At a logical design level, IBM Cúram Social Program Management™ is platform independent. The concrete realization of a IBM Cúram Social Program Management™ application must, of course, be deployed in some "real world" environment. As already mentioned, business objects can be deployed in a variety of ways. One of the more important (and complex) environments is the online client/server environment. Online applications follow the Java EE™ architecture. This is a modern n-tier architecture with separate Presentation , Application and Persistence tiers. This logical three-tier architecture has become the standard for developing client/server applications. The separation of presentation, application logic, and persistent storage allows the very different concerns of these tiers to be considered in relative isolation and promotes easier design. IBM Cúram Social Program Management™ simplifies this concept even further by hiding much of the complexity of n-tier application development. This chapter looks at what's "under the hood" in the runtime architecture of IBM Cúram Social Program Management™ online applications.