Here is the one stop place for all documentation for Oracle Application.  

http://www.oracle.com/technology/documentation/applications.html

It is well know fact the EBS Suit has includes many different APIs and integration technologies,such as PL/SQL procedures, Java classes, XML Gateway messages, Electronic Data Interchange (EDI) messages, open interfaces, concurrent programs, business events,and Web services.

Beginning with Oracle E-Business Suite 11i10, Oracle introduced a comprehensive online directory of Web services, interfaces, and integration points that act as the service broker for Oracle E-Business Suite. This directory functions as a catalog of all Oracle E-Business Suite integration points, including Web services, business-tobusiness (B2B) protocols, application programming interfaces (APIs), legacy integration technologies, and business events.

Then the next question is who can benifited if this would be the source of truth for all integration project, the answer would be it is open to:

•  Customers
•  Consultants
•  Integrators

And we can conclude this as powerful user interface for searching and viewing details all available Interfaces and other API'S.

The integration repository includes screens for searching and viewing all available integration points with just a Web browser.This is link which can be point to :http://irep11i10.oracle.com