Client/Server Computing
Published by: Anil K. Panta
A model of computing in which powerful personal computers are connected in a network together with one or more servers
Client is a powerful personal computer that is part of a network; service requester
Server is a networked computer dedicated to common functions that the client computers on the network need; service provider
Web is based on client/server technology. Web servers are included as part of a larger package of internet and intranet related programs for serving e-mail, downloading requests for FTP files and building and publishing web pages. Typically the e-commerce customer is the client and the business is the server. In the client/ server model a single machine can be both client and the server The client/ server model utilizes a database server in which RDBMS user queries can be answered directly by the server.
client/ server architecture reduces network traffic by providing a query response to the user rather than transferring total files. The client/ server model improves multi-user updating through a graphical user interface (GUI) front end to the shared database. In client/ server architectures client and server typically communicate through statements made in structured query language (SQL).
Web Clients:
It typically refers to the Web browser in the user's machine. It is a software application for retrieving, presenting, and traversing information resources on the web server. It is used to create a HTTP request message and for processing the HTTP response message.
User agent: Any web client designed to directly support user access to web servers is known as user agent. Web browsers can run on desktop or laptop computers. Some of the browsers are: Internet Explorer, Mozilla, FireFox, Chrome, Safari, Opera, Netscape Navigator.
Web Browsers:
Browsers are software programs that allow you to search and view the many different kinds of information that's available on the World Wide Web. The information could be web sites, video or audio information.
Web Servers:
Basic functionality:
It receives HTTP request via TCP
It maps Host header to specific virtual host (one of many host names sharing an IP address)
It maps Request-URI to specific resource associated with the virtual host
File: Return file in HTTP response
Program: Run program and return output in HTTP response
It maps the type of resource to appropriate MIME type and use to set Content-Type header in HTTP response.
It Logs information about the request and response
All e-commerce site require basic Web server software to answer requests from customers like;
Apache
Leading Web server software (47% of market)
Works with UNIX, Linux , Windows OSs
Microsoft’s Internet Information Server (IIS)
Second major Web server software (25% of market)
Windows-based
