[teiid-dev] Translators in the "vdb.xml" file.

[Michael Walker]

Somewhat new to the translator nomenclature/architecture change...does this mean that each VDB will have its own Translators, with their own connection pools, and its own classloader, ensuring that VDBs will not share translator instances among each other?

If so, then this would be tremendously useful from a deployment perspective. You could finally deploy a VDB and not have to choose whether to use embedded binding properties or pre-existing properties created by a pre-existing VDB. Deploying a new version of a translator would not require ripping all previous versions out and rebuilding them from scratch, which is very tedious and requires downtime. You would have better guarantees about the level of service a connection pool would provide, since there's no possibility of two VDBs sharing a pool. 


________________________________________
From: teiid-dev-bounces at lists.jboss.org [teiid-dev-bounces at lists.jboss.org] On Behalf Of Steven Hawkins [shawkins at redhat.com]
Sent: Tuesday, May 25, 2010 11:31 AM
To: Van Halbert
Cc: teiid-dev at lists.jboss.org
Subject: Re: [teiid-dev] Translators in the "vdb.xml" file.

This is a change toward simple and focused.  With the environmental information held by a resource adapter connection factory the remaining properties of a translator are not expected to change.  It simplifies deployment greatly to have the vdb be self contained than maintaining translators as another global entity.

In any event the deployment of a custom translator is also greatly simplified from before, and should now become as easy as placing the JAR with your ExecutionFactory in the deploy directory.

If a custom translator is changed (same name/class, but with different property definitions), then the expectation is that the developer either has considered the impact of the migration, such that the old translators property sets are compatible with the new.  If a new name is given and the old custom ExecutionFactory is removed, then a forced migration would occur that requires the change of affected vdbs.

I don't necessarily see that as a limitation.  We are steadily moving down the path where from dynamic vdb or even designer perspective the physical model metadata is tied directly to the translator used.  This is especially true for LDAP and Salesforce, but is even true for JDBC as native types, column names, etc., are not the same across all source types.  Only the loopback translator is a jack of all trades, but is of limited usefulness for anything other than basic queries.

So to state this a different way, change your translator == change you physical model.

----- Original Message -----
From: "Van Halbert" <vhalbert at redhat.com>
To: "John Verhaeg" <jverhaeg at redhat.com>
Cc: teiid-dev at lists.jboss.org
Sent: Tuesday, May 25, 2010 1:11:14 PM GMT -06:00 US/Canada Central
Subject: Re: [teiid-dev] Translators in the "vdb.xml" file.

I vote the designer doesn't push the creation of a translator by adding additional translator properties to the vdb.xml file.  If the user created a custom connector, they'll already be dealing with the task of deploying it to server(s).   Also, if this information is stored in the vdb (call it A) and then if the original custom translator is changed (and replaced) and then vdb "A" is  redeployed, don't we now have a usability issue that has to be resolved on whether to replace the existing translator properties or not.   Carrying stale information in the vdb has caused us problems in the past, so I would hope we wouldn't head back down that road on the first release.

I think this first release should be simple and focused.    If the usability in the next release drives it in this direction, then so be it.


On May 25, 2010, at 12:39 PM, John Verhaeg wrote:

> On May 25, 2010, at 11:21 AM, Ramesh Reddy wrote:
>
>> What I forgot mention in the earlier is, if user chooses one of the
>> default "translators", then there is not really any need to define the
>> XML fragment for the Translator at all inside the vdb.xml. Which I
>> suspect in majority of the cases. Only when user wants to alter the
>> default behavior, Teiid would need the additional translator fragment.
>
>
> So presumably there will be some property on the translators that indicates whether its a default translator?
>
> Thanks,
>
> JPAV
>
>
>
>
> _______________________________________________
> teiid-dev mailing list
> teiid-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/teiid-dev

Van Halbert
Principal Software Eng.
Red Hat, Inc.
------
vhalbert at redhat.com






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