Applications begin a search by calling ct_ds_lookup with action as CS_SET.
ct_ds_lookup takes a CS_DS_LOOKUP_INFO structure as its lookup_info parameter that describes the search request. lookup_info−>objclass must point at a CS_OID structure that indicates the directory object class CS_OID_OBJSERVER. The other CS_DS_LOOKUP_INFO fields are currently unused and should be all passed as NULL.
ct_ds_lookup also takes a pointer to user-allocated data as its userdata parameter. When ct_ds_lookup invokes the application’s directory callback, the callback receives the same pointer value as an input parameter.
