WebSphere Commerce provides capabilities for cross-channel selling like catalog management and order management. It can integrate with external systems like inventory systems. WebSphere Message Broker is an enterprise service bus that simplifies integration between applications. It supports web services and message flows. To integrate WebSphere Commerce and Message Broker, you create transport and message types in Commerce, provide the Broker endpoint URL, and configure the Commerce database connection. In Message Broker, you create message flows to parse and extract Commerce messages, correlate requests and responses, and configure web service usage before deploying and testing the integration.