Technical Notes

Musicnot.wmf (1656 bytes)

Technical issues can be perplexing! In this section we attempt to explain technical matters that have special interest in the WISL community.

Client/Server

Client/Server is a computing environment that is designed to take advantage of the best of both worlds of personal computing and multi-user computing. Usually an application is initiated on the PC workstation and most of the user interface activity is executed on the PC. However the data base that is associated with the application(e.g. customer and order records) is usually stored on the server. Some subroutines or processes of the application are also stored and executed on the server. Requests from the client and results of processes or the results of data base lookups are passed back and forth between the two systems as "objects" over the network. Hence the user gets the familiar point and click interface and the data integrity of a true multi-user shared data system.

Components

	Client computer system(usually a PC workstation)
	Server computer system - running a multi-user operating system (e.g. UNIX, Windows NT, LINUX)
	A Network, hardware and software e.g. Ethernet & TCP/IP
	Middleware, usually object oriented software e.g. UniVerse Objects
	An application language that executes on the client and interfaces with the server via the middleware e.g. Visual Basic

Client Network Server

Computr2.wmf (17236 bytes) soundwav.wmf (3446 bytes) comp9.wmf (5462 bytes)

Example

In QUIKREP/CS the user is prompted for the name of the desired target file for reporting using a list box presented by the program running on the client. The contents of the list were earlier retrieved where they are stored on the server. The user enters various report specifications under control of the program running on the client but when the interactive activity is complete the file of specifications is passed to the server for the report to be executed. The results from running the report program are passed back to the client to be displayed under control of a process running on the client. In this manner the routine which is normally initiated on the client utilizes the strengths of each computing environment to provide the optimum operating solution for the user.