What is cXML? Everything You Need To Know

Learn about the cXML data format, the role it plays with PunchOut catalogs, and how cXML PunchOut catalogs can help your B2B business to offer a superior eCommerce experience.

cXML, short for Commerce eXtensible Markup Language, is an XML-based protocol format that exchanges data between an eCommerce system, eProcurement system, and other business software to streamline B2B sales processes. The protocol defines how organizations transmit information and the steps involved in communicating documents and verifying that they have been received. The cXML format defines the structure and content of cXML documents via a set of XML Document Type Definitions (DTD).

cXML vs XML

XML is a widely used markup format, and XML DTDs define the rules that encode a specific type of document. If you’re familiar with HTML, you’ll recognize the format of XML documents, which use tags such as to enclose and describe the data. cXML DTDs cover most of the information that businesses want to exchange during procurement, as well as documents that support synchronization and integration throughout the B2B procurement process.

This protocol was first developed by Ariba in 1999 with input from numerous organizations. Ariba created it to provide an easy-to-use protocol for integrating eProcurement and eCommerce software, powering supplier catalogs, and automated procurement workflows.

Why the Format Matters in B2B eProcurement

While XML is a flexible markup language used across many industries, it was not designed to support the complex workflows required in B2B purchasing. cXML extends the XML framework with procurement-specific standards that streamline how buyers and suppliers connect, exchange data, and automate the order-to-cash lifecycle. 

Category	XML	cXML
Purpose	General data markup used across industries.	Built specifically for B2B eProcurement and eCommerce integrations.
Standardization	Varies by implementation; requires custom rules to align systems.	DTDs to support procurement workflows.
Document Types	Broad and not procurement-specific unless customized.	Includes standardized procurement documents such as PunchOut Setup Requests (POSR), PunchOut Order Messages (POOM), POs, PO Acknowledgements, Order Confirmations, Ship Notices, and Invoices.
Integration Complexity	Requires custom development for each buyer–supplier connection.	Designed for rapid, repeatable integrations between buyer eProcurement and supplier eCommerce systems.
Support for Automation	Limited without extensive customization.	Enables automated cart transfer, PO creation, order acknowledgement, and invoice exchange within TradeCentric workflows.
Real-Time Data Accuracy	Depends on individual system design; often static or delayed.	Ensures real-time catalog, pricing, and order data directly from the supplier’s eCommerce platform.
PunchOut Compatibility	Not inherently suited for PunchOut.	Native format for PunchOut catalogs and cart transfer workflows.

What is cXML format based on?

cXML format is based on the XML extensible markup language, which is used to store, transmit, and reconstruct data. These documents are composed of tag/value pairs that will be familiar to anyone who knows HTML. For example, the tag for encoding the name of an order’s recipient looks like this:

<first_name>Sally</first_name>
<last_name>Smith</last_name>
<unique_name>DKEf6d8</unique_name>
<user_email>[email protected]</user_email>
<user>DKEf6d8</user>
<business_unit>13843</business_unit>
<buyercookie 7555371f46f7a5d057ac3567a2df12c2</buyercookie>
<postform_url>https://acme_buyer.coupahost.com/punchout/checkout?id=1</postform_url>

cXML format describes a series of standard documents that eProcurement and eCommerce developers can implement.

In addition to the specifications, cXML documents also describe a pair of protocols for communicating data between platforms: a Request-Response model and a one-way model. The Request-Response model is used more widely and provides a protocol for two-way communication using standard HTTP(S) requests.

Check out our recent blog to see more practical cXML examples.

cXML vs. other document types

cXML vs X12 EDI

X12 EDI is an older protocol first developed in the late 1960s. It provides a set of standards for digitally exchanging information, but it is much broader in scope and although it supports the transfer of catalog data, it does not support eCommerce-integrated supplier catalogs. While cXML is tightly focused on procurement documents and supplier catalogs, EDI defines standards for communicating a huge variety of business documents.

cXML is less complex than EDI and less expensive to implement. XML is a widely supported markup language—most popular programming languages and frameworks support XML natively or via a library. Additionally, many eProcurement and ERP platforms support cXML out-of-the-box, which is not the case for EDI.

Because cXML is based on XML, it is extensible: organizations can adapt it to better meet their needs. EDI is much more complex and it is not designed to be extensible by the user.

Note: X12 EDI is a specific standard that supports EDI  (Electronic Data Interchange), and it is commonly referred to as “EDI” for short, even though other formats like cXML, JSON, and OCI can also be used for electronic document exchange.

Understanding the Right Protocol for Modern B2B Purchasing

Category	EDI	cXML
Scope of Use	Supports many document types across logistics, finance, supply chain, and more.	Focused on procurement documents such as PunchOut, POs, order confirmations, ship notices, and invoices.
Support for PunchOut & Integrated Catalogs	Does not support eCommerce-integrated PunchOut catalogs.	Native support for PunchOut catalogs and real-time cart transfer through TradeCentric.
Implementation Complexity	Complex, costly, and difficult to modify; requires specialized infrastructure.	Lower cost, simpler to implement, and supported natively in many eProcurement and ERP platforms.
Extensibility	Rigid format; not designed for easy customization.	Extensible XML structure allows organizations to adapt cXML to specific needs.
Technology Base	Uses proprietary EDI standards and requires dedicated translation systems.	Built on widely supported XML, compatible with most modern programming environments.
Real-Time eCommerce Interaction	Limited; primarily designed for batch processing.	Designed for real-time interactions between buyer systems and supplier eCommerce platforms.
Fit for Modern Procurement Automation	Suitable for standardized, predictable document exchange but not dynamic digital commerce.	Purpose-built for automated procurement workflows across the TradeCentric process.

cXML vs OCI

OCI (Open Catalog Interface) is SAP’s alternative to Ariba’s cXML. It is a standardized interface that can integrate a seller’s catalog into a buyer’s eProcurement or enterprise resource planning application, allowing buyers to build orders and have them transferred as a purchase order into their procurement platform.

In contrast, OCI is entirely focused on the PunchOut process, and it does not provide additional B2B procurement automation functionality such as invoice and advanced shipping order communication.

cXML vs OCI: Main Feature Differences

Category	OCI (Open Catalog Interface)	cXML
Primary Purpose	Provides catalog access and cart transfer from supplier to SAP procurement systems.	Supports end-to-end procurement workflows including PunchOut, POs, confirmations, ship notices, and invoices.
Scope of Integration	Focused exclusively on catalog and cart return functionality.	Broad, covering full procure-to-pay automation across the TradeCentric process.
Procurement Automation	Limited; does not support automated purchase orders, invoice exchange, shipping notices, or order acknowledgements.	Supports advanced procurement automation including invoices, acknowledgements, and ASNs.
Supported Document Types	Catalog call, cart return.	PunchOut Setup Request/Response, PO, PO Acknowledgement, Order Confirmation, Ship Notice, Invoice, and more.
Flexibility & Extensibility	Designed for SAP workflows; more rigid outside SAP environments.	XML-based and extensible, allowing customization to support specific supplier and buyer requirements.
Cross-Platform Compatibility	Best suited for SAP-centric procurement environments.	Works across a wide range of eProcurement, ERP, and supplier eCommerce systems.

How is cXML used in PunchOut catalogs?

For a PunchOut catalog experience to quickly and accurately transfer data back and forth, it uses commerce extensible markup language or commerce XML (cXML). Primarily used to exchange shopping cart data and electronic documents, such as purchase orders, ship notice documents, and invoices.

PunchOut catalogs allow a buyer to select a supplier from within their eProcurement solution. They are forwarded to the supplier’s eCommerce store and authenticated. Once they have selected the products they need, they transfer the order details to their eProcurement solution, where a requisition order is created.

In many eProcurement solutions and eCommerce applications, cXML is the data format that makes this level of integration and automation possible, streamlining the modern online procurement process and saving time and costs for the business.

What does integration using cXML look like?

Behind the scenes, a typical cXML PunchOut catalog integration looks like this:

• Buyer authentication: When the buyer selects a vendor, the eProcurement platform sends a PunchOut Setup Request to the seller’s eCommerce store. The request is accompanied by a cXML document that includes details such as the buyer’s name, contact information, and unique identifiers for authentication that vary by procurement system and by unique buyer requirements.
• Store or product page navigation: The eCommerce store responds with a PunchOut Setup Response, again accompanied by a cXML document that includes, among other data, the redirect URL of the store. The eProcurement platform redirects the user to that URL, which is generally the homepage or a page defined for the buyer organization. In the case of Level 2 PunchOut Catalogs, the user is sent directly to a product page.
• Order transfer: After products are selected, the buyer hits a “transfer order” button in the eCommerce store, which sends a PunchOut Order Message (POOM) to the eProcurement platform. The accompanying cXML encodes details such as product descriptions and ID numbers, unit prices, the unit of measure, UNSPSC codes and the currency. To some extent, these details can also vary by eProcurement solution.

From the buyer’s perspective, the  cXML PunchOut catalog integration process is entirely automated and intuitive. They choose a supplier, put items in their cart, and “check out.” The eProcurement platform and the eCommerce store invisibly handle authentication, data exchange, and requisition order creation within the buyers originating eProcurement or ERP system.

As fast and seamless as cXML data transfer process is, it can be further expanded with purchase order automation, which sends a purchase order to the supplier’s eCommerce store or order management system when an eProcurement requisition order is approved. Other documents include order confirmations, shipping notice documents and invoices.

Why use PunchOut and cXML?

PunchOut and cXML work together to create a faster, more accurate, and fully integrated B2B purchasing experience for both buyers and suppliers.  For companies that rely on eProcurement for business transactions, PunchOut creates a superior B2B eCommerce experience. cXML powers this connection by transmitting real-time catalog, pricing, and cart data between systems without manual effort.

Because cXML was purpose-built for procurement, it enables a level of accuracy, automation, and scalability that traditional manual processes or flat-file catalog uploads cannot support.

Benefits for buyers

• Eliminate error-prone manual data entry.
• Access approved suppliers in a single interface with a real-time product, availability, and pre-negotiated pricing.
• Improve procurement productivity and accelerate the purchase cycle.
• Centralize procurement data to increase visibility and control spending.

Benefits for suppliers

• Increase revenue by becoming easier for eProcurement users to integrate and purchase from.
• Deliver up-to-date, personalized catalogs without maintaining multiple static files.
• Reduce procurement costs by moving buyers to their eCommerce platform instead of more expensive, labor-intensive channels.
• Strengthen customer retention by offering a frictionless, system-to-system buying experience.

A recent study from Digital Commerce 360 revealed that eProcurement is the fastest growing B2B sales channel and that eProcurement users want to integrate as many suppliers as possible for PunchOut and other procurement automation functionality.

What are the benefits of PunchOut catalogs and cXML?

PunchOut catalogs and the cXML protocol deliver measurable benefits to both buyers and suppliers by streamlining how they connect, transact, and manage procurement processes.

For suppliers

Suppliers benefit by offering a seamless, scalable way to serve enterprise customers that require PunchOut support. With cXML, suppliers can automate catalog delivery and order intake, reducing reliance on manual channels such as phone or email. This increases order accuracy and shortens sales cycles. It also strengthens buyer relationships by ensuring a consistent, personalized shopping experience aligned with negotiated terms.

Together, PunchOut and cXML support a higher level of procurement automation. Additional cXML-based documents, like purchase orders, invoices, and shipping notices, extend integration beyond the cart, helping both parties reduce friction, cut costs, and grow revenue through digital efficiency.

For buyers

The cXML PunchOut catalog integration simplifies sourcing by allowing access to supplier catalogs directly within their eProcurement system. This eliminates the need for manual data entry and ensures users are always interacting with up-to-date products, pricing, and inventory. Buyers can build requisitions quickly, reduce errors, and accelerate approval cycles—all within their familiar procurement environment. Centralizing catalog data also improves spend visibility, compliance, and reporting.

TradeCentric protocol support

The TradeCentric Integration Platform supports cXML, EDI, OCI, and numerous other protocols and formats. We seamlessly translate between multiple formats, empowering B2B buyers and suppliers to integrate any eCommerce store with any eProcurement or ERP platform for supplier catalogs and purchase order automation. This ensures a streamlined process for both buyers and suppliers without the added expenses or complexities of inaccurate system mapping.