Oracle Transparent Application Failover (TAF)

TAF is based on OCI (Oracle Call Interface). So every client using OCI can/may profit from TAF.
JDBC Thick requires an Oracle Client to be installed, hence you have OCI and therefore TAF.
JDBC Thin does not require an Oracle Client to be installed (just the appropriate JAR files) and is not based on OCI, hence NO TAF.

You need to install the Oracle instant client first.

Below is a client-side TAF setup

tnsnames.ora

RACPROD =
  (DESCRIPTION=
    (FAILOVER = ON)
    (ADDRESS=
      (PROTOCOL=TCP)
      (HOST=rac-scan.leavemealone.local)
      (PORT=1521)
    )
    (CONNECT_DATA=
      (SERVER=dedicated)
      (SERVICE_NAME=prod.leavemealone.local)
      (FAILOVER_MODE = (TYPE = SELECT)(METHOD = BASIC)(RETRIES = 10)(DELAY = 5))
    )
  )

SQL*Plus with TAF

sqlplus accdb@racprod

SQLcl with TAF

sqlcl accdb@jdbc:oracle:oci:@(DESCRIPTION=(FAILOVER=on)(ADDRESS=(PROTOCOL=TCP) (HOST=rac-scan.leavemealone.local)(PORT=1521))(CONNECT_DATA= (SERVICE_NAME=prod.leavemealone.local)(FAILOVER_MODE = (TYPE = SELECT)(METHOD = BASIC)(RETRIES = 10)(DELAY = 5))))

SQL Developer with TAF
Change connection type to Advanced and then put this in Custom JDBC URL

jdbc:oracle:oci:@(DESCRIPTION=(FAILOVER=on)(ADDRESS=(PROTOCOL=TCP) (HOST=rac-scan.leavemealone.local)(PORT=1521))(CONNECT_DATA= (SERVICE_NAME=prod.leavemealone.local)(FAILOVER_MODE = (TYPE = SELECT)(METHOD = BASIC)(RETRIES = 10)(DELAY = 5))))

Below is a server-side TAF setup

Add and review TAF service

srvctl add service -d orcl -s prodtaf.leavemealone.local -m BASIC -e SELECT -z 180 -w 5 -j LONG -r "ORCL1,ORCL2"
-pdb prod
srvctl start service -d orcl -s prodtaf.leavemealone.local
srvctl config service -d orcl -s prodtaf.leavemealone.local
Service name: prodtaf.leavemealone.local
Server pool:
Cardinality: 2
Service role: PRIMARY
Management policy: AUTOMATIC
DTP transaction: false
AQ HA notifications: false
Global: false
Commit Outcome: false
Failover type: SELECT
Failover method: BASIC
TAF failover retries: 180
TAF failover delay: 5
Failover restore: NONE
Connection Load Balancing Goal: LONG
Runtime Load Balancing Goal: NONE
TAF policy specification: NONE
Edition:
Pluggable database name: prod
Maximum lag time: ANY
SQL Translation Profile:
Retention: 86400 seconds
Replay Initiation Time: 300 seconds
Drain timeout:
Stop option:
Session State Consistency: DYNAMIC
GSM Flags: 0
Service is enabled
Preferred instances: orcl1,orcl2
Available instances:
CSS critical: no

tnsnames.ora

RACPROD =
  (DESCRIPTION=
    (ADDRESS=
      (PROTOCOL=TCP)
      (HOST=rac-scan.leavemealone.local)
      (PORT=1521)
    )
    (CONNECT_DATA=
      (SERVER=dedicated)
      (SERVICE_NAME=prodtaf.leavemealone.local)
    )
  )

SQL*Plus with TAF

sqlplus accdb@racprod

SQLcl with TAF

sqlcl accdb@jdbc:oracle:oci:@(DESCRIPTION= (ADDRESS=(PROTOCOL=TCP) (HOST=rac-scan.leavemealone.local)(PORT=1521))(CONNECT_DATA= (SERVICE_NAME=prodtaf.leavemealone.local)))

SQL Developer with TAF
Change connection type to Advanced and then put this in Custom JDBC URL

jdbc:oracle:oci:@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP) (HOST=rac-scan.leavemealone.local)(PORT=1521))(CONNECT_DATA= (SERVICE_NAME=prodtaf.leavemealone.local)))

To verify the connection is actually using TAF

SELECT inst_id,
         machine,
         program,
         username,
         logon_time,
         failover_type,
         failover_method,
         failed_over
    FROM gv$session
ORDER BY logon_time DESC;