Our custom applications are sending their log data to a SQL table. I am looking for a piece of software that will allow me to configure a rule engine to parse this data and look for certain patters that I will configure. For example I want to raise an alert when a certain event doesn't happen for more than x minutes, or a certain event doesn't succeed for more than y minutes, etc.
SnapOverflow
You can do this kind of things (and more) with Octopussy project. (disclaimer: it's my project)
You can also take a look at syslog.org website for other logging solutions.