TNS errors using Oracle instant client

Question

I'm struggling to get my Oracle application working. I'm using the Oracle 11.2.0.4.0 instant client with a C++ application that is compiled using Visual Studio 2010. The machine is running Windows Server 2012 R2. The database is running on another machine.

The application is as basic as possible where I set up the environment and try to get the connection.

When trying to run it I'm faced with two different TNS errors:

ORA-12543: TNS:destination host unreachable (when using EZConnect string)

and

ORA-12154: TNS:could not resolve the connect identifier specified (when using the TNS name)

I'm running the application from the instant client directory, with ORACLE_HOME set as the same directory. I also export the directory of the oraocci11 dll files in the PATH variable.

What is strange is that sqlplus can connect without problems using both EZconnect and the TNS name (I have a tnsnames.ora in /network/admin).

What am I doing wrong?

Edit: Here is tnsnames.ora:

G2CLIENT =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 10.0.1.77)(PORT = 1521))
    )
  (CONNECT_DATA =
    (SERVICE_NAME = web)
  )
)

ORACLR_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
  (CONNECT_DATA =
    (SID = CLRExtProc)
      (PRESENTATION = RO)
    )
  )

WEB =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 10.0.1.77)(PORT = 1521))
  )
  (CONNECT_DATA =
    (SERVICE_NAME = web)
  )
)

and sqlnet.ora:

NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT, HOSTNAME)
SQLNET.AUTHENTICATION_SERVICES = (NTS)

The call that triggers the error is createConnection on a StatelessConnectionPool object which I have tried calling with different variations:

createStatelessConnectionPool("username","pwd","WEB")
createStatelessConnectionPool("username","pwd","10.0.1.77/WEB")
createStatelessConnectionPool("","","username/pwd@//10.0.1.77/WEB")

All of these seem to throw ORA-12154.

And as I mentioned above, sqlplus works fine.

Answer 1

suppose Orcl service already created but you can't communicate with them then do follow : you need to run your database service like "oracleServiceorcl" as a Administrator so that client server can communicate.

If any doubt then plz put error like ora- Any Digiy

Answer 2

I have figured it out. It seems there was a subtle dependency issue which resulted in a pretty irrelevant ORA message. The O11 instant client is not shipped with VS2010 lib/dll files. You need to download these separately, something I had done long ago and forgot about it. When compiling the app, I linked against the correct lib file but when running against the instant client I used the old oraocci11.dll file.

Thanks a lot for your help guys!