In order to modify or extend the sniffle system without vandalizing it, one must have a firm background in software systems and a good working understanding of a number of important issues. Minimal formal ``prerequisites'' include COS 217 and COS 228; COS 333 and COS 461 would be nice, as would experience with complex software projects involving thousands of lines of code. Before embarking on any modifications to snifflebecome familiar with all relevant components of the system (e.g. HTML, HTTP, cgi interfaces, the WinHTTPD server, serial communications, the Tektronix digital oscilloscope, I/O boards, etc.). A good way to learn about these issues is to complete a ``warm-up'' exercise; see the next section for ideas.
Most importantly, an orderly and methodical approach to development is essential. It is possible to hack together a small system (on the order of hundreds of lines of code) without writing clean, modular, well-documented, versioned code, but the ``quick and dirty'' approach does not scale well as project size and complexity increase and as re-usability and maintainability become important project goals. The point of the sniffle project is not to produce a one-time throw-away Rube Goldberg apparatus which merely accomplishes some special task. Rather, the point is to develop a robust, extensible, general-purpose tool whose usefulness transcends any particular task to which it is applied.
A project of this size requires disciplined software habits, foremost of which is version control. I have installed a DOS version of GNU RCS on our current server PC and have used it with the sniffle source code. At least two commercial version control utilites for Visual Basic are available, as are several documentation aids. These might well be worth the price. Select and learn a version control scheme before modifying any source code. Making regular (i.e. daily) backups is another essential habit. CIT's ADSM backup system might provide a long-term solution to the latter issue. Contact a company called ``VBxtras'' at (800) 788-4794 or (404) 952-6356 for more information on version control utilities for Visual Basic.