Reconnecting to an oracle DB

[Fabien Bergeret]

My application uses a CustomRegistry on WAS 5 to ensure its security. Works fine most of the time, but if the db is not present at startup, the registry is supposed to loop every 10s to see if the db is back.
The first time, I have the following exception :
java.sql.SQLException: Exception d'E/S: The Network Adapter could not establish the connection
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:179)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:333)
at oracle.jdbc.driver.OracleConnection.<init>(OracleConnection.java:404)
at oracle.jdbc.driver.OracleDriver.getConnectionInstance(OracleDriver.java:468)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:314)
at java.sql.DriverManager.getConnection(DriverManager.java:543)
at java.sql.DriverManager.getConnection(DriverManager.java:194)

Ok, fine, the network cable was purposely unplugged. I plug it back, and every 10s, it still have the same exception : i cannot connect to the database once it has fumbled ...
I can still connect with sqltools, so the db is up. If I stop the application and restart it, it works, so the url, the user and the pass are ok.
Any idea ?
Thanks

[Jeanne Boyarsky]

Fabien,
Can you post the code segment you use to try the connection? It sounds like you might be repeatedly trying the same connection that doesn't work. The alternative is to close the connection and get a new one or use connection pooling.

[Fabien Bergeret]

Here is the code :

  
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.Statement;
 
public class TestReconnexionBDD {
private static Connection initCon() throws Exception {
 
Driver driver =
(Driver) Class
.forName("oracle.jdbc.driver.OracleDriver")
.newInstance();
DriverManager.registerDriver(driver);
Connection con =
DriverManager.getConnection(
"jdbc:oracle:thin:@aixdev1:1521:modoxd01",
"user",
"pass");
return con;
 
}
public static void main(String[] args) throws Exception {
//Connection con = initCon();
 
System.out.println("Stop the net");
Thread.currentThread().sleep(10000);
try {
initCon();
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("Start the net");
Thread.currentThread().sleep(10000);
 
initCon();
System.out.println("End");
}
}

When I run the class without the network, I have the following trace (which is perfectly normal):

java.sql.SQLException: Exception d'E/S: The Network Adapter could not establish the connection
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:179)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:333)
at oracle.jdbc.driver.OracleConnection.<init>(OracleConnection.java:404)
at oracle.jdbc.driver.OracleDriver.getConnectionInstance(OracleDriver.java:468)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:314)
at java.sql.DriverManager.getConnection(DriverManager.java:543)
at java.sql.DriverManager.getConnection(DriverManager.java:194)
at TestReconnexionBDD.initCon(TestReconnexionBDD.java:35)
at TestReconnexionBDD.main(TestReconnexionBDD.java:61)

After this exception, I start the network before the second attempt (it is really started since I can connect to the database with SQLTools), and I still have the same exception ...

[ August 11, 2004: Message edited by: Fabien Bergeret ]

[ August 11, 2004: Message edited by: Fabien Bergeret ]

[ August 11, 2004: Message edited by: Fabien Bergeret ]
[ August 11, 2004: Message edited by: Fabien Bergeret ]

[Julian Kennedy]

Hi Fabien,

As Jeanne says, close the connection (con.close()) when you catch the exception. That should solve the problem. Otherwise your subsequent calls to getConnection() are probably just picking up the broken one.

You might need a little more than 10 seconds for it to recover and connect happily.

Jules