XML
ExtensibleMarkup language,A subset of the Standard Universal Markup Language, a markup language used to mark electronic documents to make them structural
Extensible Markup Language is a meta-markup language that defines a structured markup language used to define semantics related to other specific fields. These markup languages divide documents into components and identify these components. XML Document definition methods include: document type definition (DTD) and XML Schema. DTD defines the overall structure of the document and the syntax of the document. It is widely used and supported by rich tools. XML Schema is used to define more powerful and rich features such as management information. XML enables more precise declaration of content, facilitating more meaningful search results across multiple platforms. It provides a format for describing structured data, simplifies data exchange and representation in the network, separates code, data and representation, and serves as a standard format for data exchange, so it Often referred to as smart data documents.
1. What is extensible markup language?
Extensible Markup Language is a markup language that is very similar to
.
#It is designed to transmit data, not display data.Its tags are not predefined. You need to define the labels yourself.
#It is designed to be self-descriptive.
#It is a recommended standard by W3C.
## 2.
Hypertext Markup Language The difference between It is not a replacement for Hypertext Markup Language
. It is a supplement to Hypertext Markup Language.
It is designed for different purposes than Hypertext Markup Language:
It is designed to transmit and When storing data, the focus is on the content of the data.
Hypertext Markup Language is designed to display data, with the focus being on the appearance of the data.
# Hypertext markup language is designed to display information, while it is designed to transmit information.
The best description of it is: it is an information transmission tool independent of software and hardware.
3. Extensible Markup Language is a recommended standard by W3C
##XML became a W3C
recommendation on February 10, 1998.
4. Extensible Markup Language is everywhere
Super Text markup language.
XML is the most commonly used tool for data transfer between various applications.
XML consists of 3 parts, which are: Document Type Definition (DTD), which is the layout language of XML; Extensible Style Language (XSL), which is the layout language of XML. Style sheet language; and Extensible Link Language (XLL).
（1）DTD
DTD specifies the logical structure of the document. It defines the syntax of the document, and the syntax of the document in turn allows XML parsers to confirm the legality of the use of page tags. DTD defines the elements of the page, the attributes of the elements, and the relationship between elements and attributes. Elements are delimited by a start tag and an end tag. For empty elements, an empty element tag is used to separate them. Each element has a type identified by a name, also known as its universal identifier, and it can also have a set of attribute specifications. Each property description has a name and a value. Ideally the definition should be oriented towards describing the data structures relevant to the application, rather than how to display the data. That is, you should define an element as a header row, and then let the stylesheet and script definition display the header row.
DTD is not mandatory. For simple applications, developers do not need to create their own DTD and can use predefined public DTDs or not. Even if a document already has a DTD, as long as the document organization is good, the syntax parser does not need to check the legality of the document against the DTD. The server may have already performed the check, so check time and bandwidth will be greatly saved.
(2) XSL
XSL is used A language that specifies the style of XML documents. XSL enables Web browsers to change the representation of the original document, such as changing the display order of data, without having to interact with the server. Through the transformation of the style sheet, the same document can be displayed larger, or folded to show only the outer layer, or changed to print format.
XSL relies on its own scalability to control endless tags, and the ways to control each tag are also endless, which also provides advanced layout features for the Web . Such as text rotation, multiple columns and independent areas. International writing formats are also supported, allowing you to mix left-to-right, right-to-left and top-to-bottom writing formats on one page. Just as XML is between HTML and SGML, the XSL standard is between the document style semantics and specification languages of CSS and SGMI.
（3）XLL
XLL supports existing simple links on the Web, and will further expand links, including indirect links that terminate dead links and the ability to query only the relevant parts of a certain element from the server Links etc.
All specifications and technologies of Web Service are based on XML as the underlying core and architectural foundation Yes, for Web Services, SOAP, WSDL and UDDI all use XML as a standard means of information description and exchange. The emergence of XML technology has promoted the emergence and development of Web Service technology.
| XHTML▪ HTML 5▪ CSS▪ TCP/IP |
|---|
| Multimedia | SMIL▪ SVG |
|---|
| ▪ HTML ▪ XHTML ▪ XML ▪ XForms ▪ DHTML |
|---|
| ▪ Cascading Style Sheets▪ XSL |
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| ▪ CGI ▪ FastCGI ▪ ASP ▪ ASP.NET ▪ ColdFusion ▪ JSP ▪ PHP |
|---|
| ▪ ActiveX ▪ Java Applet ▪ JavaFX ▪ AJAX ▪ Silverlight ▪ ActionScript ▪ Flex ▪ AIR |
|---|
| ▪ JavaScript ▪ JScript ▪ VBScript ▪ ECMAScript |
|---|
| ▪ URL ▪ URI ▪ XPath ▪ URL Rewriting |
|---|
| ▪ DTD ▪ XML Schema |
|---|
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