COM+ infrastructure services, also known as Enterprise Services, can be accessed from managed code. Enterprise Services applications consist of one or more serviced components that are managed classes derived from System.EnterpriseServices.ServicedComponent .
Serviced components are typically used to encapsulate an application's business and data access logic and are used when infrastructure services such as distributed transactions, object pooling, queued components, and others are required in an application's middle tier. Enterprise Services applications often reside on middle- tier application servers as shown in Figure 11.1.