App Architecture

[Saman Perera]

Daer all
pls any one tell me why some applications use following application architecture for Web(JSP Servlet) + EJB Application

what is the concept and its prons and cons ,how it implemant


U-> Apache Web Server <--->Apache Tomcat <----> Jboss App Ser <---> DB ser


or some web app(JSP Servlet) use this , what is the concept and its prons and cons ,how it implemant


U-> Apache Web Server <--->Apache Tomcat <---> DB ser


Thanks All
Saman

[Christophe Verré]

Please do not crosspost
http://www.coderanch.com/t/318201/EJB-JEE/java/App-Architecture

Thank you