Re: [aerogear-dev] TODO server app observations

These seems like good points for discussion and/or issues for jira. The only one that concerns me with my quick look is generating serializers at compile time. Build time generation is one of the area's we wanted to avoid in general. For the other items I think jira's would be appropriate as your understanding of the AS and SLSB's would be useful to capture these concerns or potential bugs. -Jay On Oct 9, 2012, at 10:25 AM, Marko Strukelj wrote: > > I’ve been looking into TODO app to get a better understanding of > how aerogear.js works in a browser, and how we could abstract > server-side into something we could call ‘aerogear-server’ as > opposed to TODO app. > > Here are some observations: > > > - The *Endpoint classes are SLSB, but use extended persistence > context [1] > > Extended persistence context is not supported on Stateless session > beans per JPA spec [2]. > > The reason is that stateless beans are not singletons or contextual > objects (i.e. CDI scoped) but are pooled instances, so you can > receive a different one for each call that you make. That would > mean that you could get a different EntityManager instance each > time, with possible uncommitted state from another method call by > another client. It would be impossible to do consistent > persistence across multiple invocations with that kind of random > behaviour. Also if ten requests hit at the same time there would > be ten instances of EntityManager, and ten separate persistence > contexts, and since they are extended and ‘never’ cleared (EJB > container decides, behaviour is unspecified) - we have ten memory > leaks. > > It looks like AS7 doesn’t much care if you use EXTENDED annotation > in a SLSB - it will happily comply (and create a memory leak for > you), whereas some other app servers will break on deployment [3], > and Scott Marlow concedes it should probably be a deployment error > [4], so maybe one day this would also break on AS7. > > > > - Method joinTransaction() only makes sense on application-managed > entity manager > > We are using container-managed entity manager - one that gets > injected - as opposed to one retrieved by calling > EntityManagerFactory.createEntityManager() method (that would be > application-managed). Call to joinTransaction() is therefore a > no-op, and should be removed [5][6][7]. > > > - Custom serializers look like plumbing > Would be good to have a way to autogenerate them during compile > based on annotations. Also, for the purpose of autogenerating > entities for the client based on server data definitions > (metadata) we need to use those same definitions during > serialization. This is the most obvious point where > aerogear-server as a server-side framework comes to play. > > > [1] > https://github.com/aerogear/TODO/tree/picketbox/server/src/main/java/org/... > [2] > http://stackoverflow.com/questions/2547817/what-is-the-difference-between... > [3] https://community.jboss.org/thread/196404 > [4] https://community.jboss.org/message/721988#721988 > [5] > http://docs.oracle.com/javaee/6/api/javax/persistence/EntityManager.html#... > [6] http://docs.oracle.com/javaee/5/tutorial/doc/bnbqw.html > [7] > http://docs.jboss.org/hibernate/orm/4.0/hem/en-US/html/architecture.html#... > > > - marko > > > _______________________________________________ > aerogear-dev mailing list > aerogear-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/aerogear-dev _______________________________________________ aerogear-dev mailing list aerogear-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/aerogear-dev