文章基本信息

标题：Iterative process, 4GLs best for GUIs - Point/Counterpoint: graphical user interface: client server, host applications need different methodologies - Column
作者：Umang Gupta
期刊名称：Software Magazine
出版年度：1992
卷号：March 15, 1992
出版社：Rockport Custom Publishing, LLC

Iterative process, 4GLs best for GUIs - Point/Counterpoint: graphical user interface: client server, host applications need different methodologies - Column

Umang Gupta

Graphical client/server applications require a development methodology that differs from what is used to create traditional host applications. This is because there are some major differences between client/server and host-based dumb terminal applications.

By definition, graphical client/server applications are driven by graphical user interfaces (GUIs)--and graphical interfaces are fundamentally different from the character-based interfaces typical of host applications.

The best way to develop a GUI is through an interative process using a highly productive 4GL or graphical tool. During this process, programmers and analysts work with users through several cycles of refining the graphical interface. This differs from the paper-based specification process inherent to building a dubm-terminal application.

Most client/server applications are distinctly separated between front and back ends; for example, the front end consists of the user interface and the back end is the SQL database server. Thus, the programmer usually does not have to decide how to divide the application.

Eventually, the differences between front-end and back-end functionality will become less clear-cut. For example, certain parts of a cooperative processing application program might run on the front end while other parts, along with the database server, might run on the back end.

To maximize performance, data integrity and reliability, the programmer must determine where these parts belong. This might require development methodologies not yet available for mainframe-base monolithic applications.

One area in which client/server and host-based application development methodologies will probably differ very little is in the database design process. When using a SQL database, the question of whether that database is driven by a character-based dub terminal or a graphical PC does not affect the actual database structure. The methdology behind developing normalized table and column definitions and data dependencies is basically the same for both. Thus, the tools available for both are likely to be the same.