Hi all, one of my company (Tirasa) customers asked Fabio Martelli (in CC) and me to start exploring the integration between OpenJPA and MS SQL Azure federations.
After some work we came out with [1], a sample webapp with persistence layer (managed by OpenJPA) on MS SQL Azure; moreover, this sample code makes profit of federations [2], a way to perform table partition, close to the "sharding" concept. SQL Azure federations were initially considered as mappable to OpenJPA slices: in fact, both refers to 'sharding', however with slight different meaning. OpenJPA slices provide their own mechanism to handle at application level distributed queries, data distribution and data replication1; SQL Azure federations, instead, push such aspects to database configuration level and empowers the ability to change some of these at runtime. For example, with OpenJPA slices can be configured so that records from table Person with field id value < 500 will be handled by slice1, while the rest will be handled by slice2, where slice1 and slice2 are two separated databases. This breaks the SQL Azure federations model, because the Person table of this example can be dynamically split at runtime, thus generating one or more federation members at persistence level. This implies that the actual federation member for a given record * cannot be determined by configuration -- as OpenJPA slices require, but only at runtime; * cannot be chosen at application level but is enforced by persistence level. At the end, SQL Azure federations provide an additional scalability layer and can then be seen as complementary to OpenJPA slices, rather then opposite. If anyone is interested, we also wrote a simple wiki page [3] about how to get our demo code up an running. Any feedback is welcome. Our customer is currently evaluating whether to extend this feasibility study with a complete implementation and would also like us to contribute such code back to OpenJPA community. Fabio Martelli and I are already ASF committers and PPMC members at Apache Syncope [4], IdM solution with persistence based on OpenJPA. WDYT? Regards. [1] https://github.com/Tirasa/protojpasqlazure/ [2] http://msdn.microsoft.com/en-us/library/windowsazure/hh597452.aspx [3] https://github.com/Tirasa/protojpasqlazure/wiki/Setup [4] http://incubator.apache.org/syncope/ -- Francesco Chicchiriccò ASF Member, Apache Cocoon PMC and Apache Syncope PPMC Member http://people.apache.org/~ilgrosso/
