Re: [enhydra] Postgres driver kills MySQL communication

["Michael Strapp" <mstrapp@xxxxxxxxxxxxx>]

Hi Petr,
   I can't say for sure whether this is a flaw in Enhydra or DODS.  I was
able to determine that the problem was caused by the fact that one of the
configuration classes (org.enhydra.dods.Common in the case of the
DatabaseManager.ConfigurationDir setting) was getting loaded by the system
classloader instead of the classloader created for each individual Enhydra
app - causing the static member variables in the class(es) to be shared
across all apps.
   Actually, I just had an idea that I hadn't thought of before - if you 
remove the jar(s) for the dods classes from the system classpath (or even 
move them out the enhydra5.1 tree to ensure that the regular Enhydra scripts 
can't find them), and explicitly add the dods jars to the Server.ClassPath[] 
setting in the .conf file for each Enhydra app, that would allow the DODS 
classes to be loaded only by the classloader belonging to each individual 
Enhydra app.  With the DODS project having been separated from the main 
Enhydra project, the multiserver hopefully wouldn't have a problem with that 
configuration - in which case, this would make each Enhydra app load the 
DODS classes with its own classloader and keep its own copy of the class 
definition (including any static member variables within the class).  In 
which case, that just might do the trick.

   If you end up giving this idea a try, let me know how it turns out.  In
my case, I've already worked around the problem for now, but I'll probably
revisit this and try it out myself at some point.

Regards,
Mike.

----- Original Message ----- 
From: "Petr Stehlik" <pstehlik@xxxxxxxxxx>
To: <enhydra@xxxxxxxxxxxxx>
Sent: Monday, October 25, 2004 10:36 AM
Subject: Re: [enhydra] Postgres driver kills MySQL communication


V Po, 25. 10. 2004 v 16:11, Michael Strapp píše:

Michael,

>    It sounds like you have multiple Enhydra apps running under the same
> multiserver with different database configurations.  Under DODS 5.x, some
> of
> the database settings are shared between applications (and declaring
> different values for them in different .conf files results in the value
> being used from whatever application happened to initialize last) - I
> found
> that this was the case for the DatabaseManager.ConfigurationDir setting a
> couple months back (see
> http://mail-archive.objectweb.org/dods/2004-07/msg00000.html) and I have
> since found that the DatabaseManager.ObjectIdColumnName and
> DatabaseManager.VersionColumnName settings are similarly affected.

now I know what you mean. Isn't this a shortcoming in the DODS? What
does the Enhydra team think?

Petr






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