A sitemap is a list of pages of a web site within a domain .
59-464: There are three primary kinds of sitemap: Sitemaps may be addressed to users or to software. Many sites have user-visible sitemaps which present a systematic view, typically hierarchical, of the site. These are intended to help visitors find specific pages, and can also be used by crawlers. They also act as a navigation aid by providing an overview of a site's content at a single glance. Alphabetically organized sitemaps, sometimes called site indexes, are
118-539: 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 中 or 中 . Similarly, the string "I <3 Jörg" could be encoded for inclusion in an XML document as I <3 Jörg . �
177-504: A different approach. For use by search engines and other crawlers, there is a structured format, the XML Sitemap, which lists the pages in a site, their relative importance, and how often they are updated. This is pointed to from the robots.txt file and is typically called sitemap.xml . The structured format is particularly important for websites which include pages that are not accessible through links from other pages, but only through
236-448: 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 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
295-412: A file, these two work together as follows: mime.types associates an extension with a MIME type, while mailcap associates a MIME type with a program. In UNIX-type systems, the mime.types file is usually located at /etc/ mime.types and/or $ HOME/ .mime.types and the format is simply that each line is a space-delimited list of a MIME type, followed by zero or more extensions. For example,
354-448: 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
413-522: 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
472-470: A media format, but it may or must also contain other content, such as a tree prefix, producer, product or suffix, according to the different rules in registration trees. All media types should be registered using the IANA registration procedures. For the efficiency and flexibility of the media type registration process, different structures of subtypes can be registered in registration trees that are distinguished by
531-405: A media type. XDG specifications implemented by Linux desktop environments continue to use the term "MIME type". A media type consists of a type and a subtype , which is further structured into a tree . A media type can optionally define a suffix and parameters : As an example, an HTML file might be designated text/html; charset=UTF-8 . In this example, text is the type, html
590-546: 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
649-504: 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
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#1732855967060708-424: A registration done by a third party. The personal or vanity tree includes media types associated with non publicly available products or experimental media types. It uses the prs. tree prefix. Examples are audio/prs.sid , image/prs.btif . The unregistered tree includes media types intended exclusively for use in private environments and only with the active agreement of the parties exchanging them. It uses
767-506: 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
826-421: 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
885-527: 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
944-412: 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
1003-726: 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
1062-570: 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
1121-404: 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 the use of XML in
1180-404: Is an example of a validated XML sitemap for a simple three-page website. Sitemaps are a useful tool for making sites searchable, particularly those written in non-HTML languages. 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
1239-498: 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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#17328559670601298-455: 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 the Internet . It is a textual data format with strong support via Unicode for different human languages . Although
1357-401: Is defined by RFC 1524 "A User Agent Configuration Mechanism for Multimedia Mail Format Information" but is not defined as an Internet standard. It is supported by most Unix systems. Lines can be comments starting with the # character, or a mime-type followed by how to handle that mime type. An associated file is the mime.types file, which associates filename extensions with a MIME type . If
1416-442: 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 ,
1475-500: Is the subtype, and charset=UTF-8 is an optional parameter indicating the character encoding. Types, subtypes, and parameter names are case-insensitive. Parameter values are usually case-sensitive, but may be interpreted in a case-insensitive fashion depending on the intended use. The "type" part defines the broad use of the media type. As of November 1996, the registered types were: application , audio , image , message , multipart , text and video . By July 2024,
1534-698: The x. tree prefix. Examples are application/x.foo , video/x.bar . Media types in this tree cannot be registered. This type was originally defined in RFC 1590 (published in September 1993) using the x- or X- prefix. RFC 2048 (published in November 1996) introduced the x. prefix, but discouraged use of the unregistered tree, as new personal and vendor trees with relaxed registration requirements are now available. The current RFC 6838 (published in January 2013) maintains
1593-497: The .NET Framework , and the DOM traversal API (NodeIterator and TreeWalker). Media type In information and communications technology , a media type , content type or MIME type is a two-part identifier for file formats and content formats . Their purpose is comparable to filename extensions and uniform type identifiers , in that they identify the intended data format. They are mainly used by technologies underpinning
1652-604: The Internet , and also used on Linux desktop systems. The Internet Assigned Numbers Authority (IANA) is the official authority for the standardization and publication of these classifications. Media types were originally defined in Request for Comments RFC 2045 (MIME) Part One: Format of Internet Message Bodies (Nov 1996) in November 1996 as a part of the MIME (Multipurpose Internet Mail Extensions) specification, for denoting type of email message content and attachments; hence
1711-453: 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
1770-410: 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
1829-450: The IESG, be registered in the standards tree with its unprefixed subtype. application/x-www-form-urlencoded is an example of a widely deployed type that ended up registered with the x- prefix. Suffix is an augmentation to the media type definition to additionally specify the underlying structure of that media type, allowing for generic processing based on that structure and independent of
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1888-481: The MIME type is properly set, this is unnecessary, but MIME types may be incorrectly set, or set to a generic type such as application/octet-stream , and mime.types allows one to fall back on the extension in these cases. Similarly, since many file systems do not store MIME type information, but instead rely on the filename extension, a mime.types file is frequently used by web servers to determine MIME type. When viewing
1947-454: The Sitemaps protocol. Since the major search engines use the same protocol, having a Sitemap lets them have the updated page information. Sitemaps do not guarantee all links will be crawled, and being crawled does not guarantee indexing. Google Webmaster Tools allow a website owner to upload a sitemap that Google will crawl, or they can accomplish the same thing with the robots.txt file. Below
2006-429: 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
2065-549: 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
2124-434: 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
2183-598: 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
2242-401: 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
2301-423: 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
2360-463: The context. Industry consortia as well as non-commercial entities can register media types in the vendor tree. A registration in the vendor tree may be created by anyone who needs to interchange files associated with some software product or set of products. However, the registration belongs to the vendor or organization producing the software that employs the type being registered, and that vendor or organization can at any time elect to assert ownership of
2419-546: 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 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
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2478-442: 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
2537-516: 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
2596-424: The exact type's particular semantics. Media types that make use of a named structured syntax should use the appropriate IANA registered "+"suffix for that structured syntax when they are registered. Unregistered suffixes should not be used (since January 2013). Structured syntax suffix registration procedures are defined in RFC 6838. The +xml suffix has been defined since January 2001 (RFC 3023 ), and
2655-498: 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  or its equivalent). In
2714-685: 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
2773-426: 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 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
2832-460: The original name, MIME type . Media types are also used by other internet protocols such as HTTP , document file formats such as HTML , and the XDG specifications implemented by Linux desktop environments , for similar purposes. Different internet standards or web standards bodies differ on the preferred term for this type of identifier. The IANA and IETF use the term "media type", and consider
2891-661: The registered types included the foregoing, plus font , example , model , and haptics . An unofficial top-level type in common use is chemical , used for chemical file formats . In the context of Linux desktop environments , the unofficial top-level types inode ( inodes other than normal files, such as filesystem directories , device files or symbolic links ), x-content ( removable media , such as x-content/image-dcf for DCF digital cameras ), package ( package manager packages) and x-office (generic categories of office productivity software document) are used. A subtype typically consists of
2950-487: 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
3009-410: The same recommendation, but subtypes prefixed with x- or X- are no longer considered to be members of this tree. Media types that have been widely deployed (with a subtype prefixed with x- or X- ) without being registered, should be, if possible, re-registered with a proper prefixed subtype. If this is not possible, the media type can, after an approval by both the media types reviewer and
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#17328559670603068-571: The site's search tools or by dynamic construction of URLs in JavaScript . Google introduced the Sitemaps protocol so web developers can publish lists of links from across their sites. The basic premise is that some sites have a large number of dynamic pages that are only available through the use of forms and user entries. The Sitemap files contain URLs to these pages so that web crawlers can find them. Bing , Google, Yahoo and Ask now jointly support
3127-440: The standards tree must be either associated with IETF specifications approved directly by the IESG, or registered by an IANA recognized standards-related organization. The vendor tree includes media types associated with publicly available products. It uses the vnd. tree prefix. Examples are: application/vnd.ms-excel , application/vnd.oasis.opendocument.text . The terms "vendor" and "producer" are considered equivalent in
3186-469: 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
3245-572: The term "MIME type" to be obsolete, since media types have become used in contexts unrelated to email, such as HTTP. By contrast, the WHATWG continues to use the term "MIME type" and discourages use of the term "media type" as ambiguous, since it is used with a different meaning in connection with the CSS @media feature. The HTTP response header for providing the media type is Content-Type . The W3C has used ContentType as an XML data-type name for
3304-472: 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)
3363-581: The use of tree prefixes. Currently the following trees are created: standard (no prefix), vendor ( vnd. prefix), personal or vanity ( prs. prefix), unregistered ( x. prefix). These registration trees were first defined in November 1996 (obsoleted RFC 2048 - currently RFC 6838). New registration trees may be created by IETF Standards Action for external registration and management by well-known permanent organizations (e.g. scientific societies). The standards tree does not use any tree prefix. Examples are text/javascript , image/png . Registrations in
3422-426: 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
3481-606: Was formally included in the initial contents of the Structured Syntax Suffix Registry along with +json , +ber , +der , +fastinfoset , +wbxml , and +zip in January 2013 (RFC 6839). Subsequent additions include +gzip , +cbor , +json-seq , and +cbor-seq . From the IANA registry: Mailcap (derived from the phrase "mail capability") is a type of meta file used to configure how MIME-aware applications such as mail clients and web browsers render files of different MIME-types. The mailcap format
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