Transaction processing is a vital part of most real-world J2EE application development. In this article, IBM Solution Architect Mikhail Genkin explains how different enterprise information systems (EIS) can participate in transactions via the J2EE Connector Architecture. Using an example e-commerce application, Mikhail demonstrates the various levels of transaction support provided by different EISs and resource adapters and shows how these factors can affect application design. The article concludes with Mikhail's tips for choosing the right transaction demarcation strategy and EJB deployment descriptor settings for your enterprise development scenario.