If you want to be good apps trouble shooter, you should know how request
flow in apps across various components and which service or part of service
fulfill that request so that you can focus in particular component.
User makes a request from browser by typing URL like http://hostname:port ,
here port is WebServer Listen Port.
Request hit to WebServer (these requests are recorded in access_logs under Apache
Webserver checks that with http header request there is no cookie attached
(Cookie is message given by WebServer to Web Browser to identify client)
Webserver identifies that user is logging first time & it passes login page to
User . If Apps is configured to use 10G AS with SSO (Single Sign-On Server)
SSO authentication page is sent back to client browser.
User types his Username Password in login window & clicks submit button.
Webserver checks that username and passwords need to authenticate against
database FND_USER (or OID/AD incase of SSO configuration) table,
so it needs some user to connect to database. You know now why GUEST/ORACLE
is used in applications.
Once user is authenticated its check against FND_XXXX (FND tables)
for Authorization about users responsibilities & assigned responsibilities
are presented back to user.
Now these responsibilities are of two type Self Services(served by Jserv/Servlets)
or Core Applications served by Forms Server .
If this is Core responsibility , Apache transfers request to Forms Listener
and dedicated connection establish between client browser & form server
If User selected Self Service Responsibility like iProcurement, iRecruitement..,
Apache forwards request to mod_jserv and request is fullfilled by jserv_component.
Have you ever noticed why webserver donot ask client to login again until session
cookies , try deleting cookies from browser & see Oracle Apache asks you to
When your webserver tries to connect to database for plsql or any other
type of connection it asks mod_pls to fulfill request.
Users submits his requests for batch processing or somthing else
( Gather Stats done by Sysadmins or Apps DBA's) these kind of requests are
fullfilled by Concurrent Manager.
When user want to see reports of all these things request is being forwarded to Reports Server .
You as Sysadmin or Oracle Apps DBA need not to worry how this request
transmission happens from one service to another , this is transparent to you me or User
but its quite important to understand it as a process.