Why would you want to execute a single rule?

The logic you'd write to determine which rule to fire should itself be part of the rules: So, for example, if you want to validate facts of type "Smurf" then write a rule that matches on "Smurf". When you insert a "Smurf" only the rules that match on this will become candidates for execution when you call fireAllRules. Perhaps use of a stateless session would simplify things so you need not worry about other facts in WM "polluting" the results you expect to see?

More and more questions are posted here asking how to make individual rules execute; IMO the solution is to change your thinking about how Rules Engines work.

If you give your use-case we might be able to advise a better approach.

With kind regards,

Mike