On 9/21/05, Kathey Marsden <[EMAIL PROTECTED]> wrote:
> Yes, I think the idea is that network server handle the null by
> constructing this SQLException to return to the client for the failed
> connection which the client could use to determine the problem and
> behave appropriately.
>
> In general for any failed connection
>
> Client Sends ACCRDB
> Server tries to connect and gets null from driver.connect() or
> other exception.
> Server sends RDBAFLRM and appropriate SQLCARD (SQLException)
>
> For the case where driver.connect() returns null on the server side we
> have to return an SQLCARD with the RDBAFLRM that the client can use
> and differentiate this special kind of error so it can return null from
> its own connect() method.
I have changed the ClientDriver to look for the specific exception
returned from Network Server for null connection. If it gets this
exception, it inturn returns null to the caller.
> Thinking about it a bit more, perhaps an RDBAFLRM and a null SQLCARD
> would work for that purpose instead of constructing an SQLException to
> send with the RDBAFLRM and maybe makes more sense here.
The protocol requires a RDBAFLRM to be followed by a SQLCARD. A
SQLCARD with null SQLException is being returned at many places by the
server and so I think this cannot be used here. I could not find a
specific message type in the protocol to return information about null
connection.
> The alternate
> method is to go back to expecting the client itself to reject any
> unacceptable urls.
Since network server gives NPE with certain URLs, I think this has to
be solved on the server side.
>Regardless, probably the localization is not
> important because the error would never get to the user.
With checks added to ClientDriver, the error will not get to the user.
Please see if these changes are okay. I will post a patch after tests complete.
1. Network server checks for null connections returned by
InternalDriver and throws a specific exception. It sends back RDBAFLRM
and SQLCARD with this exception.
//In org.apache.derby.impl.drda.Database.makeConnection(Properties)
if(conn == null){
throw new SQLException("No suitable driver","08001");
}
2. ClientDriver.connect checks for this exception and returns null.
try{
conn =
new
org.apache.derby.client.net.NetConnection((org.apache.derby.client.net.NetLogWriter)
dncLogWriter,
java.sql.DriverManager.getLoginTimeout(),
server,
port,
database,
augmentedProperties);
}
catch(java.sql.SQLException e){
if(e.getMessage().indexOf("No suitable driver") != -1){
//No suitable driver exception means a null connection
was
//returned to Network server by InternalDriver
conn = null;
}
else
throw e;
}
return conn;
Thanks,
Deepa
