On Sun, 18 Jun 2000, Avi Kivity wrote:
> > > - the exception model does not work: the container is
> > allowed to delay the
> > > database write until the end of the transaction, which
> > means that the
> > > exception occurs *after* all bean instance methods have
> > returned. This
> > > leaves the client with the nasty job of extracting the
> > SQLException from the
> > > RemoteException, parsing the vendor-specific message,
> > mapping from the
> > > database schema to the object level (that was the point of
> > CMP, wasn't it?),
> > > and finally recovering the beans which have been deleted due to the
> > > RemoteException thrown.
> >
> > A costly validation.
>
> Not really, since its the abnormal case. We only care about the common case.
> It's not an option, however, see points above.
>
> >
> > >
> > > - there is no support at the EB level to query the field
> > sizes. Even if I
> > > were to do this through JDBC, storing global values in EBs
> > is not permitted.
> > > Even if I knew the field sizes, they would probably be in bytes, not
> > > characters.
> >
> > Even if the container were to let you query for this this information
> > (mapping and DB schema), wouldn't this be expensive to do at runtime?
>
> You would only do this once.
>
> >
> > Secondly, such validation would be applicable only when DB fields are
> > directly mapped to information in the UI.
> >
> True. I don't like it either. What are people doing? Hardwiring the field
> lengths into the clients?
Is there any support for this from the O/R people, or in the JDO
spec? I've also seen some general purpose XML-configured code
used for the more coarse tests, like field length, but it does have
the disadvantage of divorcing the source of the constraint from the
declaration of the constraint...
Gary
>
>
> - Avi
> --
> s/\be(\w+)/e-\1/g;
>
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