Connecting to a SQL Server using Windows Authentication

[Mike Domondon]

Hi,

I have a plugin that connects to an SQL Database to gather information for
some metrics. It works okay until I restart the plugin from the RHQ UI
(Agent>Operations>New>Restart
Agent>Schedule)

After this, when the plugin tries to connect to the Database I get this
error:
java.sql.SQLException: I/O Error: SSO Failed: Native SSPI library not
loaded. Check the java.library.path system property

ntlmauth.dll is used by Windows Authentication and exists in the path. I
did some research on the web, it seems, Windows and Java hove some issues
when it comes to loading DLLs...

from http://www.eclipsezone.com/articles/eclipse-vms/
<http://www.eclipsezone.com/articles/eclipse-vms/>


*"It's worth bearing in mind that Windows and Java have some issues when it
comes to loading DLLs. A DLL can only be loaded once in a VM and only
associated with one ClassLoader. If you have two ClassLoaders, and they
attempt to load the same DLL, then the second one will fail and not be able
to execute any native code. As a result of this, you cannot have two
bundles that attempt to load the same native code in Eclipse. This will
also apply if the bundle is updated or restarted, because the old
ClassLoader may retain a reference to the DLL whilst the new one starts.
This is a Windows-specific problem that doesn't appear to manifest itself
on other operating systems." *
*
*
Has anyone encountered this problem before? Is there a workaround for this
in RHQ?

Thanks,
Mike
*
*
*
*

[John Mazzitelli]

I have not encountered that or noticed that before, but I don't do much work on
Windows.

A workaround could be to not use that Restart Agent operation on the RHQ Agent resource
itself - use the launcher restart operation instead.

If you read the description of that operation that you used, it specifically says it
doesn't restart the VM:

"Shuts down the agent's comm layer and plugin container and starts them up again.
This does *not* restart the agent's VM - use the launcher services to do that."

As per the link you posted - if you don't restart the VM, Windows will have problems
reloading that DLL. So don't use that operation to restart.

Instead, the workaround may be to use the child launcher resource to do the restart (which
WOULD restart the VM and presumably avoid this problem you see).

Since you are on Windows, I think you'd want to restart your agent using the
agent's child service of the type "Java Service Wrapper Launcher" which has
an operation "Restart". The description is "Restarts the Java Service
Wrapper and the agent it contains.  This will completely kill the agent VM process (if it
is running as this service) and then attempt to restart it. If the agent executing this
operation will quickly die, no confirmation will be available as to the success or failure
of this operation."

----- Original Message -----
>  Hi,
>  
>  I have a plugin that connects to an SQL Database to gather information for
>  some metrics. It works okay until I restart the plugin from the RHQ UI (
>  Agent>Operations>New>Restart Agent>Schedule)
>  
>  After this, when the plugin tries to connect to the Database I get this
>  error:
>  java.sql.SQLException: I/O Error: SSO Failed: Native SSPI library not loaded.
>  Check the java.library.path system property
>  
>  ntlmauth.dll is used by Windows Authentication and exists in the path. I did
>  some research on the web, it seems, Windows and Java hove some issues when
>  it comes to loading DLLs...
>  
>  from http :// www . eclipsezone . com / articles / eclipse - vms /
>  
>  "It's worth bearing in mind that Windows and Java have some issues when it
>  comes to loading DLLs. A DLL can only be loaded once in a VM and only
>  associated with one ClassLoader. If you have two ClassLoaders, and they
>  attempt to load the same DLL, then the second one will fail and not be able
>  to execute any native code. As a result of this, you cannot have two bundles
>  that attempt to load the same native code in Eclipse . This will also apply
>  if the bundle is updated or restarted, because the old ClassLoader may
>  retain a reference to the DLL whilst the new one starts. This is a
>  Windows-specific problem that doesn't appear to manifest itself on other
>  operating systems."
>  
>  Has anyone encountered this problem before? Is there a workaround for this in
>  RHQ?
>  
>  Thanks,
>  Mike
>  
>  
>  
>  _______________________________________________
>  rhq-users mailing list
>  rhq-users(a)lists.fedorahosted.org
>  https://lists.fedorahosted.org/mailman/listinfo/rhq-users
>

[Ken Hancock]

Hi John,

Good advice.  Part of the problem, however, is I -think- that during a
failover of the rhq server the same thing is happening.

Does this sound possible?

In the cases we've seen this the logs had rolled so it's not clear
exactly what caused the problem but could definitely see the effect if
the agent restarted.

Ken


On Thu, Apr 11, 2013 at 8:54 AM, John Mazzitelli <mazz(a)redhat.com&gt; wrote:
>  I have not encountered that or noticed that before, but I don't
> do much work on Windows.
>
>  A workaround could be to not use that Restart Agent operation on the RHQ Agent resource
> itself - use the launcher restart operation instead.
>
>  If you read the description of that operation that you used, it specifically says it
> doesn't restart the VM:
>
>  "Shuts down the agent's comm layer and plugin container and starts them up
> again. This does *not* restart the agent's VM - use the launcher services to do
> that."
>
>  As per the link you posted - if you don't restart the VM, Windows will have problems
> reloading that DLL. So don't use that operation to restart.
>
>  Instead, the workaround may be to use the child launcher resource to do the restart
> (which WOULD restart the VM and presumably avoid this problem you see).
>
>  Since you are on Windows, I think you'd want to restart your agent using the
> agent's child service of the type "Java Service Wrapper Launcher" which has
> an operation "Restart". The description is "Restarts the Java Service
> Wrapper and the agent it contains.  This will completely kill the agent VM process (if it
> is running as this service) and then attempt to restart it. If the agent executing this
> operation will quickly die, no confirmation will be available as to the success or failure
> of this operation."
>
>  ----- Original Message -----
> > Hi,
> >
> > I have a plugin that connects to an SQL Database to gather information for
> > some metrics. It works okay until I restart the plugin from the RHQ UI (
> > Agent>Operations>New>Restart Agent>Schedule)
> >
> > After this, when the plugin tries to connect to the Database I get this
> > error:
> > java.sql.SQLException: I/O Error: SSO Failed: Native SSPI library not loaded.
> > Check the java.library.path system property
> >
> > ntlmauth.dll is used by Windows Authentication and exists in the path. I did
> > some research on the web, it seems, Windows and Java hove some issues when
> > it comes to loading DLLs...
> >
> > from http :// www . eclipsezone . com / articles / eclipse - vms /
> >
> > "It's worth bearing in mind that Windows and Java have some issues when it
> > comes to loading DLLs. A DLL can only be loaded once in a VM and only
> > associated with one ClassLoader. If you have two ClassLoaders, and they
> > attempt to load the same DLL, then the second one will fail and not be able
> > to execute any native code. As a result of this, you cannot have two bundles
> > that attempt to load the same native code in Eclipse . This will also apply
> > if the bundle is updated or restarted, because the old ClassLoader may
> > retain a reference to the DLL whilst the new one starts. This is a
> > Windows-specific problem that doesn't appear to manifest itself on other
> > operating systems."
> >
> > Has anyone encountered this problem before? Is there a workaround for this in
> > RHQ?
> >
> > Thanks,
> > Mike
> >
> >
> >
> > _______________________________________________
> > rhq-users mailing list
> > rhq-users(a)lists.fedorahosted.org
> > https://lists.fedorahosted.org/mailman/listinfo/rhq-users
> >
>  _______________________________________________
>  rhq-users mailing list
>  rhq-users(a)lists.fedorahosted.org
>  https://lists.fedorahosted.org/mailman/listinfo/rhq-users 


-- 
Ken Hancock | System Architect, Advanced Advertising
SeaChange International
50 Nagog Park
Acton, Massachusetts 01720
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Office: [phone] |  ken.hancock(a)schange.com | hancockks | hancockks


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[John Mazzitelli]

>  Good advice.  Part of the problem, however, is I -think- that during
> a
>  failover of the rhq server the same thing is happening.
>  
>  Does this sound possible? 
I don't think that would be the cause of problem. I say this because a failover to
another server doesn't affect shutting down the internal plugin container. At most
what it would do is shutdown the communications sender object until a server became
available - but the plugin container and plugins continue to run normally.

If the plugin container is shutdown and restarted (but the agent JVM remains running),
that's when classloaders are discarded and new ones created (and based on your earlier
post and that link you provided, that appears to be the cause of the issue - when a VM
stays up but a new classloader is asked to load a DLL that was previously loaded).