Hi Muhammad, here is a quick response:
- read the datanucleus documentation on JDO for a general background - read the Datastore, Queries, Indexes and Relationships documentation from App Engine (we use Java API) for the set of restrictions they place on using JDO with the GAE datastore. - avoid using GAE specific types and APIs (e.g. Don't use "Key", use "Long", etc). That is what leads to most of the restrictions on what you can and can't do with JDO on datastore..... such as having both Parent and child persistent objects with Long keys...etc - I expect that JDO on MySql has some restrictions also. I am not familiar with them, but our developer ran into a few of them. - we are looking at using namespaces for the datastore, and might create an emulation of it on MySql to keep our application code portable... >From that you get a kind of sub-set of what can and can´t be done with JDO on GAE/MySql, and leads to you having to manage child object storage via keys manually. Then off course, set up your project to be able to be built and ran on Tomcat/MySQL with little extra effort, and test on that other platform regularly and as part of your test and release process. It IS extra work, no doubt about that, even after the initial learning and experimenting. More coding, and more testing.... If there was a common place to share experiences in these attempts at portability (e.g. a wiki?) then we'd be happy to contribute to it, and learn from it... not sure to what extend Google (with it´s cloud portability goals) would be willing to host/contrinbute to that???? -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
