Before going to far I would make myself familiar with what Sybase already offers. They offer monitor server, and historical server (which I believe saves monitor servers data), and if you can upgrade Sybase 12.5 has built-in monitoring tables called MDA tables.
The following site has info on the MDA tables and is a great general Sybase reference site too
I should also mention that I use a DataAccess class that does all my jdbc and I make calls in it to JAMon to monitor all my jdbc. One advantage of this approach is that it will monitor any database not just Sybase. This is viewable in an html report.