Ask Slashdot: Which Java Applications Server?

MistaBobDobalina asks: I am looking at three open-source Java application servers for the purpose of building a database-driven website: Locomotive , Protomatter, and Enhydra. I am curious if anyone has experience with these or any other open source middleware solutions. I am also looking at commercial products but prefer an open product. I am making this query because three-tiered sites are now the norm for E-commerce and this is an area that the Open Source world hasn't addressed as well as operating systems, web servers, and databases have been."