Oracle Applications Customizations is a major issue in many companies that have implemented it. Oracle recommends every company that installs Oracle Applications to avoid any customization, but I have not seen any company that utilizes it and have not done any customization.

There are two types of Customizations: Extensions and Modifications.

Extensions are components developed by customer, using the development features provided by Oracle within the E-business Suite. Oracle has provided guidelines and standards for creating extensions. It is extremely recommended that those are followed; it will certify that the new objects (extensions) are kept separate from standard E-business components.

Modifications are changes done in the standard E-business suite objects or code. For example, a customer gets a database trigger from Oracle Applications database and makes some changes in the code. When customers follow this approach it is very difficult to identify the changes that have been done in the Oracle Applications, and this will affect future upgrades.

There are some common extensions on Oracle Applications Suite:

Alert: Oracle Alerts facilitates the flow of information within a customers organization. Oracle workflow is used to develop new alerts.

Database Objects: when the functionality is not available in Oracle Applications, it is possible to create a set of database objects. If the creation is necessary, it has to be done carefully, once it could impact the performance and the integrity of the system.

File System and Custom Directory: always use the standard Oracle Flexible Architecture (OFA). This helps you to standardize installation and maintenance procedures. Create a new directory ($CUSTOM_TOP) and store all the customization in there.

Forms: provides a way of populating custom tables. Oracle has provided a guideline for its implementation that must be followed. It has to be coded and tested properly; otherwise it can compromise the data integrity.

Reports: Oracle provides the most usual reports and every company has to develop to their specific formats. Oracle Reports builder is the tool to be used and there are some risks in case of an upgrade, once that the schema of the objects used by Reports and Oracle eBusiness Suite can be changed in future releases.

Customization is a need at any company that has implemented Oracle Applications. Oracle is frequently advising everyone to avoid any kind customization. I agree in some part with Oracle, I would just change this advice to Extend but not modify.