I am thinking of how different persistence technologies like SQL-DB, Non-SQL-DB, plain-file-storage could flexibly be integrated in a Java EE application. I write here some directions and I would be pleased if you commented them.
In the integration tier we would use the DAO pattern to localize code for the the data access. This is quite straigthforward with entity classes for an SQL-DB. However, in addition to this DAO, there would also be a DAO for non-SQL-DB and a DAO for plain files available. The DAOs would be stateless session beans to ensure transaction capability, location transparency and concurrency. Nevertheless, the concurrency and location transparency seem to need to be implemented in the data tier for the non-SQL-DB and the plain file storage.
I am wondering whether the DAO design patter suits the best to implement the whole mechanism. I encountered also the JCA pattern which I am not familiar with and there is a lot of documentation on it. I would be pleased if you commented these ideas. Have you already had a similar task? Thank you for reading so far.