Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!dali.cs.montana.edu!uakari.primate.wisc.edu!sdd.hp.com!wuarchive!uunet!mcsun!ukc!edcastle!hwcs!styri From: styri@cs.hw.ac.uk (Yu No Hoo) Newsgroups: comp.software-eng Subject: Re: Provocative statement Message-ID: <2905@odin.cs.hw.ac.uk> Date: 7 May 91 11:06:26 GMT References: <1991May3.195844.25823@dg-rtp.dg.com> <34081@mimsy.umd.edu> Sender: news@cs.hw.ac.uk Organization: Computer Science, Heriot-Watt U., Scotland Lines: 26 In article <1991May3.195844.25823@dg-rtp.dg.com> cole@farmhand.rtp.dg.com (Bill Cole) writes: >>Jim Showalter writes: >> >If the bridge designer wants to have a greater security factor, >> >(s)he can specify a little thicker steel and cables than suggested >> >by standard calculations. The software designer cannot say: "This >> >system has to be really safe and secure, so let's put in 30% more >> >code!" >> >> I disagree strongly with this. It has been my experience that the >> systems that are engineered from the outset to have excellent error >> detection and correction mechanisms are quite robust and >> fault-tolerant. Often, the amount of error code that is involved CAN >> be about 30% of the total. I guess we're about to mix up "design" and "implementation" here. Robust code is usually a result of the design. The bridge design analogy of adding more lines of code (eg. of the error checking kind) would probably be to add more wires and beams (just in case...) based on "gut feeling" more or less. The resulting bridge may develop a failure due to excessive weight. ---------------------- Haakon Styri Dept. of Comp. Sci. ARPA: styri@cs.hw.ac.uk Heriot-Watt University X-400: C=gb;PRMD=uk.ac;O=hw;OU=cs;S=styri Edinburgh, Scotland