Description of the illustration recommendmultitierarch.gif
This graphic has on the left the label "Untrusted Clients" bounded by a dotted line. It is connected to "Firewall" with a line, which is further connected to "Load Balancer". The Load Balancer points to three boxes in "WebLogic Server Cluster(web, presentation tiers)".
Each box contains labels "HTTP", "JSP", and "Servlet". These boxes point as a group with three arrows to another column of boxes, labeled "WebLogic Server Cluster (object tier)". These boxes contain the labels "EJB" and "JDBC". All of these boxes points to a Database.