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From Rick Hillegas <rick.hille...@oracle.com>
Subject Re: using ClientDataSource on Java 6
Date Tue, 09 Nov 2010 16:36:33 GMT
Knut Anders Hatlen wrote:
> Rick Hillegas <rick.hillegas@oracle.com> writes:
>
>   
>> The Admin Guide says that you can use the ClientDataSource class on
>> all Java SE platforms, including Java 6:
>> http://db.apache.org/derby/docs/10.6/adminguide/adminguide-single.html#cadminnsdatasources
>>
>> I think that this may work if verification is lazy and does not notice
>> that ClientDataSource does not satisfy the full Java 6 contract for
>> javax.sql.DataSource (ClientDataSource does not implement
>> java.sql.Wrapper). I believe that a runtime with aggressive
>> verification could fail to load ClientDataSource.
>>
>> Does this sound right to you?
>>
>> Elsewhere in our user documentation, we do advise applications to use
>> the *40 DataSources when running on Java 6.
>>     
>
> ClientDataSource40 extends ClientDataSource, so if a JVM fails to load
> the ClientDataSource class, I suppose it won't be able to load
> ClientDataSource40 either.
>
> It would also fail to load the Connection/Statement/ResultSet classes in
> any JDBC 3.0 driver, so the backward-compatibility story for such a JVM
> would be poor.
>
>   
That sounds right. I will stop worrying about this one.

What should we do about the issue Dag brings up? The Admin guide tells 
people to use ClientDataSource. That advice is repeated in the 
Developer's guide: 
http://db.apache.org/derby/docs/dev/devguide/devguide-single.html#rdevresman79556 
But the javadoc advises people to use DataSource implementations 
specific to the JDBC level of their VM. The discrepancy between the user 
guides and the javadoc is confusing people and that is why I kicked off 
this thread. I think that the verbiage in the Developer's guide is the 
clearest statement about what is expected to work. Should we just add 
that verbiage to the javadoc headers for our public DataSource 
implementations?

Thanks,
-Rick

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