The default Data Service provides a stateless, query-based interface to retrieve information about VMODL objects, as defined by the vSphere Web Services API. The default Data Service interface can access data from vCenter Server. The Data Service accesses various services on vCenter Server, including the Inventory and Property Collector services.User interface components, such as Flex data views, act as Data Service clients. These clients retrieve information by creating Data Service queries. The Data Service processes each query and returns a set of result objects.If your vSphere Web Client extensions require data from a different source, either within vCenter Server or outside vCenter Server, you can extend the Data Service by creating a Data Service Adapter. A Data Service Adapter provides a way for you to use Data Service queries to retrieve non-VMODL data, such as custom object data.