Description of the illustration multitierproxyarch.gif

This graphic has on the left the label "Clients" bounded by a dotted line. To its right is a box labeled "Firewall," and to its right is a column of two-sectioned boxes labeled "HTTP Server" and "Proxy Plug-in." This column of boxes is labeled "Web Servers (Web tier)." To the right of this column is a column of pentagons labeled "Servlet Cluster (presentation tier)." Each pentagon contains the labels "JSP" and "Servlet." To the right of this column is another column of pentagons labeled "Object Cluster (object tier.}" Each pentagon contains the label "EJB." Following this column is a database.

Clients points through the Firewall to each of the HTTP Servers. Each of the HTTP Servers points as a group with three arrows to each of the pentagons in the Servlet Cluster (presentation tier) and then each of the pentagons in the Object Cluster (object tier). Each of these pentagons then points to the database.