Re: [enhydra] Postgres driver kills MySQL communication

["Sinisa Milosevic" <sinisa@xxxxxxxxxxxxx>]

Hi,

There is a limit in DODS about usage of oidColumnName and versionColumnName
parameters.

See comments from source code (from CoreDataStruct.java)

  /**
    * The 'oid' and 'version' column names are made public so
    * they can be modified by StandardDatabaseManager.
    * These could be maintained in the LogicalDatabase but that
    * would require extensive modifications to DBTransaction and
    * DBQuery.
    * This means that you are currently limited to using the
    * same column names for all databases in applications using
    * multiple databases.
   */

    private static String oidColumnName = "oid";
    private static String versionColumnName = "version";

Currently DODS reads configuration from file and sets static values for oid
and version columns in CoreDataStruct. So last configured application
defines oid and version column names. If PostgreSQL database is the last and
it defines objectid as a oid column name, so your MySQL application deosn't
work.
That's  an 'old Enhydra-DODS feature' (difference is that in earlier version
static fields was in CoreDO). Dirty solution will be using objectid as a oid
column name for MySQl applications. Also we will add this problem on our
task list.

Regards,
Sinisa Milosevic
Together Serbia



----- Original Message -----
From: "Michael Strapp" <mstrapp@xxxxxxxxxxxxx>
To: "Enhydra Mailing List" <enhydra@xxxxxxxxxxxxx>
Sent: Monday, October 25, 2004 5:57 PM
Subject: Re: [enhydra] Postgres driver kills MySQL communication


> 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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>
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>
>


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