The document discusses the selection and use of Mule ESB as the integration platform. It describes how Mule was chosen over other open source ESBs based on criteria like maintenance, support, licensing, and performance. Intensive tests uncovered some issues with Mule 3.1.1 that were reported and addressed. Examples of how Mule was used include deploying it as a web application, integrating data sources, and building APIs. A custom lightweight Mule distribution was also created for optimal performance. The infrastructure migration involved a staged approach, integrating applications gradually over several phases.