikibooks-logo-en. ... Wikibooks logo Wikibooks, previously called Wikimedia Free Textbook Project and Wikimedia-Textbooks, is a wiki for the creation of books. ...

Specifications

Parsers

  • Expat free stream-oriented XML 1.0 parser library, written in C.
  • Libxml2 free XML C parser and toolkit.
  • RomXML Embedded XML commercial toolkit written in ANSI-C.
  • VTD-XML a next generation, open-source, XML parser/indexer available in C, C# and Java
  • XDOM open-source XML parser (and DOM and XPath implementation) in Delphi/Kylix.
  • XML resources at the Open Directory Project

Expat is a stream-oriented XML 1. ... The correct title of this article is . ... Virtual Token Descriptor for eXtensible Markup Language (VTD-XML) refers to a collection of efficient XML processing technologies centered around a non-extractive XML parsing technique called Virtual Token Descriptor (VTD). ... The Open Directory Project (ODP), also known as dmoz (from , its original domain name), is a multilingual open content directory of World Wide Web links owned by Netscape that is constructed and maintained by a community of volunteer editors. ...

Sources

Charles F. Goldfarb is known as the father of SGML, co-inventor of the concept of markup languages. ... Richard Alan Jelliffe (born 1960), commonly known as Rick Jelliffe, is an Australian programmer and standards activist (ISO, W3C, IETF), particularly associated with web standards, markup languages, internationalization and schema languages. ... Jon Bosak led the creation of the XML specification at the W3C. Tim Bray, who was one of the editors of the XML specification, has this to say in his note on Bosak in his annotated version of the spec: Jon Bosak is the single person without whose efforts XML...

Retrospectives

Jon Bosak led the creation of the XML specification at the W3C. Tim Bray, who was one of the editors of the XML specification, has this to say in his note on Bosak in his annotated version of the spec: Jon Bosak is the single person without whose efforts XML...

Papers

  • Lawrence A. Cunningham (2005). "Language, Deals and Standards: The Future of XML Contracts". Washington University Law Review. SSRN 900616. 

  Results from FactBites:
 
XML - Wikipedia, the free encyclopedia (4908 words)
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 constraints imposed by XML itself.
XML's regular structure and strict parsing rules allow software designers to leave parsing to standard tools, and since XML provides a general, data model-oriented framework for the development of application-specific languages, software designers need only concentrate on the development of rules for their data, at relatively high levels of abstraction.
XML 1.0 and XML 1.1 differ in the requirements of characters used for element and attribute names: XML 1.0 only allows characters which are defined in Unicode 2.0, which includes most world scripts, but excludes those which were added in later Unicode versions.
Extensible Markup Language (XML) 1.0 (Third Edition) (8474 words)
XML is an application profile or restricted form of SGML, the Standard Generalized Markup Language [ISO 8879].
XML documents are made up of storage units called entities, which contain either parsed or unparsed data.
XML provides a mechanism, the document type declaration, to define constraints on the logical structure and to support the use of predefined storage units.
  More results at FactBites »

 
 

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