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The extensible resource descriptor sequence ( XRDS ) is an XML-based file format that provides a list of services .

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56-553: The XML format used by XRDS was originally developed in 2004 by the OASIS XRI ( extensible resource identifier ) Technical Committee as the resolution format for XRIs. The acronym XRDS was coined during subsequent discussions between XRI TC members and OpenID developers at first Internet Identity Workshop held in Berkeley, CA in October 2005. The protocol for discovering an XRDS document from

112-539: A numeric character reference . Consider the Chinese character "中", whose numeric code in Unicode is hexadecimal 4E2D, or decimal 20,013. A user whose keyboard offers no method for entering this character could still insert it in an XML document encoded either as &#20013; or &#x4e2d; . Similarly, the string "I <3 Jörg" could be encoded for inclusion in an XML document as I &lt;3 J&#xF6;rg . &#0;

168-760: A URL was formalized as the Yadis specification published by Yadis.org in March 2006. Yadis became the service discovery format for OpenID 1.1. A common discovery service for both URLs and XRIs proved so useful that in November 2007 the XRI Resolution 2.0 specification formally added the URL-based method of XRDS discovery (Section 6). This format and discovery protocol subsequently became part of OpenID Authentication 2.0. In early 2008, work on OAuth discovery by Eran Hammer-Lahav led to

224-403: A RAND clause in its policy, welcomed the initiative and supposed OASIS will not continue using that policy as other companies involved would follow. The RAND policy has still not been removed and other commercial companies have not published such a free statement towards OASIS. Patrick Gannon, president and CEO of OASIS from 2001 to 2008, minimized the risk that a company could take advantage of

280-633: A blog post blaming Microsoft of involving people to improve and modify the accuracy of ODF and OpenXML Misplaced Pages articles. XML Extensible Markup Language ( XML ) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable . The World Wide Web Consortium 's XML 1.0 Specification of 1998 and several other related specifications —all of them free open standards —define XML. The design goals of XML emphasize simplicity, generality, and usability across

336-448: A list of syntax rules provided in the specification. Some key points in the fairly lengthy list include: The definition of an XML document excludes texts that contain violations of well-formedness rules; they are simply not XML. An XML processor that encounters such a violation is required to report such errors and to cease normal processing. This policy, occasionally referred to as " draconian error handling", stands in notable contrast to

392-522: A mechanism whereby an XML processor can reliably, without any prior knowledge, determine which encoding is being used. Encodings other than UTF-8 and UTF-16 are not necessarily recognized by every XML parser (and in some cases not even UTF-16, even though the standard mandates it to also be recognized). XML provides escape facilities for including characters that are problematic to include directly. For example: There are five predefined entities : All permitted Unicode characters may be represented with

448-546: A more compact non-XML syntax; the two syntaxes are isomorphic and James Clark 's conversion tool— Trang —can convert between them without loss of information. 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. Schematron

504-506: A rich datatyping system and allow for more detailed constraints on an XML document's logical structure. XSDs also use an XML-based format, which makes it possible to use ordinary XML tools to help process them. xs:schema element that defines a schema: RELAX NG (Regular Language for XML Next Generation) was initially specified by OASIS and is now a standard (Part 2: Regular-grammar-based validation of ISO/IEC 19757 – DSDL ). RELAX NG schemas may be written in either an XML based syntax or

560-472: A sequence of XRDs within a single XRDS document to reflect a chain of metadata about linked resources. XRDS documents can assert zero or more synonyms for a resource. In this context, a synonym is another identifier (a URI or XRI ) that identifies the same target resource. For instance, the example XRDS document above asserts four synonyms: For full details of XRDS synonym support, see XRI Resolution 2.0, Section 5. The other main purpose of XRDS documents

616-448: A sine-qua-non condition to access the consortium, and possibly jeopardize/boycott the standard if such a clause was not present. Doug Mahugh — while working for Microsoft (a promoter of Office Open XML , a Microsoft document format competing with OASIS's ISO/IEC 26300 , i.e. ODF v1.0) — claimed that "many countries have expressed frustration about the pace of OASIS's responses to defect reports that have been submitted on ISO/IEC 26300 and

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672-450: A standard to request royalties when it has been established, saying "If it's an option nobody uses, then what's the harm?" . Sam Hiser, former marketing lead of the now defunct OpenOffice.org , explained that such patents towards an open standard are counterproductive and inappropriate. He also argued that IBM and Microsoft were shifting their standardization efforts from the W3C to OASIS, in

728-421: A validity error must be able to report it, but may continue normal processing. A DTD is an example of a schema or grammar . Since the initial publication of XML 1.0, there has been substantial work in the area of schema languages for XML. Such schema languages typically constrain the set of elements that may be used in a document, which attributes may be applied to them, the order in which they may appear, and

784-527: A vocabulary to refer to the constructs within an XML document, but does not provide any guidance on how to access this information. A variety of APIs for accessing XML have been developed and used, and some have been standardized. Existing APIs for XML processing tend to fall into these categories: Stream-oriented facilities require less memory and, for certain tasks based on a linear traversal of an XML document, are faster and simpler than other alternatives. Tree-traversal and data-binding APIs typically require

840-503: A way to leverage probably their patents portfolio in the future. Hiser also attributed this RAND change to the OASIS policy to Microsoft. The RAND term could indeed allow any company involved to leverage their patent in the future, but that amendment was probably added in a way to attract more companies to the consortium, and encourage contributions from potential participants. Big actors like Microsoft could have indeed applied pressure and made

896-458: Is a lexical , event-driven API 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

952-726: Is a language for making assertions about the presence or absence of patterns in an XML document. It typically uses XPath expressions. Schematron is now a standard (Part 3: Rule-based validation of ISO/IEC 19757 – DSDL ). DSDL (Document Schema Definition Languages) is a multi-part ISO/IEC standard (ISO/IEC 19757) that 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

1008-570: Is an XML industry data standard. XML is used extensively to underpin various publishing formats. One of the applications of XML is in the transfer of Operational meteorology (OPMET) information based on IWXXM standards. The material in this section is based on the XML Specification . This is not an exhaustive list of all the constructs that appear in XML; it provides an introduction to the key constructs most often encountered in day-to-day use. XML documents consist entirely of characters from

1064-449: Is an example of an XRDS document for the fictional XRI i-name =example . This document would typically be requested from a Web server via HTTP or HTTPS using the content type application/xrds+xml . Note that the outer container <XRDS> element serves as a container for one or more <XRD> (Extensible Resource Descriptor) elements. Most simple XRDS documents have only one XRD. Other services like XRI resolution may construct

1120-454: Is an open public royalty-free OASIS specification. The OASIS XRI Technical Committee has operated since its inception in 2003 under a royalty-free licensing policy as stated in its charter and IPR page. OASIS (organization) The Organization for the Advancement of Structured Information Standards ( OASIS ; / oʊ ˈ eɪ . s ɪ s / ) is a nonprofit consortium that works on

1176-498: 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. Pull parsing treats the document as a series of items read in sequence using the iterator design pattern . 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

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1232-442: Is not permitted because the null character is one of the control characters excluded from XML, even when using a numeric character reference. An alternative encoding mechanism such as Base64 is needed to represent such characters. Comments may appear anywhere in a document outside other markup. Comments cannot appear before the XML declaration. Comments begin with <!-- and end with --> . For compatibility with SGML ,

1288-417: Is to assert the services associated with a resource, called service endpoints or SEPs . For instance, the example XRDS document above asserts four service endpoints for the represented resource: For full details of XRDS service endpoints, see XRI Resolution 2.0, Sections 4.2 and 13. In XRDS documents, a service is identified using a URI or XRI . Following are listings of well-known service types. XRDS

1344-504: The Internet . It is a textual data format with strong support via Unicode for different human languages . Although the design of XML focuses on documents, the language is widely used for the representation of arbitrary data structures , such as those used in web services . Several schema systems exist to aid in the definition of XML-based languages, while programmers have developed many application programming interfaces (APIs) to aid

1400-453: The Unicode repertoire. Except for a small number of specifically excluded control characters , any character defined by Unicode may appear within the content of an XML document. XML includes facilities for identifying the encoding of the Unicode characters that make up the document, and for expressing characters that, for one reason or another, cannot be used directly. Unicode code points in

1456-410: The infoset augmentation facility and attribute defaults. RELAX NG and Schematron intentionally do not provide these. A cluster of specifications closely related to XML have been developed, starting soon after the initial publication of XML 1.0. It is frequently the case that the term "XML" is used to refer to XML together with one or more of these other technologies that have come to be seen as part of

1512-429: The XML core. Some other specifications conceived as part of the "XML Core" have failed to find wide adoption, including XInclude , XLink , and XPointer . The design goals of XML include, "It shall be easy to write programs which process XML documents." Despite this, the XML specification contains almost no information about how programmers might go about doing such processing. The XML Infoset specification provides

1568-549: The XML processor inserts in the DTD itself and in the XML document wherever they are referenced, like character escapes. DTD technology is still used in many applications because of its ubiquity. A newer schema language, described by the W3C as the successor of DTDs, is XML Schema , often 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

1624-541: The adoption of SGML through mainly educational activities, though some amount of technical activity was also pursued including an update of the CALS Table Model specification and specifications for fragment interchange and entity management. In 1998, with the movement of the industry to XML , SGML Open changed its emphasis from SGML to XML, and changed its name to OASIS Open to be inclusive of XML and reflect an expanded scope of technical work and standards. The focus of

1680-434: The allowable parent/child relationships. The oldest schema language for XML is the document type definition (DTD), inherited from SGML. DTDs have the following benefits: DTDs have the following limitations: Two peculiar features that distinguish DTDs from other schema types are the syntactic support for embedding a DTD within XML documents and for defining entities , which are arbitrary fragments of text or markup that

1736-598: The base language for communication protocols such as SOAP and XMPP . It is one of the message exchange formats used in the Asynchronous JavaScript and XML (AJAX) programming technique. Many industry data standards, such as Health Level 7 , OpenTravel Alliance , FpML , MISMO , and National Information Exchange Model are based on XML and the rich features of the XML schema specification. In publishing, Darwin Information Typing Architecture

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1792-401: The behavior of programs that process HTML , which are designed to produce a reasonable result even in the presence of severe markup errors. XML's policy in this area has been criticized as a violation of Postel's law ("Be conservative in what you send; be liberal in what you accept"). The XML specification defines a valid XML document as a well-formed XML document which also conforms to

1848-423: The case of C1 characters, this restriction is a backwards incompatibility; it was introduced to allow common encoding errors to be detected. The code point U+0000 (Null) is the only character that is not permitted in any XML 1.1 document. The Unicode character set can be encoded into bytes for storage or transmission in a variety of different ways, called "encodings". Unicode itself defines encodings that cover

1904-443: The consortium requires some fees to be paid, which must be renewed annually, depending on the membership category adherents want to access. Among the adherents are members from Dell , IBM , ISO/IEC , Cisco Systems , KDE e.V. , Microsoft , Oracle , Red Hat , The Document Foundation , universities, government agencies, individuals and employees from other less-known companies. Member sections are special interest groups within

1960-454: The consortium that focus on specific topics. These sections keep their own distinguishable identity and have full autonomy to define their work program and agenda. The integration of the member section in the standardization process is organized via the technical committees. Active member sections are for example: Member sections may be completed when they have achieved their objectives. The standards that they promoted are then maintained by

2016-472: The consortium's activities also moved from promoting adoption (as XML was getting much attention on its own) to developing technical specifications. In July 2000 a new technical committee process was approved. With the adoption of the process the manner in which technical committees were created, operated, and progressed their work was regularized. At the adoption of the process there were five technical committees; by 2004 there were nearly 70 . During 1999, OASIS

2072-429: The data structure and contain metadata . What is within the tags is data, encoded in the way the XML standard specifies. An additional XML schema (XSD) defines the necessary metadata for interpreting and validating XML. (This is also referred to as the canonical schema.) An XML document that adheres to basic XML rules is "well-formed"; one that adheres to its schema is "valid." IETF RFC 7303 (which supersedes

2128-471: The development of XRDS Simple, a profile of XRDS that restricts it to the most basic elements and introduces some extensions to support OAuth discovery and other protocols that use specific HTTP methods. In late 2008, XRDS Simple has been cancelled and merged back into the main XRDS specification resulting in the upcoming XRD 1.0 format. Besides XRI resolution, examples of typical XRDS usage include: Following

2184-456: The development, convergence, and adoption of projects - both open standards and open source - for Computer security , blockchain , Internet of things (IoT), emergency management , cloud computing , legal data exchange , energy , content technologies , and other areas. OASIS was founded under the name "SGML Open" in 1993. It began as a trade association of Standard Generalized Markup Language (SGML) tool vendors to cooperatively promote

2240-442: The direct use of almost any Unicode character in element names, attributes, comments, character data, and processing instructions (other than the ones that have special symbolic meaning in XML itself, such as the less-than sign, "<"). The following is a well-formed XML document including Chinese , Armenian and Cyrillic characters: The XML specification defines an XML document as a well-formed text, meaning that it satisfies

2296-516: The entire repertoire; well-known ones include UTF-8 (which the XML standard recommends using, without a BOM ) and UTF-16 . There are many other text encodings that predate Unicode, such as ASCII and various ISO/IEC 8859 ; their character repertoires are in every case subsets of the Unicode character set. XML allows the use of any of the Unicode-defined encodings and any other encodings whose characters also appear in Unicode. XML also provides

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2352-498: The following ranges are valid in XML 1.0 documents: XML 1.1 extends the set of allowed characters to include all the above, plus the remaining characters in the range U+0001–U+001F. At the same time, however, it restricts the use of C0 and C1 control characters other than U+0009 (Horizontal Tab), U+000A (Line Feed), U+000D (Carriage Return), and U+0085 (Next Line) by requiring them to be written in escaped form (for example U+0001 must be written as &#x01; or its equivalent). In

2408-685: The functions performing the parsing, or passed down (as function parameters) into lower-level functions, or returned (as function return values) to higher-level functions. Examples of pull parsers include Data::Edit::Xml in Perl , StAX in the Java programming language, XMLPullParser in Smalltalk , XMLReader in PHP , ElementTree.iterparse in Python , SmartXML in Red , System.Xml.XmlReader in

2464-541: The inability for SC 34 members to participate in the maintenance of ODF." However, Rob Weir, co-chair of the OASIS ODF Technical Committee noted that at the time, "the ODF TC had received zero defect reports from any ISO/IEC national body other than Japan". He added that the submitter of the original Japanese defect report, Murata Mokoto, was satisfied with the preparation of the errata. He also self-published

2520-550: The older RFC 3023 ), provides rules for the construction of media types for use in XML message. It defines three media types: application/xml ( text/xml is an alias), application/xml-external-parsed-entity ( text/xml-external-parsed-entity is an alias) and application/xml-dtd . They are used for transmitting raw XML files without exposing their internal semantics . RFC 7303 further recommends that XML-based languages be given media types ending in +xml , for example, image/svg+xml for SVG . Further guidelines for

2576-449: The possibility of free / open source implementations of these standards. Further, contributors could initially offer royalty-free use of their patent, later imposing per-unit fees, after the standard has been accepted. On April 11, 2005, The New York Times reported IBM committed, for free, all of its patents to the OASIS group. Larry Rosen, a software law expert and the leader of the reaction which rose up when OASIS quietly included

2632-449: The processing of XML data. The main purpose of XML is serialization , i.e. storing, transmitting, and reconstructing arbitrary data. For two disparate systems to exchange information, they need to agree upon a file format. XML standardizes this process. It is therefore analogous to a lingua franca for representing information. As a markup language , XML labels, categorizes, and structurally organizes information. XML tags represent

2688-534: The relevant technical committees directly within OASIS. For example: Like many bodies producing open standards e.g. ECMA , OASIS added a Reasonable and non-discriminatory licensing (RAND) clause to its policy in February 2005. That amendment required participants to disclose intent to apply for software patents for technologies under consideration in the standard. Contrary to the W3C , which requires participants to offer royalty-free licenses to anyone using

2744-551: The resulting standard, OASIS offers a similar Royalty Free on Limited Terms mode, along with a Royalty Free on RAND Terms mode and a RAND (reasonable and non-discriminatory) mode for its committees. Compared to W3C, OASIS is less restrictive regarding obligation to companies to grant a royalty-free license to the patents they own. Controversy has rapidly arisen because this licensing was added silently and allows publication of standards which could require licensing fee payments to patent holders. This situation could effectively eliminate

2800-487: The rules of a Document Type Definition (DTD). In addition to being well formed, an XML document may be valid . This means that it contains a reference to a Document Type Definition (DTD), and that its elements and attributes are declared in that DTD and follow the grammatical rules for them that the DTD specifies. XML processors are classified as validating or non-validating depending on whether or not they check XML documents for validity. A processor that discovers

2856-469: The string "--" (double-hyphen) is not allowed inside comments; this means comments cannot be nested. The ampersand has no special significance within comments, so entity and character references are not recognized as such, and there is no way to represent characters outside the character set of the document encoding. An example of a valid comment: <!--no need to escape <code> & such in comments--> XML 1.0 (Fifth Edition) and XML 1.1 support

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2912-719: The two organizations and to coordinate the completion of the work through a coordinating committee. In 2004 OASIS submitted its completed ebXML specifications to ISO TC154 where they were approved as ISO 15000 . The consortium has its headquarters in Woburn, Massachusetts , shared with other companies. In December 2020, OASIS moved to its current location, 400 TradeCenter Drive. Previous office locations include 25 Corporate Drive Suite 103 and 35 Corporate Drive, Suite 150, both in Burlington, MA. The following standards are under development or maintained by OASIS technical committees: Adhesion to

2968-522: The use of XML in a networked context appear in RFC 3470 , also known as IETF BCP 70, a document covering many aspects of designing and deploying an XML-based language. XML has come into common use for the interchange of data over the Internet. Hundreds of document formats using XML syntax have been developed, including RSS , Atom , Office Open XML , OpenDocument , SVG , COLLADA , and XHTML . XML also provides

3024-472: The use of much more memory, but are often found more convenient for use by programmers; some include declarative retrieval of document components via the use of XPath expressions. XSLT is designed for declarative description of XML document transformations, and has been widely implemented both in server-side packages and Web browsers. XQuery overlaps XSLT in its functionality, but is designed more for searching of large XML databases . Simple API for XML (SAX)

3080-426: 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 . 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

3136-522: Was approached by UN/CEFACT , the committee of the United Nations dealing with standards for business, to jointly develop a new set of specifications for electronic business. The joint initiative, called " ebXML " and which first met in November 1999, was chartered for a three-year period. At the final meeting under the original charter, in Vienna, UN/CEFACT and OASIS agreed to divide the remaining work between

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