The standard model of communication over the World Wide Web and the Internet, which carries it, is called the client-server model. In this, the application that displays Web pages is called the client software. This is the Web browser. The application that stores and distributes webpages is called the Web server, which is the “server” part of “client-server.” The advent of databases resident on separate servers introduced another element to the client-server architecture, creating three-tier Web-based information systems.
Web-based information systems developed out of two technologies. The first is office-based information systems, like Enterprise Resource Planning systems. The second was the development of Web-based communication over the Internet. A Web-based information system applies the data representation and transport methods to standard information systems.
Traditional information systems use the client-server architecture also. The client computer accesses an interface system to a database, which is held on a central server. The client software in this case is a terminal emulator program that presents a view of the database interface screens. These screens are also known as forms. Most database applications use a proprietary interface application developed by a database provider, like Oracle Forms, or a productivity application, like Microsoft Excel. Often the presentation of the data is customized for each company. The switch to using Web-based methods is standardizing the delivery methods for commercial information systems.
The two key elements of the delivery of Web-based information systems are the Hypertext Markup Language and the Hypertext Transfer Protocol. These two systems, better known as HTML and HTTP are the basis of world wide web communication. HTML is the formatting language used to create Web pages and HTTP is the protocol used to request and deliver webpages. A Web-based information system does not have to cross the Internet. Web delivery methods can also operate on private networks. In these cases the network is called an “Intranet.”
The three major components of a Web-based information system are the Web browser, the Web server and the database. The Web browser interprets the front-end presentation of data, the Web server stores those screens in files and the database stores the data that populates information screens. The three elements do not always equate to three different computers because the Web server and the database server can be resident on the same computer. It is their operating software that divides them as two separate systems.
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