Using JTA transaction in JAX-RS ContainerResponseFilter, any side effects?

Question

I have a provider where I can always read Entities but I was never write some until I set the @TransactionManagement(TransactionManagementType.CONTAINER) on class level and the @Transactional on the overridden filter method.

@Provider
@Priority(value = 1)
@TransactionManagement(TransactionManagementType.CONTAINER)
public class SecurityUsageResponseFilter implements ContainerResponseFilter
{
    @PersistenceContext(unitName = "MyAppPersistenceUnit")
    private EntityManager entityManager;

    @Override
    @Transactional
    public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) throws IOException
    {
        //code

        updateUserAndHeaderInformation(id, responseContext);

        //code
    }

    private void updateUserAndHeaderInformation(Object userId, ContainerResponseContext responseContext)
    {
        //This ALWAYS work
        RestrictedUsers user = entityManager.find(RestrictedUsers.class, userId);

        //Only works when transactions are explicitly set
        user.setLastTransferToken(newTransferToken);
        user.setLastObfuscationId(newObfuscationId);
    }
}

My question is: Are there maybe any side effects when the filter method is suddenly transactional? Usually transactions are only used in service methods, but here I'm using a provider any maybe there is some different behaviour in the background which could interfere things I didn't think about yet?

Answer 1

It may work but I wouldn't do that.

Your filter should be kept lean and these operations should be delegated to the service layer, which is responsible for demarcating the transactions.