Few days ago, during our regular code review, one of my colleagues raised a question what would happen — and if it’s even possible — when a CDI Observer (so a method with parameter annotated @Observes) would be invoked multiple times at the same time for different event instances. In other words, after producing few events, is it possible that ...

Java EE 7 has been recently accepted by the Executive Committee. This means that soon we should have Java EE 7 application servers available on the market. One of the specifications that constitutes Java EE 7 is JMS 2.0. Some interesting improvements were introduced since version 1.1. JMS has a lot of weird stuff like:

JGroups is Bela Ban‘s piece of software for reliable message exchange that is highly configurable and can use either TCP or UDP as a transport protocol. Basically – you run the JGroups on number of clients, they form a cluster and they can send and receive messages within the cluster. JGroups is used internally by JBoss Infinispan. Infinispan, however, unlike ...

Being in EJB and JPA world using CMT (Container Managed Transactions) is very comfortable. Just define few annotations to demarcate transaction boundary (or use the defaults) and that’s it – no fiddling with manual begin, commit or rollback operations. One way to rollback your transaction is to throw non-application exception (or application exception with rollback = true) from your EJB’s ...

JPA specification defines few types of EntityManagers / Persistence Contexts. We can have: extended and transactional-scoped EntityManagers, container-managed or application-managed EntityManagers. JTA or resource-local EntityManager, Besides the above distinction, we also have two main contexts in which EntityManager / Persistence Context can exist – Java EE and Java SE. Not every option is available for Java EE and not every ...

Despite the fact that EJB inheritance sometimes uses Java inheritance — they’re not always the same. Just as you could read in my previous post, EJB doesn’t have to implement any interface to expose a business interface. The other way around is also true — just because EJB is implementing some interface or extending other EJB doesn’t mean it exposes ...

This post will talk about possible ways of defining EJB views using annotations (I’ll just mention about using EJB Deployment Descriptor at the end.) I’ll focus on the most current EJB 3.1 views omitting legacy local, remote and home interfaces. Therefore, we can choose between: remote business interface view, local business interface view, no-interface view. I won’t discuss functional differences ...