[cdi-dev] [jsr342-experts] transactional interceptors and lifecycle methods

[JJ Snyder]

Bill Shannon asked me to forward

http://java.net/projects/javaee-spec/lists/jsr342-experts/archive/2013-03/message/7

to the EG.  I have pasted it here.  I will forward any feedback to Bill


    [jsr342-experts] transactional interceptors and lifecycle methods


We recently discovered an issue with the interaction between the
new @Transactional interceptors and the @PostConstruct method.
Should @PostContruct (and @PreDestroy) methods be transactional,
and if so how should the transaction type be controlled?

We'd like your feedback on this issue before Friday, March 15.

We've come up with four options for how this could work:

1. @PostConstruct is not transactional by default, but @Transactional
    is allowed.

         @Transactional(MANDATORY)
         public class MyBean {
             @PostConstruct
             public void postConstruct() {
                 // run with no transaction
             }

             public void myMethod() {
                 // uses @Transactional(MANDATORY)
             }
         }

         @Transactional(MANDATORY)
         public class MyOtherBean {
             @PostConstruct
             @Transactional(REQUIRES_NEW)
             public void postConstruct() {
                 // run with a new transaction
             }

             public void myMethod() {
                 // uses @Transactional(MANDATORY)
             }
         }

2. @PostConstruct is like any other method and inherits the class-level
    transaction attribute, but the developer must override the class-level
    attribute in some cases.

         @Transactional(MANDATORY)
         public class MyBean {
             @PostConstruct
             public void postConstruct() {
                 // FAILS because there can be no existing transaction context
             }

             public void myMethod() {
                 // uses @Transactional(MANDATORY)
             }
         }

         @Transactional(MANDATORY)
         public class MyOtherBean {
             @PostConstruct
             @Transactional(REQUIRES_NEW)
             public void postConstruct() {
                 // run with a new transaction
             }

             public void myMethod() {
                 // uses @Transactional(MANDATORY)
             }
         }

3. @PostConstruct is like any other method and inherits the class-level
    transaction attribute, but methods (like lifecycle callbacks) for
    which there can be no preexisting transaction context are handled as
    if they were REQUIRES_NEW when the MANDATORY attribute is specified
    (i.e., the attribute value handling here is special-cased).

         @Transactional(MANDATORY)
         public class MyBean {
             @PostConstruct
             public void postConstruct() {
                 // runs with a new transaction
             }

             public void myMethod() {
                 // uses @Transactional(MANDATORY)
             }
         }

         @Transactional(MANDATORY)
         public class MyOtherBean {
             @PostConstruct
             @Transactional(REQUIRES_NEW)
             public void postConstruct() {
                 // run with a new transaction, same as above
             }

             public void myMethod() {
                 // uses @Transactional(MANDATORY)
             }
         }

4. @PostConstruct can never be transactional.  UserTransaction can be
    used explicitly in the @PostConstruct method if needed.

         @Transactional(MANDATORY)
         public class MyBean {
             @PostConstruct
             public void postConstruct() {
                 // runs with no transaction context
             }

             public void myMethod() {
                 // uses @Transactional(MANDATORY)
             }
         }

         @Transactional(MANDATORY)
         public class MyOtherBean {
             @PostConstruct
             @Transactional(REQUIRES_NEW)
             public void postConstruct() {
                 // @Transactional is either ignored or causes runtime failure
             }

             public void myMethod() {
                 // uses @Transactional(MANDATORY)
             }
         }


#1 is most similar to stateful session beans in the current version of
the EJB spec.  When the ability to have transactional @PostConstruct
methods on stateful session beans was added to the EJB spec, it
couldn't be done by default due to compatibility.

#3 is consistent with Singletons in the current version of the EJB spec.

#4 is most similar to previous versions of the EJB spec.

We're currently leaning towards #3, since it seems consistent with other
interceptor use, but good arguments can be made for any of these choices.
We really need your feedback.

Let us know which choice you prefer before Friday, March 15.


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