Thank you very much for your answers.
So, if I understood you well, I can let Tapestry inject the Session in my
DAOs this way:
class MyDAO {
private final Session session;
public MyDAO (Session session) {
this.session = session;
}
public void performSomeOperationOnSession() {
...
}
}
...and I can rest assured multiple concurrent requests that call
performSomeOperationOnSession() will use different sessions because the *
session* injected in the DAO is a per-thread-proxy. Is this right?
But, as Kalle says, I suppose we should use HibernateSessionSource when we
explicitly create multiple threads. Or even in this case injecting Session
is enough? (Because maybe it doesn't matter if threads are created
explicitly by me or implicitly by the web container).
Ferran
On Tue, Feb 28, 2012 at 2:09 AM, Thiago H. de Paula Figueiredo <
thiag...@gmail.com> wrote:
> On Mon, 27 Feb 2012 20:55:28 -0300, Ferran Maylinch <
> ferranmayli...@gmail.com> wrote:
>
> Hello,
>>
>
> Hi!
>
>
> We are currently using both approaches but we don't know exactly when to
>> use each one.
>> When should we inject a HibernateSessionSource into the DAO and create
>> Sessions with source.create() and when should we directly inject a
>> Session?
>>
>
> Unless in some very specific scenarios, I'd just inject a Session. In
> Tapestry-Hibernate, Session is a perthread service: in other words, in
> different threads, different session instances are provided. In the same
> thread, all Session injections get the same instance.
>
>
> In our application we have some DAOs calling other DAOs. What should I
>> inject to them: a HibernateSessionSource or a Session? Or should I pass a
>> Session to the DAO methods?
>>
>
> Same answer as above: just inject Session.
>
>
> Or DAOs calling other DAOs is discouraged?
>>
>
> If you're working with two tiers (web and DAO), I'd say no, it isn't
> discouraged. If you're working with three tiers (web, business rules and
> DAO), I'd say it is discouraged and you'd better have a business rule class
> call another one instead.
>
>
> And a further question would be: what happens if a class starts several
>> threads using Sessions and transactions. How should we handle that?
>> Sometimes we suffer deadlocks but we can't spot the cause.
>>
>
> Now you're going out of topic here. IMHO, this is a pure database and
> connection question, and this is the Tapestry web and IoC framework mailing
> list. :)
>
> --
> Thiago H. de Paula Figueiredo
> Independent Java, Apache Tapestry 5 and Hibernate consultant, developer,
> and instructor
> Owner, Ars Machina Tecnologia da Informação Ltda.
> http://www.arsmachina.com.br
>
