Oracle Applications File System

Oracle Applications file system architecture provides us information of the way the files are organized in in Oracle Apps. The Oracle applications system consists of a number of different types of files which constitute the whole system. We have pl/sql files,.fmb files for forms,.rdf files for Reports ,.pll library files , java ,html files and other files. The file system Architecture is concerned with the orderly organization of these in the system.

An Oracle Applications system utilizes components from many Oracle products.These product  files are stored below a number of key top-level directories on the database and application server machines
Database Server:
The DATA_TOP directory contains the table spaces, redo log files, data table spaces, index table spaces and database files.The DB  directory is located on the database server and contains Oracle HOME for the Oracle Database
Application Server:
The APPL_TOP directory contains the product directories and files for Oracle Applications.
The ORA directory contains the ORACLE_HOMEs for the Applications technology stack components.
The  COMN_TOP directory contains directories and files used across products.

COMMON_TOP: The COMMON_TOP directory contains files used by many Oracle Applications products.
The admin directory, under the COMMON_TOP directory, is the default location for the concurrent manager log and output directories. When the concurrent managers run Oracle Applications reports, they write the log files and temporary files to the log subdirectory of the admin directory, and the output files to the out subdirectory of the admin directory.

APPL_TOP: The APPL or APPL_TOP directory contains the product directories and files for Oracle Applications.

Appl_Top Directory Structure

Each product has its own subdirectory under APPL_TOP. The subdirectories are named in accordance with the product’s standard abbreviation, such as gl for Oracle General Ledger.
Within each product directory is a subdirectory that is named using the base Applications release number, such as 11.5.0.
Product Files :
Each <PROD>_TOP directory, such as <APPL_TOP>/gl/11.5.0, contains subdirectories for product files. Product files include forms files, reports files, and files used to upgrade the database. To display data entry forms for Oracle General Ledger, for example, Oracle Applications accesses files in the forms subdirectory under the 11.5.0 directory.

Each <PROD>_TOP directory contains different types of files to be used by the <PROD>_TOP application to perform the actions and provide the functionality it is intended to, each of these directories has a number of sub directories created to organize the different files.

Given below are the folders created in each <PROD>_TOP to store the different files

Admin	Contains files used by Autoupgrade to upgrade each separate product
Bin	Contains concurrent programs, control files, shell scripts
Forms	Contains the fmb and fmx files
Help	Contains online help files which are imported suring installation
Html	Contains html,javascript and jsp pages eg : istore
Include	Include C lib header(.h) files
Java	Contains .class java files and .jar files
Lib	Contains lib files to link concurrent program to oracle database server
Log and out	Contains output files of concurrent programs
Media	Contains the graphic files
mesg	It contains .msb files. The messages displayed at the bottom of the screen and in the pop up boxes of Forms are stored here.
patch	Updates to the data or data model use this directory to store the patch files.
Reports	Contains the rdf files
Resource	Contails the pl/sql and .pll files of oracle forms
plsql	Contains PL/SQL library files (.pll) for Oracle Reports
sql	Contains SQL*Plus script files (.sql) for concurrent processing.

 The file system basically specifies which files need to be stored where because the oracle  system is designed to read specific files from the specified locations, for example the system will expect that if a form is created the .fmx file for the form will be found in the forms folder. 

A basic understanding of the file system is essential for the developers as it provides then knowledge of where to store which files in the system thus enabling smooth development of the system.