To further optimize access times, frequently requested information is automatically loaded to a topic of memory in the client computer, the DUA cache, and can be overwritten again if it is not used within a certain interval of time. The cache may be periodically updated. The GDS administration program specifies the period. It can also specify that certain data is never written to the cache, or that certain data that is transferred must under no circumstances be deleted, unless it is deleted by the user. Because the DUA cache is not subject to any access control, GDS ensures that only the information that everybody is allowed to read is stored.
The GDS package includes the OM class DSX_C_GDS_CONTEXT to support additional service controls for caching. DSX_C_GDS_CONTEXT is a subclass of DS_C_CONTEXT. As such, it inherits all the standard X.500 attributes associated with DS_C_CONTEXT, in addition to its own OM attributes related to caching. Refer to GDS API: Concepts and Overview for more information on how to manage the DUA cache by using XDS.