UTL_TCP - connection loss

Question

Hi guys,
I would need a help with UTL_TCP package...
Oracle version is:
SELECT * FROM V$VERSION;
Oracle Database 11g Release 11.2.0.2.0 - 64bit Production
PL/SQL Release 11.2.0.2.0 - Production
"CORE    11.2.0.2.0    Production"
TNS for Linux: Version 11.2.0.2.0 - Production
NLSRTL Version 11.2.0.2.0 - Production
I have a package which handles communication with another system over tcp. In the package, there is a private global variable of type UTL_TCP.Connection which holds the connection record after I open a connection. I normally send data using UTL_TCP.Write_Text function.
This works fine until a moment when the connection probably breaks or something else happens. After that, when I try to call UTL_TCP.Write_Text, it fails because the global structure holding connection details is already null - namely remote_host and remote_port are suddenly set to null. Calling UTL_TCP.Write_Text then throws an exception:
ORA-29260: network error: not connected
Please note the description...
Does anyone has an idea how can this happen???
I know that these fields are set to null when I call UTL_TCP.CLOSE_CONNECTION, but this I don't call at all (only at the end when closing the application). I have put a logging into my function which holds the call to UTL_TCP.CLOSE_CONNECTION to be 100% sure that this isn't invoked and it isn't.
In the documentation to UTL_TCP package I see:
remote_host
Name of the remote host when connection is established. NULL when no connection is established.
remote_port
Port number of the remote host connected. NULL when no connection is established.
So I thought that when there is a connection break because of any reason, maybe Oracle itself could set these fields to null...
I have created a test package with just 2 functions - one for opening a connection, one for sending some data. Now, I connect to some listening application, send some data, then I close or kill that remore application and try to send some data to it.
To me is very strange that when I do that, I am always able to make two successful calls of UTL_TCP.Write_Text function and the third call always fails with following error:
ORA-29260: network error: TNS:lost contact
See that the ORA number is the same, but description is different.
Is there any difference between these two errors - how is it possible that same ORA error has different description?
How is it possible that remote_host and remote_port are suddenly set to Null?
Thanks a lot for help,
Dan

Answer 1

I found the problem.
1) The difference between two descriptions of ORA-29260 is that
network error: not connected - is displayed when trying to send the data and the connection structure is null, meaning we are not connected to the remote system
network error: TNS:lost contact - is displayed when we were connected (connection structure is not null), but the connection is lost for some reason
2) The problem with connection structure suddently set to null was happening because we were using different DB session from time to time. So it was happening that we were trying send the data in session where we were not connected to remote process.