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CSE350 Software Design and Engineering

Explore the history of software development from UNIX origins to the impact of hackers and networked communities on open source culture. Delve into key topics like licensing, methodologies, and the shift from love to money in software creation.

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CSE350 Software Design and Engineering

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  1. CSE350 Software Design and Engineering University of Pennsylvania http://www.cis.upenn.edu/~jms Office: 254 Moore GRW, Phone: 8-9509 February 26th, 2002

  2. Administrative • Homework #2 due next Tuesday • How are people doing with it? • Many readings handed out today • If not enough, see Cheryl Hickey in Moore 269 • Basic topics: open source, licensing, software development methods • Note Microsoft methodology

  3. Next few (Tuesday) classes • Software Development: Love or Money? • We’ll look at Open Source history • Excerpts from: • GNU Documentation (Manifesto/Glossary) • Raymond’s “Cathedral and Bazaar” (History/CAB) • Cusumano/Selby “How Microsoft Builds Software” • all except the last (of course!) readily available on the net!

  4. Hackers • I differentiate hackers from crackers • Hackers are curious programmers, who play with systems to learn more • Crackers are hackers who discover and exploit system security errors • Analogues from other fields: • Automobile hobbyists (“gearheads”) • Woodworking hobbyists (“knotheads”?) • People who work on software for (exaggerating a bit, but only a bit…) love, not money

  5. UNIX • Technical issues: see January 10th slides • UNIX came from an earlier academic / research operating system: MULTICS • UNIX initially Bell Labs internal, paid for by legal department for word processing tasks (if I remember correctly) • “Licensed” for $300 – for magtape containing system – to universities • Source code + simple and easy to teach • Many books (e.g., Lions) to teach with…

  6. UNIX + Hackers • Source code allows deep understanding • Read good code -> write good code • It allows tinkering • C “high-level” enough for comprehension, “low-level” enough for manipulating anything • Preferred environment for sophisticated programmers

  7. Unix + Hackers + Networks • uucp – Unix to Unix copy • Used to architect the “USENET” / netnews: on-line communities • Addresses: upenn!cis!central!jms (this is called “source routing”) • BSD Unix funded by DARPA for “image processing”(!); ARPAnet connectivity available to ARPA funded Univs.

  8. Common code base + sharing • Available source code meant that modifications could be shared – just recompile • Subset of on-line community: hackers • Networked hackers share source code • Examples: • xgetment (in use for 10 years!) • lucifer (in Schneier book)

  9. Profit to the rescue? • AT&T began “commercializing” UNIX • Enforcing licensing / charging a lot / decomposing system into salable elements (e.g., compiler subsystem) • This caused a “political fork” with networked hackers – who were used to cooperative underground • Issues with U. Cal / Berkeley Distribution • Berkeley identifies AT&T-derived code (example of “intellectual property” in action…)

  10. Reactions from “networked hackers” • Outrage from segments, e.g., RMS • GNU Manifesto • “Free Software” • As in “free speech”, not “free beer”  • BSD project terminates, releases “BSD-lite” (no AT&T code, thanks) • High-quality free code: • gcc (no longer viable to write compilers for $$) • GNU emacs

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