Luke! User the source Luke! ;)
Eelco
On 10/21/05, Dorel Vaida <[EMAIL PROTECTED]> wrote:
> If you don't want to go Spring or you're not allowed to (some middle
> management still doesn't get it :-)) ) you do what they do :-D w/o using
> the whole Spring framework. To extract the transaction and exception
> logic from the code you might want to use callbacks. What I mean by that:
>
> define a TransactionCallback interface with one method:
>
> public interface TransactionCallback {
> public Object transactionalOperation(Session session) throws
> HibernateException;
> }
>
> Than you build a template for running transcations, template that will
> handle transaction demarcation and exception handling:
>
> public class Template {
> public Object execute(TransactionalCallback callback){
> try {
> //open session if necessary, use the threadLocal pattern
> //begin tx
> callback.transactionalOperation(openedSession)
> //end tx
> // close session if necessary
> } catch (Hib exception) {
> // handle hibernate exception
> }
> }
> }
>
> Than in the application code you go:
>
> Template template = new Template();
> // get an object
> Serializable id ... ;
> User user = (User) template.execute(new TranssactionalCallback(){
> public Object transactionalOperation(Session session) throws
> HibernateException {
> return session.get(User.class, id);
> }
> });
> }
>
> Please note that this is not complete code, you have to work more on it
> to make it production ready, I was just ilustrating the ideea. Spring
> support doesn't resume to this, they offer a lot more but if you just
> want to get TX/exception out of your business code you might consider
> the example above. To get the complete picture please take a look into
> the Spring code, or read Rod Jonhson's J2EE w/o EJBs to see a better
> description of this aproach. Also if you use Spring with Hibernate take
> a look at Hibernate3 and spring 1.2.X because some things are pretty
> different, I hear.
>
> Good luck :-D
>
> Igor Vaynberg wrote:
>
> >We already discussed that. If you want to separate transaction management
> >from wicket use a dao/service layer that lives inside spring and lets spring
> >handle transaction management. That way you have declarative transaction
> >management with retries and all that good stuff. Check out wicket-phonebook
> >from wicket-stuff for a good starting point. If you are using jdk5 there are
> >features that significantly shorten and simplify the spring configuration
> >file.
> >
> >-Igor
> >
> >
> >
> >
> >>-----Original Message-----
> >>From: [EMAIL PROTECTED]
> >>[mailto:[EMAIL PROTECTED] On Behalf Of Gili
> >>Sent: Thursday, October 20, 2005 9:58 AM
> >>To: [email protected]
> >>Subject: Re: [Wicket-user] Wicket, Hibernate and
> >>StaleObjectStateException
> >>
> >>
> >> Fair enough, I have something similar going right now.
> >>But this still leaves one problem:
> >>
> >> If StaleObjectStateException is thrown inside
> >>Form.onSubmit() I am forced to handle it (and retry) inside
> >>onSubmit() as opposed to
> >>(ideally) handling it outside Wicket and retrying the entire
> >>HTTP request. Right now I have a whole bunch of transaction
> >>blocks defined
> >>*inside* my application code which is a disaster. It kills
> >>readability as well as making my application aware of
> >>transactions when ideally it shouldn't have to care about it.
> >>
> >> In http://www.hibernate.org/42.html they write: "Our
> >>goal really is to remove any transaction demarcation code
> >>from the data access code" which is exactly what I'm trying
> >>to accomplish...
> >>
> >>Gili
> >>
> >>Igor Vaynberg wrote:
> >>
> >>
> >>>Instead of doing this:
> >>>
> >>>Onbeginrequest() { mysession=factory.opensession();
> >>>mysession.begintransaction(); }
> >>>
> >>>Session getSession() { return mysession; }
> >>>
> >>>Do this:
> >>>
> >>>Onbeginrequest() { mysession=null; }
> >>>
> >>>Session getSession() { if (mysession==null) {
> >>>mysession=factory.opensession(); mysession.begintransaction(); }
> >>>return mysession; }
> >>>
> >>>Then when an error occurs just reset mysession back to null
> >>>
> >>>
> >>and next
> >>
> >>
> >>>time you need one you will get a fresh one
> >>>
> >>>
> >>>-Igor
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>>-----Original Message-----
> >>>>From: [EMAIL PROTECTED]
> >>>>[mailto:[EMAIL PROTECTED] On Behalf Of Gili
> >>>>Sent: Wednesday, October 19, 2005 11:44 PM
> >>>>To: [EMAIL PROTECTED]
> >>>>Subject: [Wicket-user] Wicket, Hibernate and
> >>>>
> >>>>
> >>StaleObjectStateException
> >>
> >>
> >>>>Hi,
> >>>>
> >>>> I'm trying to figure out how to handle
> >>>>
> >>>>
> >>StaleObjectStateException in
> >>
> >>
> >>>>the context of Wicket. Using the current-state pattern as reference
> >>>>(http://www.hibernate.org/42.html) if a
> >>>>
> >>>>
> >>StaleObjectStateException is
> >>
> >>
> >>>>thrown, I'd like to rollback the transaction, close the
> >>>>
> >>>>
> >>session, open
> >>
> >>
> >>>>a new session and transaction and retry the operation.
> >>>>
> >>>>
> >>Ideally I want
> >>
> >>
> >>>>to keep this logic completely out of the Wicket code. I
> >>>>
> >>>>
> >>simply don't
> >>
> >>
> >>>>see how this can be done.
> >>>>
> >>>> For example, say I have a page containing a Form and
> >>>>Form.onSubmit() is invoked and in its body
> >>>>
> >>>>
> >>StaleObjectStateException
> >>
> >>
> >>>>is thrown. Following the "Session per HTTP request"
> >>>>
> >>>>
> >>pattern, we're in
> >>
> >>
> >>>>a new HTTP request (I
> >>>>think) but I don't think Wicket will invoke beginRequest() and
> >>>>endRequest() before and after Form.onSubmit(). Even if it did, I'd
> >>>>have no way to signal to Wicket to retry the
> >>>>onSubmit() operation by catching the exception outside it.
> >>>>
> >>>> So on the one hand, I don't want to catch the
> >>>>
> >>>>
> >>exceptions inside the
> >>
> >>
> >>>>Wicket code. On the other hand, I can't retry the operation
> >>>>
> >>>>
> >>if I catch
> >>
> >>
> >>>>the exception outside the Wicket code.
> >>>>
> >>>> Your advice would be appreciated.
> >>>>
> >>>>Thank you,
> >>>>Gili
> >>>>--
> >>>>http://www.desktopbeautifier.com/
> >>>>
> >>>>
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> >>>
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> >>>
> >>--
> >>http://www.desktopbeautifier.com/
> >>
> >>
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> >
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