On Sep 13, 10:06 pm, datanucleus <[email protected]> wrote:
> > I've discovered if I changed the datanucleus.ConnectionURL to
> > "appengine" I was able to get further
>
> You mean like the GAE/J documentation defines for you to do? and also
> the DataNucleus
> docshttp://www.datanucleus.org/products/accessplatform_1_1/appengine/supp...
>
> > This persistence provider doesn't seem to
> > allow a method such as isAgitated() to be in a entity class even if
>
> What method "isAgitated" ? There is nothing in the JPA spec with such
> a name. This is nothing to do with the persistence provider
>
> DataNucleus is a fully compliant JPA implementation for RDBMS. It is
> also a JPA implementation for XML, LDAP, OODBMS, GAE/J, HBase, ODF,
> and more. It has all features of JPA that are to be found in other
> implementations. Hibernate is an implementation of JPA for RDBMS, and
> nothing else (hence since you aren't using an RDBMS here I fail to see
> the way you can apply it to your problem with GAE/J)
>
> Please specify which exact JPA behaviour causes "headache"
>
> --Andy (DataNucleus)
I guess the "headache" is that I had a backend server piece using JPA
(Hibernate implementation) with a Postgresql database working just
fine. Now that I want to use the GWT toolkit to develop some AJAX
front-end capabiltiy, I having to go back and revisit my server-side
data storage. I expected the AJAX develop tools to allow me to keep
these two concerns (AJAX UI and backend storage) somewhat separate.
I'm not opposed to using Data Nucleus since it implements JPA (what
I've already coded to) but I'm still having a devil of a time figuring
out how to configure it to work with may existing annotated POJOs and
my exising Postgresql database. All the documentation seems to
assume (or perhaps dictate) that I going to use the preconfigured Data
Nucleus "appengine" with JDO.
My specific issues are:
1) I put a convenience method in a POJO named "isInProximity
(aPeerPojo)" and even though is also takes a parameter and has an
@Transient annotation, I get errors about having declared an
"InProximity" field in MetaData but this field doesn't exist. If I
rename the method to not start with "is" this error goes away.
2) I'm getting errors with my @GeneratedValue
(strategy=GenerationType.SEQUENCE ...). I believe this is because its
using a database that has a different strategy for creating object
identifiers. That is, is not using my Postgresql database but using
some appengine database instead. So, I'm still struggling to get all
the configuration setup so it will just work with the backend
datastorage mechanism I had working before I downloaded the eclipse
plugins to develop some AJAX frontends.
I'd even consider migrating from Postgresql if I had a better idea of
just how much work is involved and how this "appengine" database will
perform once it has tens of gigabytes of data in it (as long as I can
still use JPA). I really just want to get this data storage issue
reconciled as quickly as possible so I can get back to developing AJAX
frontends. As I mentioned previously, I don't currently plan to
mashal any of these database POJOs to the client. I'm planning to
just use XML for client/server communication.
Jeremy
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