Sounds good. I also think I'll focus much of my attention on the low- level API, so this could be very useful!
Regards, Richard On Oct 22, 11:37 am, Nacho Coloma <icol...@gmail.com> wrote: > Hi all, > > We have been developing a persistence framework for the AppEngine > Datastore based on the raw DatastoreService API. For our (simple) > persistence case, both JDO and JPA were a bit overkill as we were > spending a significant amount of time jumping through hoops to make > our application roll, but at the same time the Datastore API was a too > low-level solution to be usable. > > So we reinvented our wheel. In two days. > > SimpleDS is a light wrapper around the DatastoreService APIs that > provide a simple interface for java persistent classes. It does not > include fancy stuff or any super features, it's just the > DatastoreService ported to a world where Java entities can be > persisted directly (using a subset of JPA annotations). This is _not_ > a JPA/JDO replacement, and will never be. But we have been using it > for some weeks and are quite happy with it. > > Any kind of feedback from the AppEngine community would be welcome. > Before calling the typical "but we already have JPA/JDO!" argument, > please notice the following: > > * There are lots of considerations in a relational database that do > not apply to AppEngine. This allows a specific solution to be > simplified big time. Just see the depth of your typical stack trace to > understand what I am talking about. > * Solutions can be designed for specific cases that are common > practice in AppEngine but do not apply to a relational database. See, > for example, saving entities with a parent instance. > * Transactions also behave a bit differently, where a "one size fits > all" approach would probably not be the best solution. > > To better ilustrate with an example, these are some typical tasks > performed with SimpleDS: > > Retrieve instance: > FooBar bar = entityManager.get(key); > > Transform from Google Datastore Entity to java and viceversa: > Entity entity = entityManager.datastoreToJava(bar); > > Save generating a primary key, with a parent instance: > FooBar bar = new FooBar(); > entityManager.put(parentKey, bar); > > More can be seen here:http://code.google.com/p/simpleds/wiki/SimpleTasks > > Any discussion about the current API state is welcome. This entire > thing was rolled in two days and tested in a couple of weeks so there > should be some bugs in between. > > It is important to keep in mind the current list of limitations: > > * Only the Key class is a supported primary key. > * IN and != are not supported (yet). I have big concerns about > supporting this, performance-wise. > * Relationships are not supported. You can use Keys and collections of > Keys for that purpose. > * Transactions are not yet included. We are not yet sure about how to > proceed here. > > As I said, this is not conceived to become a feature-complete JPA > replacement, so please don't treat it like that. > > Best regards, > > Nacho. --~--~---------~--~----~------------~-------~--~----~ 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-java@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 -~----------~----~----~----~------~----~------~--~---
