Electronic Voting Machine Use Case

(Strange, I thought I published this. I guess I must of hit the 'Save as Draft' button instead. Oh well. Better late than never I guess - 2006/12/04)

Electronic voting machines problems have been all over the news. I don't understand why there are so many problems. Is it that hard to program an electronic voting machine?

A basic Use Case would look something like this:

Use Case Name: Entering vote
Use Case Id: U1001
Actors: Voter, System, printer
Description: Voter selects candidate and is recorded.
Precondition: Voter logs into system
Postcondition: Vote is recorded.
Flow of Events:
- Voters selects the candidate they want to vote for.
- System asks to confirm.
- Voter confirms selection.
- System records the vote to memory card.
- System prints to printer.
- System returns a status message back to the user to show that their vote was recorded or there was an internal error.

Error Conditions:
- Voter selected incorrect candidate, return to selection screen Goto U1001
- System can't write to memory card. Goto E1001.
- System can't print to printer. Goto E1002.


Pretty straight forward Use Case.

So why are voting machine manufacturing companies having so many problems?

Here is a perfect example of things going wrong.

Zero Vote Tally Off - by 1