Simple XML tutorial (1)

Simple XML tutorial
I. Background and application prospects of XML
(1) origin
XML (eXtended Markup Language) evolved from SGML (Standard Generalized Markup Language). Originally, SGML was designed to solve
Files and their formats are a markup language, so they are very complicated and difficult to use. At that time, the application level of computers was still at a very low stage, and people only needed to pass
And display some simple data. Therefore, in, Tim Berners-lee developed a HyperText format based on SGML, called HTML (HyperText Markup Language ),
Very simple. When the application level of the computer is also greatly improved, people are already dissatisfied with the HTML that is too simple, so they began to modify and upgrade it,
In this way, HTML has been upgraded from 1.0 to 4.0, and many commands have been extended. In fact, HTML is designed to solve more problems, but because of the defects of HTML
To solve more problems, will simple HTML be converted into a very complex and hard-to-understand language? Even if you look at an HTML source file, it will be several times bigger,
In addition, HTML stores the data and display format together. If we only want to use the data without the format, we can imagine how difficult it is to separate the data and format.
With the development of the Internet, W3C announced the XML1.0 version in January, and immediately became an important milestone in computer history.
XML includes XML metadata files, Schema files, XSLT display files, XLL links, Xpath, and other related parts. However, XML is not a computer professional.
For people, it is best to read only its metadata file and hand over other problems to developers and producers, so that non-professionals can get away from the pain of understanding the headaches of the terms.
. Here we will talk about the characteristics of XML:
1. Electronic data exchange (EDI)
2. Flexible development
Because XML is designed for separation of data and format, XML metadata files are pure data files, so that you can use the same data source to display multiple styles.
. When HTML is used, every time a style is displayed, it is very painful to mix the data and format together.
The tags used in XML are defined by ourselves, which greatly improves the readability of our data files and is no longer limited to standard tags of HTML files. And because