From C / S to Intranet
(This article is reproduced from Software Engineering Expert Network www.21cmm.com)
First, c / s yesterday yesterday
After the arrival of the PC, computer networks and computer applications have been greatly developed. The continuous decline in PC prices and the continuous rise in performance will gradually drive large-scale hosts in the core-oriented network era to the corner of the network application. The rise of NetWare and Windows NT, as well as the dust in the large database system, opened up new modes of the network application - client / server (C / S) mode. This mode is a network system that occurs a distributed calculation process in the second phase of the computer network. Although from definitions, the C / S mode refers to any network system that separates transaction processing, but most of the C / S application systems are C / S database systems. A large database system, such as Sybase, Oracle, Informix, etc. The C / S mode is a two-layer structure: the first layer is a combination of representation and business logic on the client system; the second layer is combined with the database server through the network. In the past few years in Web and Intranet technology, C / S technology helped companies and companies in the world improved work efficiency. However, the C / S mode of the two-layer structure also exists in terms of integration and maintenance of the system, the operation interface consistency, the system's scalability, etc. These limitations are in today's network technology environment, which will make the C / S mode network system ultimately face the same destiny like host terminal network.
Second, the mainstream of Web and Intranet today
Web technology-based intranet is being widely concerned, which is based on TCP / IP protocol, and the internal network of Web-based enterprises is attracting more and more companies. Low-cost, easy-to-use customer browsers can access the data they need at any time, anytime, anywhere. The consistency of the client operation interface overcomes the inconsistency of the enterprise data from the two-layer structure C / S mode client, and the server-side open and standard connection plan, greatly strengthened the company and the external connection. At the same time, the dynamics, interactive information issued improved the quality of services to customers, increasing business opportunities. In the three-layer web technology, the database is not directly serving each client, but is communicated with the web server to realize the dynamic, real-time and interactivity of the customer information service. This feature is implemented by server applications created by CGI, ISAPI, NSAPI, and Java. Web technology attractive places to use hyperlinks and multimedia information. Web Server Use Hypertext Markup Language (HTML) to describe the resources of the network, create a web page, and save it in the form of an HTML data file for web browser. The HTML document is characterized by accounting. Hyperlink enables links in the text, whether it is general text or graphics, can connect to other documents on the server, so that customers quickly search for the information they want. The HTML web page can also include a form for users to fill in and submitted to the database via the server application. This database is typically supporting multimedia data types. The web browser is a client application for document retrieval and display, and is connected to the web server via Hypertext Transfer Protocol HTTP protocol. GM, or even free browsers eliminate the development and maintenance costs of the C / S mode client diverse software. Currently, popular Internet Explorer and NetScape Navigator provide basic document retrieval, display, and navigation features, but also supports HTML's advanced display (such as tables and frames), and features such as ActiveX, Java, JavaScript.
Third, the principle of web product selection
