OCI PunchOut (Open Catalog Interface)

⚠️ Source Note: Extracted from TradeCentric vendor blog. Protocol definitions reflect SAP/industry specifications. Do not attribute to Justin King or B2BEA.

OCI (Open Catalog Interface) is SAP’s proprietary protocol for connecting supplier catalogs to SAP procurement systems (originally SAP SRM — Supplier Relationship Management, now SAP Ariba and SAP S/4HANA). It is the SAP-world equivalent of cXML, enabling the same PunchOut workflow — a buyer accesses a supplier’s eCommerce site from within their SAP procurement system, builds a cart, and transfers it back as a requisition.

OCI PunchOut is also commonly called “OCI Round-Trip.”

How OCI Works

The OCI process mirrors PunchOut in its overall flow, but differs in the technical format:

Step 1 — Authentication Request
The SAP procurement system sends an OCI request to the supplier’s eCommerce site. Unlike cXML, OCI often transmits minimal user identity data — the primary piece of information is the HOOK_URL, which is the endpoint the supplier will POST cart data back to.

Example: HOOK_URL: https://acme_buyer.sap.com/oci

Step 2 — Buyer Redirection
After authenticating, the supplier’s eCommerce platform redirects the buyer to the shopping experience.

Step 3 — Cart Return
When the buyer transfers their cart, the supplier’s system posts line-item data directly to the HOOK_URL. Each line item includes parameters like:

• NEW_ITEM-DESCRIPTION[n] — product name
• NEW_ITEM-MATGROUP[n] — UNSPSC commodity code
• NEW_ITEM-VENDORMAT[n] — supplier’s product SKU
• NEW_ITEM-QUANTITY[n] — quantity ordered
• NEW_ITEM-PRICE[n] — unit price
• NEW_ITEM-UNIT[n] — unit of measure (EA, CS, etc.)
• NEW_ITEM-CURRENCY[n] — currency code

OCI supports up to 40 different parameters; most implementations use 7–15.

OCI vs. cXML

OCI

cXML

Origin

SAP proprietary

Ariba / industry standard

Primary use case

SAP procurement environments

All major eProcurement platforms

Scope

PunchOut (catalog call + cart return) only

Full procurement lifecycle: PunchOut + PO + invoice + ASN

PO / Invoice automation

Not supported via OCI

Supported natively

Cross-platform compatibility

Best suited for SAP environments

Works across Ariba, Coupa, Jaggaer, Oracle, and more

Extensibility

More rigid outside SAP

XML-based; extensible and adaptable

The critical limitation of OCI: it only covers the PunchOut session (catalog browsing and cart transfer). It does not support the subsequent automation of purchase orders, order confirmations, shipping notices, or invoices. Suppliers serving SAP-centric buyers who want full order-to-cash automation typically need both OCI and EDI, or they implement cXML alongside OCI.

When Suppliers Need OCI

Any supplier selling to an enterprise customer running SAP SRM, SAP Ariba (in OCI mode), or SAP S/4HANA procurement may be required to support OCI. The buyer’s IT/procurement team will specify which protocol their system uses.

Key signals that a buyer requires OCI:

• They are running SAP SRM or older SAP procurement
• Their eProcurement connection specification mentions “OCI” or “Open Catalog Interface”
• The HOOK_URL format is a SAP domain endpoint

Many large manufacturers and distributors encounter OCI requirements when selling to large industrial, automotive, or public sector accounts running SAP.