1. CSE350 Software Design and Engineering University of Pennsylvania http://www.cis.upenn.edu/~jms 254 Moore GRW, 8-9509 January 16 th, 2001

2. Administrative lTA, Chuck Davin, davin@dsl.cis.upenn.edu davin@dsl.cis.upenn.edu lMy Office Hours are T/Th 8:30 or by Appt. – jms@cis.upenn.edujms@cis.upenn.edu lNo mid-term or final; 100% of the grade based on term project implemented by a group of 3 people lPlagiarism results in an “F”

3. Course Organization lPrinciples and Practice lLearn by listening and doing lTuesday’s classes will be lectures on topics from the syllabus lThursday’s classes will be focused on material needed for the project lProject will be kernel coding for OpenBSD – implementation of IP striping

4. Syllabus lBulk Pack ready next week – copy center lOpenBSD CD-Roms when groups are formed lwww.openbsd.org to read aheadwww.openbsd.org lNeed to program in “C” lLarge vs. Small Systems – scale lSoftware lifecycle lSW reuse. Tools. lProgramming as a group activity lSW Testing lDocumentation lLegal issues

5. What is SW Engineering? lSW systems are large and complex lSociety increasingly relies on them lThey are enormously costly lThey are engineered artifacts lOpportunity: engineering discipline lSo far: not really there. But why???

6. It’s not like other engineering! lMathematics exists for the rest of engineering lAdd cement, power, pressure,… voila! lSoftware systems are “non-linear” lChanging a single bit may break the program lAre there any principles?

7. Most “principles” are empirical lAdding programmers slows things down lCost rises with complexity lComplexity is difficult to measure l10% of the cost is development l90% of the cost is maintenance lMajor cost factor is people lAt a certain scale, it’s a management problem

8. Complexity lAll metrics are approximate -Lines of code? -Number of branches? -McCabe’s complexity measure? #programmers Complexity increasing….

9. Perhaps the central question is: lIf you want to build a VERY complex system, are you better off Enhancing “super-programmer” Managing an “army of ants” What do you think????