[deepamehta-devel] creating topics from listener method

[Jörg Richter]

Hi Robert,

> On 04 Dec 2017, at 18:27, Robert Schuster <robert.schuster.rs01 at gmail.com> wrote:
> 
> [...]
> 
> When this code runs it will actually cause an exception because there is
> no transaction context.
> If it were a normal rest method I'd add @Transactional and all would be
> fine.

Yes, due to the way Jersey resource filter factories work the @Transactionsal annotation can only be used directly at a JAX-RS resource method.

> However I don't have this option, so I thought I'd do a TX myself
> and surrounded the above code with:
> 
>         DeepaMehtaTransaction tx = dm4.beginTx();
> 
>         // code from above
> 
>         tx.finish();
>         tx.success();
> 
> Unfortunately that does not do anything. I don't see errors in the log
> but the actual topic is not created either.

success() must be executed *before* finish().

success() marks the tx as successful.
finish() commits if marked successful, otherwise does rollback.
It's best to put finish() in a finally block to be executed for sure, that is in error case and in regular case.

The usual pattern is:

        DeepaMehtaTransaction tx = dm4.beginTx();
        try {
            ....
            tx.success();
        } catch (Exception e) {
            throw new RuntimeException("...", e);
        } finally {
            tx.finish();
        }

Your code always rolls back.

Cheers,
Jörg

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