Thanks for replying to my question. I have figured out how EJB works with servlets now, I am not a very experienced developer and I learn through examples. I inject session beans (@EJB) into my servlets and database manupulations are kept in session beans. While reading about these issues I came across Java 6EE where as I understood EJBs are introduced in web container as web beans. Should be easier to figure out for newcomers like me:) Thanks
Jay D. McHugh-3 wrote: > > Sorry for the late reply to this. > > Geronimo should not allow you to add container managed entity managers > to servlets. They would not be thread safe. > > I haven't looked at the example in a while - but I believe it is using a > stateless session bean to access the entity manager. That is perfectly > acceptable (and correct)... > > I just took a look at the example and it does in fact use a stateless > bean (AccountBean). So, that is why it is able to use container managed > persistence. > > I don't think that it would actually make projects simpler to move the > data access logic into each of the servlets that need it. For me at > least, centralizing the logic into session beans means that I am forced > to consider exactly what I will be doing with the data and only write > the code once to do it. > > Hope that helps, > > Jay > > tornike wrote: >> Yes, but if it's in their example maybe it's OK for Geronimo to use >> container >> managed EntityManager with the servlet and there won't be any threading >> issues. If it's true then we wouldn't need any EJB's in the project and >> simply communicate to JPA entities even when using container managed >> EntityManager. As far as I know this method is discouraged but if it's ok >> to >> do in Geronimo it would greatly simplify many projects. >> >> >> >> Fredrik Jonson-3 wrote: >>> In <25221488.p...@talk.nabble.com> tornike wrote: >>> >>>> EntityManager is not thread safe and it should not be injected into >>>> the >>>> servlet. (container managed one) However in the example of ejb-JPA >>>> >>>> http://cwiki.apache.org/GMOxDOC21/container-managed-persistence-with-jpa.html >>>> >>>> I have tested the example works without problems so are there >>>> conditions >>>> when it can be done or am I understanding it the wrong way? >>> I'd say the example is wrong or at least careless. So I'm also >>> interested >>> if someone thinks otherwise. >>> >>> If I would have done it I'd inject a EntityManagerFactory in the servlet >>> and >>> acquired a new EntityManager from the pool for each request to doGet >>> method: >>> >>> public class Example extends HttpServlet { >>> @PersistenceUnit >>> private EntityManagerFactory emf; >>> >>> @Override >>> protected void doGet(HttpServletRequest request, HttpServletResponse >>> response) >>> throws ServletException, IOException { >>> EntityManager em = emf.createEntityManager(); >>> // do stuff >>> >>> -- >>> Fredrik Jonson >>> >>> >>> >> > > -- View this message in context: http://www.nabble.com/EntityManager---Servlets-tp25221488s134p25461383.html Sent from the Apache Geronimo - Users mailing list archive at Nabble.com.
