World Wide Web, a typical application of Internet
Source: Shangpin China |
Type: website encyclopedia |
Date: August 23, 2012
Beijing website construction Company Shangpin China: The rapid development of the Internet has enabled it to provide tens of thousands of services, most of which are free. The commercialization trend of the Internet will further increase the services it provides. This section mainly introduces the World Wide Web, e-mail, file transfer and BBS.
web
The World Wide Web is also called WWW, 3W or Web. The original purpose of designing it is to actively establish a "descriptive multimedia system". In fact, the World Wide Web is composed of numerous web pages. These pages are written in hypertext format, and users can easily jump from one page to another through these hypertext links. The development of the World Wide Web is very rapid, and the speed of its commercialization is amazing. Many companies have established websites on the World Wide Web to promote their products. Next, this book will briefly introduce the elements and working principles of the World Wide Web.
1. Components
The biggest success of the World Wide Web is that it has established a set of standard Hypertext Markup Language (HTML), Uniform Resource Locator (URL) and Hypertext Transfer Communication Protocol (HTTP).
(1) Hypertext Markup Language
HyperT ex t Mark up Language (HTML) is a text file containing various tags that can tell the browser which site to link to. The file written by HTM L language is called HTM L file, that is, hypertext file, and its extension is HTML or HTM。
(2) URL Address
The Uniform Resource Locator (URL) is a standardized naming method that provides a way to find the address of a www page. For users, URL is an address expression method of Internet information resources in a unified format. It addresses various services provided by the Internet in a unified way. When marking information resources in this way, you should not only indicate the directory and file name of the information file itself, but also indicate which host it exists on the network and how it can be accessed. Even if necessary, you should also indicate that it has more complex properties than ordinary file objects.
The format of the URL is: protocol://IP address or domain name/path/file name. Protocol refers to the method of obtaining data; IP address or domain name refers to the IP address or domain name of the host where the resource is stored; The path and file name are used to indicate the specific location of the host containing the resource. with //www.wuyou.com.cn/home.html For example, the protocol is http; The domain name is www.wuyou.com.cn, that is, the resources are stored on the host; Home.html is the file directory of the server.
(3) HTTP protocol
There is a large amount of information transmission in the network. To achieve correct transmission of such information, a "language" that both sides can understand is required. This language is "communication protocol". It is a standard that users must follow when using the network. Only information and data that follow this standard can be successfully transmitted on the network. HTTP (Hyper Text Transfer Protocol) protocol is the main protocol used by the World Wide Web services.
HTTP is responsible for hypertext data transmission between users and servers. HTTP is an application layer protocol in the TCP/IP protocol family, built on TCP. Its object-oriented features and rich operating functions can meet the requirements of distributed systems and various types of information processing. The HTTP session process includes four steps:
① The client using the browser connects to the server.
② The client submits a request to the server, indicating the specific file required in the request.
③ If the request is accepted, the server sends back a reply. The response shall at least include the status number and the contents of the document.
④ The client is disconnected from the server.
(4) WWW Browser
The client program of WWW is called WWW Browser, which is used to browse the Wel page in the World Wide Web. The WWW browser is connected to the www server using HTTP, and the Web page opened for browsing is made according to HTML. If WWW browser users want to browse the homepage content on the WWW server, they must first retrieve the homepage from the server according to HTTP, and then read the homepage according to the same HTML as when creating the homepage. Therefore, with the help of standard HTTP and HTML, any WWW browser can browse the WWW homepage stored in any WWW server, which provides users with great flexibility.
The wide application of WWW is due to the first WWW browser Mosaic. Since Mosaic, various browser software have emerged in endlessly. At present, the most popular browser software are Internet Explorer and Maxthon.
The www browser not only opens a convenient way for users to find rich and diverse home page information resources on the Internet, but also provides Internet newsgroups, e-mail, FTP and other means of communication. Moreover, today's www browser is very powerful, and it can access almost all information on the Internet. For example, users can directly access the e-mail server in the form of home page to browse their own e-mail. You can also query and process e-mail in a form that is very close to the e-mail interface. After the homepage producer inserts SQL statements into the www homepage, users can directly retrieve the data in the database through the www browser. The information entered by the user through the dynamic homepage can also be automatically transferred to the database for processing. In this way, the user can see the dynamic changes of the data in the database in real time without resorting to database professionals to obtain the required data through complex SQL queries, which greatly improves the efficiency and reduces the error rate.
With the development of www browser technology, www browser began to support some new features. For example, by supporting VRML (HTML format of virtual reality), users can see many dynamic home pages through the www browser, such as rotating 3D objects, and can control the movement of objects at will, thus greatly improving users' interest. The www browser supports the Java language. It can expand the functions of the WWW browser through a small application applet. Users can perform some tasks that cannot be supported before through A applet without installing an updated www browser. More importantly, the popular www browsers now basically support multimedia features. Sound, animation and video can be played through www browsers, making the WWW world more colorful.
2. Operating principle
The World Wide Web service adopts the client server working mode. Based on Hypertext Markup Language and Hypertext Transfer Protocol, it provides users with a unified interface information browsing system. These pages use hypertext to organize information, and link information from one page to another through links. These linked information can be placed on one host or on different hosts. The connection information of the page is maintained by the unified resource locator. The user sends a request to the www server through the client browser. The server returns a page to the client according to the request content. The browser interprets the page after receiving it, and finally displays the picture, text, and sound in front of the user. This article was published in UEO Marketing website construction Company Shangpin China //ihucc.com/
Source Statement: This article is original or edited by Shangpin China's editors. If it needs to be reproduced, please indicate that it is from Shangpin China. The above contents (including pictures and words) are from the Internet. If there is any infringement, please contact us in time (010-60259772).
