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  • Status of entity relationships in App Engine?

    What is the status of entity relationships in a Roo application deployed to App Engine?

    Is it possible to create an application with --provider DATANUCLEUS --database GOOGLE_APP_ENGINE and use JPA one-to-many relationships? Is this where you would want to use --identifierType
    on your entity?

    Does anyone know about an example of a roo script that uses relationships and is built for app engine?

    If this is not possible - when will it be possible? Whithout relationships there must be a very limited interest in using Roo for App Engine applications. Is there a plan for this?

    I don't really understand the problem (if there is one), App Engine supports JDO and JPA, why would it be a problem to use JPA relationships created by Roo?

    Does anyone know anything about this? Please bring some clarity to this question.

  • #2
    Google App Engine (GAE) for Business announced at Google I/O will help here. The issue is not with Roo. GAE currently does not fully support JPA.


    • #3
      Ok, I didn't know that GAE doesn't fully support JPA. Thanks for that information.

      Will full support for JPA be available only in GAE for business?

      I was hoping that I could use the normal GAE. My application is a public web application. GAE for business sounds more like enterprise applications and intranets. It has many advanced features that I don't need.

      Is it correct that if I'm not interested in waiting for GAE for business, it's not possible to use Roo to create a GAE application (with relationships)?


      • #4
        Will "Spring Roo ROO-941 GAE DataStore relationship sugar" solve the problem? Is it possible to solve it in Spring Roo even if the current problem is that GAE doesn't fully support JPA?

        Is there possibly an easy workaround to the problem (getting relationships to work in GAE)?


        • #5
          Within Roo, my view is still that GAE should be considered like any other database that Roo supports and not have special treatment because of its current datastore features. The requirement to use DataNucleus 1.1.x is not ideal and I hope soon that GAE for Business will solve the relationships issue and that other ORM providers can be used without problems as well.

          Roo supports JPA and does a good job in my opinion with the popular SQL databases it supports now. With the impending database reverse engineering (DBRE) feature which I have been working on, this same support for SQL databases will be as good as what the Eclipse wizard can do, accepting all the defaults. However it won't work if pointed at a GAE datastore!

          I would ask you to hold out for a few more months