![]() An example is, where the names of the attributes are "src" and "alt", and their values are "madonna.jpg" and "Madonna" respectively. Īttribute An attribute is a markup construct consisting of a name–value pair that exists within a start-tag or empty-element tag. The characters between the start-tag and end-tag, if any, are the element's content, and may contain markup, including other elements, which are called child elements. Tags come in three flavors:Įlement An element is a logical document component that either begins with a start-tag and ends with a matching end-tag or consists only of an empty-element tag. Tag A tag is a markup construct that begins with. In addition, whitespace before and after the outermost element is classified as markup. However, in a CDATA section, the delimiters are classified as markup, while the text between them is classified as content. Strings of characters that are not markup are content. Generally, strings that constitute markup either begin with the character, or they begin with the character & and end with a. Markup and content The characters making up an XML document are divided into markup and content, which may be distinguished by the application of simple syntactic rules. The processor (as the specification calls it) is often referred to colloquially as an XML parser. The specification places requirements on what an XML processor must do and not do, but the application is outside its scope. Processor and application The processor analyzes the markup and passes structured information to an application. Almost every legal Unicode character may appear in an XML document. 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.Ĭharacter An XML document is a string of characters. The material in this section is based on the XML Specification. Further guidelines for 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. RFC 7303 also recommends that XML-based languages be given media types ending in +xml for example image/svg+xml for SVG. It also defines the media types application/xml and text/xml, which say only that the data is in XML, and nothing about its semantics. ![]() IETF RFC:3023, now superseded by RFC:7303, gave rules for the construction of Internet Media Types for use when sending XML. XML has come into common use for the interchange of data over the Internet. This is also referred to as the canonical schema. The message exchange format is standardised as an XML schema (XSD). Disparate systems communicate with each other by exchanging XML messages. XML is widely used in a Service-oriented architecture (SOA). XML is used extensively to underpin various publishing formats. In publishing, Darwin Information Typing Architecture is an XML industry data standard. Many of these standards are quite complex and it is not uncommon for a specification to comprise several thousand pages. 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. NET Framework use XML files for configuration, and property lists are an implementation of configuration storage built on XML. XML has also provided the base language for communication protocols such as XMPP. XML-based formats have become the default for many office-productivity tools, including Microsoft Office ( Office Open XML), and LibreOffice ( OpenDocument), and Apple's iWork. Hundreds of document formats using XML syntax have been developed, including RSS, Atom, SOAP, SVG, and XHTML. The essence of why extensible markup languages are necessary is explained at Markup language (for example, see Markup language § XML) and at Standard Generalized Markup Language. 8.2.3 Valid Unicode characters in XML 1.0 and XML 1.1.4 Syntactical correctness and error-handling.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. 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. It is a textual data format with strong support via Unicode for different human languages. The design goals of XML emphasize simplicity, generality, and usability across the Internet. 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. Extensible Markup Language ( XML) is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable.
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