What is XML and what can it do? -- To the XML Publisher from sank orange)

What is XML and what can it do? -- To the XML Publisher

Http://blog.csdn.net/cds27/archive/2006/05/18/743409.aspx

XML to extend the markup language (Extensible Markup Language ). A tag is an information symbol that a computer can understand. Through this tag, a computer can process articles containing various information. To define these tags, you can either select an international markup language, such as HTML, or use a markup language that is freely determined by people like XML. This is the scalability of the language. XML is simplified and modified from SGML. It mainly uses XML, XSL, and XPath.

The above section is a basic definition of XML, a widely accepted description. Simply put, XML is a data description language. Although it is a language, it generally does not have the basic functions of common languages-it is recognized and run by computers. It can only be interpreted in another language to achieve the desired effect or be accepted by the computer.

If you are new to XML, you may not be able to understand what XML is. Maybe, you can understand what XML is from another angle; understand XML from the application side, and know what XML can do to understand it, which should be more helpful to you than the more empty definition.

XML applications are mainly divided into two types: document and data. The following describes several common XML applications:

1. Custom XML + XSLT => HTML, one of the most common document applications. XML stores the XML data of the entire document, and XSLT converts and parses the XML, combines the HTML tags in XSLT, and finally becomes HTML, which is displayed on the browser. A typical example is the post on csdn.

2. XML, as a micro-database, is one of the most common data-type applications. We use the relevant XML APIs (MSXML Dom, Java Dom, etc.) to access and query XML. The implementation of the message board often shows that XML is used as the database. At the same time, we want to tell new people that the two concepts of databases and database systems are different. The impact of XML on the database system is introduced here. In the new version of traditional database systems, XML has become a data type. Compared with "traditional", it is a new form of database, a database system fully based on XML-related technologies. Currently, exist is a well-known exist.

3. As the carrier of information transmission. Why is it a carrier? Although these applications are still in XML format, they have developed a specific format. The most typical is the Web service, which encapsulates data into XML for transmission, but the XML here already has a specific specification, that is, soap. However, I still have to mention Ajax. In Ajax applications, I believe that some applications use custom XML as data, but they are not the industrial standard. I will not elaborate on them here.

4. Application configuration data. The most typical is the Web. xml used when the J2EE Web server is configured. This application is easy to understand. We only need to store the required data into XML, and then load the program running in our application, and perform corresponding operations based on different data. This is actually a bit similar to Application 2. The difference is that the data changes in the database are normal, and the configuration information is often relatively static and lacks changes.

5. XML format of other documents. Such as Word and Excel.

6. Save the ing between data. Such as hibernate.

In these common applications, we can also divide them into custom XML and specific XML based on their wide application scope. 1 and 2 are the categories of custom XML; 3 to 6 are specific XML, or XML extensions.

The six applications described here basically cover the main usage of XML. In short, XML is an abstract language, which is not as specific as traditional programming languages. To understand it in depth, you should first start with its application, select a purpose you need, and then learn how to use it.

If any reprint is available, please indicate the source. Thank you.

Author: sank orange