Oracle ERP World: Oracle APPS R12 Architecture

Sunday, February 17, 2013

Oracle APPS R12 Architecture – Technical Overview

R12 file system has come up with new model – Code, Data, Configurations are segregated nicely to have easy maintenance, to avert NFS mount issues on shared appl tier configuration systems. Auto-config will not write anything in APPL_TOP, COMMON_TOP area in R12. All instance specific configurations, log files are written in INST_TOP area. Instance Home provides the ability to share Applications and technology stack code among multiple instances.

Tech Stack Components

DB_TIER

10.2.0.2 RDBMS ORACLE_HOME

APPL-TIER

10.1.2 C ORACLE_HOME / FORMS ORACLE_HOME (8.0.6 ORACLE HOME equivalence)‏
10.1.3 Java ORACLE_HOME/OC4J ORACLE_HOME (iAS ORACLE_HOME equivalence)‏
INSTANCE_TOP : Each application tier has a unique Instance Home file system associated

Directory Structure

Below Image describes the complete directory structure for complete e-biz installation i.e. DB_TOP, APPL_TOP and new INST_TOP. If you dig into the INST_TOP you will find that it only contains all the configuration files, start-stop scripts, log files, certificate files, pid files etc.., so as to make DB_TOP and APPL_TOP untouched for any instance specific changes. So you can also make DB_TOP and APPL_TOP read only.

INSTANCE TOP
Instance home is the top-level directory for an Applications Instance which is known as Instance Home and is denoted the environment variable $INST_TOP. This contains all the config files, log files, SSL certificates etc.

Advantages of new INSTANCE HOME

The additional Instance Home makes the middle tier more easy to manage and organized since the data is kept separate from the config files.
The Instance Home also has the ability to share the Applications and Technology stack code across multiple instances.
Another advantage of the Instance Home is that the Autoconfig writes only in INST_TOP so APPL_TOP and ORACLE_HOME can also be made read only file system if required.
To create a new instance that shares an existing middle-tier, just create a new instance_top with proper config files and NFS Mount the middle tier

INSTANCE TOP – STRUCTURE

$INST_TOP      : $APPS_BASE/inst/apps/$CONTEXT_NAME/
/admin /scripts : ADMIN_SCRIPTS_HOME: Find all AD scripts here
/appl              : APPL_CONFIG_HOME. For standalone envs, this is set to $APPL_TOP
/fnd/12.0.0/secure : FND_SECURE: dbc files here
/admin             : All Env Config files here
/certs               : SSL Certificates go here
/logs                : LOG_HOME: Central log file location. All log files are placed here (except adconfig)
/ora                 : ORA_CONFIG_HOME
/10.1.2             : ‘C’ Oracle home config, Contains tnsnames and forms listener servlet config files
/10.1.3             : Apache & OC4J config home, Apache, OC4J and opmn
This is the ‘Java’ oracle home configuration for OPMN, Apache and OC4J
/pids                : Apache/Forms server PID files here
/portal              : Apache’s DocumentRoot folder