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X ( [#!IB-H915012!#], [#!IB-B911403!#], [#!IB-H925537!#] ) is a windowing system built for UNIX but is intended to be machine and operating system independent. X is built on the client/server model. The server side of X resides on the desktop computer and controls the monitor, keyboard, and mouse. The client side of X may reside anywhere on the network. These X clients are called X-applications. A protocol, the X protocol, is used to communicate between X client and X servers.

X is a windowing system and not a user interface paradigm. Motif is the most common accepted user interface paradigm specifying sliders, buttons, basic design of windows, and other widgets.

X was created in the 1980s at MIT. The team was very small lead by Jim Gettys. X is well documented and the source code is free and readily available.

There were two decisions which hampered the wide acceptance of X. The first decision was not to dictate a common look-and-feel. This lead to many different windowing paradigms. Many times competition leads to better answers, but in this case, competition lead to conflicts and interoperability between systems. Eventually, the standards committee for X picked Motif.

The second decision was to break the inode paradigm of UNIX. This meant that X could not be scripted. One application could no longer run another application in a piped manor. Attempts to fix this problem are underway in the TCL scripting language.

See tables 7.17 and 7.18 starting on page [*].

Table 7.17: Survey Part 1: Basic Properties X
Question Response
Analysis? none..poor..fair.. good..great
Design? none..poor..fair.. good..great
Implementation? none..poor..fair.. good..great
Testing? none..poor..fair.. good..great
Cycles of ADIT? one..few.. several..frequent
Priority? no.. yes
Versions? no.. yes
Change Order Control? no..yes
Internal Prototype? no.. yes
External Prototype? no.. yes
Alpha Release? no.. yes
Beta Release? no.. yes
Duration? 15 years
Effort? 100 person years

Table 7.18: Survey Part 2: Change Control X
Question Response
Did a new introduced requirement ever negatively affect accomplished work? never.. seldom..often..frequent
Did an architectural change ever negatively affect accomplished work? never.. seldom..often..frequent
Are new features introduced up to product release? never.. seldom..often..frequent
Is there a dedicated period of quality assurance before the product is released? no.. yes

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Next: Ada Up: Projects Previous: UNIX
Ronald LeRoi Burback