I have an ant task which will reverse engineer a database and create a
GAE LLAPI DAL.
Eg if your database is dept<----emp, then it will create DTO, DAO, BO
for emp and dept such that you can code
Dept dept = new Dept();
dept.setName("department 1");
Emp emp = new Emp(dept);
emp.setName("employee 1");
dept.persist();
emp.persist();
I'm currently updating the task to generate a Hibernate DAL such that
the above code can be used unchanged against either GAE LLAPI or an
RDBMS.
I have an Interface called CannedQueries, which needs to have an
implementing class for each DAL, and is instantiated using Guice.
So, the business code looks something like this:-
List employeesCalledSmith = cannedQueries.employeesCalled("Smith");
You need a version of the employeesCalled() method for each of GAE
LLAPI and Hibernate
Let me know if this helps and I'll try to package it up for you
best
Roy
On Nov 25, 4:17 pm, "K.Honsali" <[email protected]> wrote:
> Hi all,
>
> If my understanding of previous discussions is correct, we can resume
> from:
> - GAE/J is not relational (not full JDO too), and hence does not
> support sql features such as joins, like, not in ...etc
> - the solution is to de-normalize your tables ... or your mind..
>
> Now, suppose you have a quite big classic sql-based webapp which is
> multi-layered like a burger, so it is OK to change the Data Access
> Layer without affecting the other components, provided that the DAL
> calls and outputs remain the same.
> If you want to migrate this app to GAE/J, how would you do; knowing
> that beside CRUD queries, you have queries that execute (on the fly w/
> sql) up to a dozen joins ?
> a ) re-write your DAL in GAE/J's JDO, by denormalizing your tables (&
> your mind)
> b ) write your own sql wrapper, using full JDO and the low level
> datastore (can it be?)
> c ) none of the above
>
> Thanks for your CPU time :)
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