Open Catalog Interface 
Purpose
The Open Catalog Interface (OCI) is the interface between catalogs and Enterprise Buyer professional edition. SAP’s Open Catalog Interface uses standard Internet protocols. It has already been implemented between several catalog applications and Enterprise Buyer.
Integration
The graphic below shows how catalogs are integrated with Enterprise Buyer.

Structure
The catalog interface consists of two separate and distinct sections: the outbound section and the inbound section.
outbound section defines the information being sent from the Enterprise Buyer application to the catalog application. This includes information such as the catalog URL and login data.
The
inbound section consists of the information being sent from the catalog application to the Enterprise Buyer application. This section contains data on the items selected in the catalog, such as the items descriptions, quantities ordered, and prices. For more details, see the interface diagram under Inbound Section.