This Topic is quite important and I recommend you to go through this
First I want to discuss terminology which you will encounter in this site &
in most of Oracle Documentation.
Server - is a process or group of processes and provides a particular
functionality/service For example, Database Server listen and process database
requests, similarly Web Server listens for and processes HTTP requests.
Tier - is a logical grouping of services, may be on single machine
or spread across more than one physical machine. For Example, Middle Tier
in Oracle apps consist Form,Web,Report...Services. Forms & Report can be one machine 1
& Web Server can be on machine 2, still they will be part of same tier called as
Application Tier or Middle Tier.
Node - is referred as Machine, Each tier may consist of one or more node
and each node can potentially have more than one tier.
Oracle Applications/E-Business Suite is built on three tier Architecture with
first Desktop Tier ic client machines accessing applications via browser(HTML based
Self service applications) or Java Applet(Jinitiator) for Form based interface.
Second is Application Tier also called as middle tier consists of WebServer
Forms, Reports, Concurrent processing, Discoverer and Admin Server. I suppose its
known as Middle tier because it lies between our desktop & third tier called database tier.
Third is Database Tier contain Orale database server which store all your
Do you want to know how Request Flow in apps