Pooling does several things. One, by having one bean per instance, you’re guaranteed to be threads safe (Servlets, for example, are not thread safe). Two, you reduce any potential startup time that a bean might have. While Session Beans are “stateless”, they only need to be stateless with regards to the client. For example, in … Read more
I’m very new to Java EE and I’m trying to understand the concept of Local interfaces and Remote interfaces. In the initial versions of the EJB specification, EJBs were “assumed” to be remote components and the only way to invoke them was to make a remote call, using RMI semantics and all the overhead it … Read more
Well, I’ve made some tests, and I’ve also tried the @Decorator way. This still seems to be the best one. @Entity bean and @Stateless bean are the same of the question, while I’ve changed the @Singleton bean as follows, also adding the classic timed cache: @Singleton public class RoomsCached { @Inject Rooms rooms; private List<Room> … Read more
I think you want to access an EJB application (known as EJB module) from a web application in Sun Application Server, right ? ok, let’s go. When you deploy an EJB into an application server, the application server gives it an address – known as global JNDI address – as a way you can access … Read more
I started from scratch. The only difference I can think of is that instead of making an EJB application, I just made an EJB module for the bean. Otherwise, I think it’s the same. structure: thufir@dur:~/NetBeansProjects$ thufir@dur:~/NetBeansProjects$ tree HelloLibrary/ HelloLibrary/ ├── build.xml ├── nbproject │ ├── build-impl.xml │ ├── genfiles.properties │ ├── private │ │ … Read more
Everything is behaving as specified. A stateless EJB delegates the call further to currently available instance in the pool. Apparently there’s only one which is not used concurrently (yet) and therefore all clients have the same chance to access the same instance in the pool. If you fire more HTTP requests concurrently on the servlet(s), … Read more
Until Java EE 7 only EJB was transactional and the @Transactional annotation didn’t exist. Since Java EE 7 and JTA 1.2 you can use transactional interceptor in CDI with @Transactional annotation. To answer your question about the best type of bean to use, the answer is CDI by default. CDI beans are lighter than EJB … Read more
The correct way to do this in your EJB is to use the ManagedExecutorService, which is part of the Concurrency Utils API (Java EE7). You shouldn’t be using any ExecutorService that is part of the java.util.concurrent in your enterprise code. By using the ManagedExecutorService your new thread will be created and managed by the container. … Read more
A few more details regarding the ConcurrentAccessException: as per the EJB spec, access to SLSB is synchronized by the app. server. However, this is not the case with SFSB. The burden of making sure that the SFSB is not accessed concurrently is on the application developer’s shoulders. Why? Well, synchronization of SLSB is only necessary … Read more
Remote client view When your EJB and its clients will be in a distributed environment – meaning EJBs and clients will reside on separate Java virtual machines. Example : EJBs hosted on a WebSphere Application Server and Servlets that consume EJB APIs hosted on a Tomcat server. Local client view Only when it is guaranteed … Read more