app to DB servers over web

The application will be sending small pieces of data (about 2k) to a database via port 80 and I’m wondering the best way to go about setting up a redundant, scalable solution.

The network will be behind a Pix, but my concern is the application will be transmitting directly to the DB servers and some malicious coder could reprogram the .dll’s and do what he wants to our DB.

Does there need to be a web server in front of the DB servers?