What is cXML? The Complete Guide to Commerce XML

Need to understand cXML for B2B procurement? You’re in the right place. cXML (Commerce eXtensible Markup Language) is the standard protocol that enables automated purchasing between businesses—from PunchOut catalogs to purchase orders to invoices.

This guide covers everything you need to know: what cXML is, how it differs from XML and EDI, the cXML format and structure, and how PunchOut catalogs work.

cXML at a Glance

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What is cXML?

cXML (Commerce eXtensible Markup Language) is a standardized protocol for communicating business documents between procurement applications and suppliers over the internet. Created by Ariba in 1999, cXML defines how purchase orders, invoices, shipping notices, and catalog data should be formatted and exchanged.

In plain terms: cXML is a common language that lets procurement software “talk” to supplier systems automatically—no manual data entry, no phone calls, no PDFs.

What cXML handles:

• PunchOut catalog sessions (browsing supplier catalogs from within your procurement system)
• Purchase orders and order confirmations
• Invoices and payment requests
• Shipping notifications
• Catalog content updates

cXML is an open standard—the specification is publicly available, and any company can implement it without licensing fees.

cXML vs XML: What’s the Difference?

This is a common source of confusion. Here’s the simple explanation:

XML (eXtensible Markup Language) is a general-purpose markup language for structuring data. It’s like a blank template—you can use XML to describe anything (recipes, books, weather data, etc.).

cXML (Commerce XML) is a specific application of XML designed for B2B procurement. It defines exactly what tags to use, what data goes where, and how systems should interpret the information.

Think of it this way: XML is like the English language—you can write anything. cXML is like a standardized purchase order form—everyone knows exactly where to put the quantity, price, and shipping address.

cXML vs EDI: Key Differences

Both cXML and EDI (Electronic Data Interchange) automate B2B document exchange. But they evolved in different eras for different needs.

When to Use cXML

• Your buyers use procurement platforms (Ariba, Coupa, Jaggaer)
• You need PunchOut catalog functionality
• You want real-time order communication
• You’re integrating with modern eProcurement systems

When to Use EDI

• Trading partners require it (Walmart, Amazon Vendor, healthcare)
• You process high volumes of standardized documents
• Partners use traditional supply chain systems
• Compliance requires specific EDI standards (X12, EDIFACT)

Can cXML and EDI Work Together?

Yes—many businesses use both. cXML handles procurement platform integrations while EDI manages traditional supply chain partners. Integration platforms like Comparatio can translate between formats, so you work in one system regardless of what your partners use.

cXML Format and Structure

cXML documents follow a consistent structure. Understanding this format helps when troubleshooting integrations or working with developers.

Basic cXML Structure

Every cXML document has three main parts:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE cXML SYSTEM "http://xml.cxml.org/schemas/cXML/1.2.050/cXML.dtd">
<cXML version="1.2.050" timestamp="2026-01-28T10:30:00-05:00">
  <Header>
    <!-- Authentication and routing info -->
  </Header>
  <Request>
    <!-- Or Response, or Message -->
    <!-- The actual business document -->
  </Request>
</cXML>

The Header Section

The Header identifies who’s sending and receiving the document:

<Header>
  <From>
    <Credential domain="NetworkID">
      <Identity>BuyerCompany</Identity>
    </Credential>
  </From>
  <To>
    <Credential domain="NetworkID">
      <Identity>SupplierCompany</Identity>
    </Credential>
  </To>
  <Sender>
    <Credential domain="NetworkID">
      <Identity>BuyerCompany</Identity>
      <SharedSecret>password123</SharedSecret>
    </Credential>
    <UserAgent>Procurement System 1.0</UserAgent>
  </Sender>
</Header>

Common cXML Document Types

• PunchOutSetupRequest – Initiates a PunchOut session
• PunchOutSetupResponse – Returns the catalog URL
• PunchOutOrderMessage – Shopping cart contents
• OrderRequest – Purchase order
• ConfirmationRequest – Order acknowledgment
• InvoiceDetailRequest – Invoice submission
• ShipNoticeRequest – Shipping notification

What is cXML PunchOut?

PunchOut is one of the most common uses of cXML. It allows buyers to browse a supplier’s online catalog from within their procurement system, then bring selected items back for approval and purchase.

How PunchOut Works (5 Steps)

1. Initiation – Buyer clicks on a supplier in their procurement system. The system sends a PunchOutSetupRequest to the supplier.
2. Authentication – Supplier validates the buyer’s credentials and returns a PunchOutSetupResponse with a URL to their catalog.
3. Shopping – Buyer is redirected to the supplier’s website. They browse products, configure options, and add items to their cart. The buyer’s session is maintained throughout.
4. Cart Transfer – When done shopping, the buyer clicks “Submit” or “Return to Procurement.” The supplier sends a PunchOutOrderMessage containing the cart contents back to the procurement system.
5. Order Processing – The procurement system receives the cart, applies approval workflows, and (when approved) sends a formal OrderRequest to the supplier.

PunchOut Benefits

• Real-time pricing – Buyers see current prices and availability
• Contract compliance – Only approved suppliers appear in the system
• Reduced errors – No manual re-keying of order data
• Streamlined approvals – Orders route through standard workflows
• Catalog management – Suppliers maintain their own product data

cXML vs OCI for PunchOut

Two standards exist for PunchOut: cXML and OCI (Open Catalog Interface).

Most modern procurement platforms support both. If you’re implementing PunchOut, check which format your buyers’ systems prefer.

Implementing cXML

Prerequisites

Before implementing cXML, you’ll need:

• Technical resources – Developers familiar with XML and web services
• Trading partner credentials – Network IDs and shared secrets from your buyers
• HTTPS endpoint – A secure URL to receive cXML documents
• cXML schema knowledge – Understanding of the document types you’ll exchange

Common Implementation Challenges

Schema validation errors – cXML documents must conform to the DTD. Missing required fields or incorrect formatting will cause rejections.

Credential mismatches – The From/To/Sender credentials must match what the trading partner expects. Mismatches are the #1 cause of failed connections.

Character encoding – cXML requires UTF-8 encoding. Special characters in product descriptions can cause parsing failures.

Timeout issues – PunchOut sessions have time limits. If buyers take too long, sessions expire and carts are lost.

How Comparatio Simplifies cXML Integration

Implementing cXML from scratch requires significant development effort. Comparatio’s integration platform handles the complexity:

• Pre-built connectors – Connect to major procurement platforms without custom development
• Format translation – Automatically convert between cXML, EDI, and API formats
• PunchOut hosting – We handle the technical infrastructure for PunchOut catalogs
• Error handling – Automatic validation, retry logic, and alerting
• Single dashboard – Monitor all your B2B transactions in one place

Whether your trading partners use cXML, EDI, or APIs, Comparatio translates so your team works in one system.

See how Comparatio simplifies B2B integration →

Summary

cXML is the standard protocol for B2B procurement communication—enabling PunchOut catalogs, automated purchase orders, and seamless integration with eProcurement platforms.

Key takeaways:

• cXML is XML specifically designed for commerce (not general-purpose)
• It differs from EDI in format, transport, and use cases—but both have their place
• PunchOut catalogs are cXML’s most common application
• Implementation requires understanding the cXML format and your trading partners’ requirements

If your buyers use procurement platforms, cXML capability isn’t optional—it’s how business gets done.

Frequently Asked Questions

What does cXML stand for?

cXML stands for Commerce eXtensible Markup Language. It’s an XML-based standard for B2B procurement communication, created by Ariba in 1999.

What is cXML used for?

cXML is primarily used for electronic procurement—exchanging purchase orders, invoices, shipping notices, and catalog data between buyers and suppliers. Its most common application is PunchOut catalogs, where buyers browse supplier websites from within their procurement system.

What is the difference between cXML and XML?

XML is a general-purpose markup language for structuring any type of data. cXML is a specific implementation of XML designed for B2B commerce—it defines exactly which tags to use and what data to include for procurement documents.

What is the difference between cXML and EDI?

cXML is an internet-age standard (1999) using human-readable XML over HTTPS, designed for real-time procurement. EDI is a pre-internet standard (1970s) using fixed-position formats, typically for high-volume batch processing in supply chains. Many businesses use both depending on their trading partners.

What is a cXML PunchOut catalog?

PunchOut is a protocol that lets buyers browse a supplier’s online catalog from within their procurement system. The buyer “punches out” to the supplier’s website, shops for items, and brings the cart back to their procurement system for approval. cXML handles the communication between systems.

Is cXML still used?

Yes—cXML remains the dominant standard for eProcurement integration. Major platforms like SAP Ariba, Coupa, and Jaggaer all use cXML for supplier connectivity. If you sell to enterprise buyers, cXML capability is often required.

How do I implement cXML?

You can build cXML integration in-house (requires development resources and XML expertise) or use an integration platform like Comparatio that provides pre-built connectors and handles the technical complexity.