Quick Start to XML, a classic introduction to xml

Quick Start to XML, a classic introduction to xml

What is XML?

Extensible Markup Language

Custom tags;

Used to transmit data;

Extensible Markup Language is a markup language similar to hypertext markup language.

Comparison with HTML:

1. It is not used to replace HTML;

XML is a supplement to HTML

2. Different purposes

HTML displays data, and XML contains and transmits data.

3. different syntaxes

Not all HTML tags appear in pairs. XML must appear in pairs and be case sensitive.

* Syntax rules to be followed for well-formatted XML:

1) The root element must exist.

2) tags must be disabled.

3) mark case sensitive

4) elements must be correctly nested.

5) The attribute must be enclosed in quotation marks.

XML specifications-DTD and Schema

1. DTD

Document Type Definition

Defines the file structure and provides syntax rules. You can choose to use the structure.

Usage: built-in and external calls.

2. Schema

It also describes the structure of the document and replaces the DTD, which is more powerful than the DTD.

Protects data communication.

<? Xml version = "1.0" encoding = "gb2312"?> <! -- Declaration --> <! DOCTYPE personal SYSTEM "staff. dtd"> <! -- Call the DTD file --> <personal> <! -- Root element --> <department id = "Marketing department"> <! -- Sub-element --> <employee> <name> Dan </name> <title> Manager </title> <staff> </employee> <name> Amy </name> <title> employee </title> <staff> </employee> </department> <department id = "Marketing department"> <employee> <name> Jena </name> <title> Manager </title> </employee> <name> Sarah </name> <title> employee </title> </employee> </department> </personal>

Document Tree

XML is just getting started. Like HTML, I just learned something. You also need to learn more and practice more. After practice, we can gain a deeper understanding of the role of XML and its unique functions.