1. Background of XML generation
Like HTML, XML comes from Standard Generalized Markup Language, which is the standard general markup language, referred to as SGML. SGML has existed long ago before the Web was invented. As its name states, SGML is a common language for describing document materials using tags. It contains a series of document type definitions (DTD for short). The meaning of tags is defined in DTD, so the syntax of SGML can be extended. SGML is very large, not easy to learn or use, and it is also very difficult to implement on computers. In view of these factors, researchers from the inventor of the Web, the CERN, proposed the HTML language based on the capabilities of computer technology at that time (1989).
HTML uses only a small part of the tags in SGML. For example, HTML 3.2 defines 70 types of tags. For ease of implementation on a computer, the HTML stipulated tag is fixed, that is, the HTML syntax is not extensible, and it does not need to include DTD. HTML, a fixed syntax, makes it easy to learn and use, and it is also very easy to develop HTML browsers on computers. It is precisely because of the simplicity of HTML that Web technology has moved from the computer industry to the whole society and to thousands of households, and the development of the Web is at its peak.
In recent years, as the application of the Web becomes more and more extensive and in-depth, people gradually feel that HTML is not enough, and the overly simple syntax of HTML has seriously hindered the use of it to express complex forms. Although HTML has launched new versions after new versions and has already expressed functions such as scripts, tables, and frames, it has never been able to meet the growing demand. On the other hand, computer technology has also developed very rapidly in recent years, and it can already realize a much more complex web browser than when HTML was invented and created. Therefore, it is necessary and possible to develop a new Web page language.
Some people suggest using SGML directly as the web language, which can certainly solve the difficulties encountered in HTML. However, SGML is too huge, and it is not easy to learn and use users. It is very difficult to fully implement SGML browsers, so we naturally think that only a subset of SGML will make the new language both convenient to use and easy to implement. It is in this situation that the Web Standardization Organization W3C recommends a streamlined version of SGML - XML came into being.
Like HTML, XML comes from Standard Generalized Markup Language, which is the standard general markup language, referred to as SGML. SGML has existed long ago before the Web was invented. As its name states, SGML is a common language for describing document materials using tags. It contains a series of document type definitions (DTD for short). The meaning of tags is defined in DTD, so the syntax of SGML can be extended. SGML is very large, not easy to learn or use, and it is also very difficult to implement on computers. In view of these factors, researchers from the inventor of the Web, the CERN, proposed the HTML language based on the capabilities of computer technology at that time (1989).
HTML uses only a small part of the tags in SGML. For example, HTML 3.2 defines 70 types of tags. For ease of implementation on a computer, the HTML stipulated tag is fixed, that is, the HTML syntax is not extensible, and it does not need to include DTD. HTML, a fixed syntax, makes it easy to learn and use, and it is also very easy to develop HTML browsers on computers. It is precisely because of the simplicity of HTML that Web technology has moved from the computer industry to the whole society and to thousands of households, and the development of the Web is at its peak.
In recent years, as the application of the Web becomes more and more extensive and in-depth, people gradually feel that HTML is not enough, and the overly simple syntax of HTML has seriously hindered the use of it to express complex forms. Although HTML has launched new versions after new versions and has already expressed functions such as scripts, tables, and frames, it has never been able to meet the growing demand. On the other hand, computer technology has also developed very rapidly in recent years, and it can already realize a much more complex web browser than when HTML was invented and created. Therefore, it is necessary and possible to develop a new Web page language.
Some people suggest using SGML directly as the web language, which can certainly solve the difficulties encountered in HTML. However, SGML is too huge, and it is not easy to learn and use users. It is very difficult to fully implement SGML browsers, so we naturally think that only a subset of SGML will make the new language both convenient to use and easy to implement. It is in this situation that the Web Standardization Organization W3C recommends a streamlined version of SGML - XML came into being.