16.5.1 Service Data Objects
Service Data Objects (SDO) is a data programming architecture that - in contrast to all other technologies that are currently available - unifies data programming across data source types. Using SDOs, application programmers can uniformly access and manipulate data from heterogeneous data sources, including relational databases, XML data sources, Web services, and Enterprise Information Systems.
Figure 16-9 Flexibility of Service Data Objects
To realize this simple and unified way to handle data, Service Data Objects add a new abstraction layer that is placed on top of existing data access frameworks like EJBs, JDO, or direct JDBC data access. Therefore, Service Data Objects do not replace existing frameworks, instead, they use them as data mediators under the cover. In fact, Service Data Objects are becoming a standard way to implement the Business Delegate and Data Transfer Object patterns.