UCP connects to Global Data Services in the same way that it connects to local services on an Oracle RAC. The service name in the connection string should be the name of the global service. The endpoint should be the endpoint of a GDS listener instead of the endpoint for the local, remote, or SCAN listener of a database.

A client must specify its region in the REGION parameter of the connection string. This is a new requirement for GDS. The region name is required because, in case of GDS, Run-time Load Balancing advisory is customized for particular regions. Following is an example of a typical connection string:

(DESCRIPTION=
  (ADDRESS=(GDS_protocol_address_information))
  (CONNECT_DATA=
   (SERVICE_NAME=global_service_name)
   (REGION=region_name)))

Like with local services, UCP can specify multiple GDS listeners in the same connection string for listener failover, load balancing, or both.

(DESCRIPTION=
  (ADDRESS_LIST=
    (LOAD_BALANCE=ON)
    (FAILOVER=ON)
    (ADDRESS=(GDS_protocol_address_information))
    (ADDRESS=(GDS_protocol_address_information)))
  (CONNECT_DATA=
   (SERVICE_NAME=global_service_name)
   (REGION=region_name)))

The REGION parameter is optional if only global service managers from the local region are specified in the client connection string. This is the case when there is only one region in the GDS configuration, or can be the case when there are multiple regions. But, it is not feasible to change the connection string of the an existing client designed to work with a single database. If the REGION parameter is not specified, then the client's region is assumed to be the region of the global service manager used to connect to the global service.

All GDS listeners in the preceding example belong to the same region where UCP is running, that is the local region. To provide high availability, when all GDSs in the local region are unavailable, you can specify the GDS listeners for the buddy region in additional ADDRESS_LIST descriptors.

(DESCRIPTION=
  (FAILOVER=on)
  (ADDRESS_LIST=
    (LOAD_BALANCE=ON)
    (ADDRESS=(global_protocol_address_information))
    (ADDRESS=(global_protocol_address_information)))
  (ADDRESS_LIST=
    (LOAD_BALANCE=ON)
    (ADDRESS=(global_protocol_address_information))
    (ADDRESS=(global_protocol_address_information)))
  (CONNECT_DATA=
   (SERVICE_NAME=global_service_name)
   (REGION=region_name)))

You do not need manual ONS configuration because UCP automatically retrieves the ONS connection information that is optimally customized for the UCP region from GDS.