Re: Wrapping persistence strategy exceptions into RollerExceptions

[Markus Fuchs]

Hi Mitesh,

In case of the JPA layer, we should just wrap PersistenceExceptions. 
Declaring a method to throw checked RollerExceptions does not mean that 
RuntimeExceptions can't occur. It's up to the user to handle 
RuntimeExceptions, or not.

Thanks,

-- markus.

Mitesh Meswani wrote:

Hi Markus,

I think it should be enough to make sure that persistence related 
exceptions are caught and rethrown as RollerException as you have 
shown in your example below.

Do you think catching all RuntimeExcpetion, like SQLExceptions or 
NullPointerExceptions (which most probably should be due to bugs in 
the persistence provider's code) and rethrowing them as (checked) 
RollerExceotion would add any value?

Thanks,
Mitesh

Markus Fuchs wrote:

Thank you!

Mitesh, Craig,

Shall catch all RuntimeExceptions then and re-throw them as 
RollerExceptions?

-- markus.

Allen Gilliland wrote:

Markus,

I don't think there is really a perfect answer to your question, but 
I think that in general any exceptions that are specific to the 
persistence implementation should be caught and rethrown as a 
RollerException.  Whether or not to catch RuntimeExceptions could 
probably be debated, but I think in general it's preferable to catch 
them and rethrow as a normal RollerException.

-- Allen


Markus Fuchs wrote:

Hi all,

I'm helping Mitesh implementing the persistence layer abstraction
for roller.

I'm wondering, if strategy specific exceptions should be wrapped into
RollerExceptions by the strategy implementation. All persistence
layers throw RuntimeExceptions: PersistenceExceptions for JPA,
JDOExceptions for JDO or HibernateExceptions for Hibernate.

Should strategy specific RuntimeExceptions be wrapped into checked
RollerExceptions? E.g. in JPAPersistenceStrategy, we could implement
something like:

  public void flush() throws RollerException {
      try {
          EntityManager em = getEntityManager(false);
          if (isTransactionActive(em)) {
              em.getTransaction().commit();
          }
          em.close();
      } catch (PersistenceException e) {
          throw new RollerException(e);
      }
  }

Also, should be same be done for other persistence layer related 
exceptions?
E.g. SQLExceptions or NullPointerExceptions?

Thanks,

-- markus.