In this tutorial, we’ll explore how to use the @Startup and @Singleton annotations in Jakarta EE applications. These annotations allow us to initialize components during application startup and ensure that they are available throughout the application’s lifecycle. We’ll cover the basics of each annotation, how to use them together, and provide examples to illustrate their usage.
EJB 3
How to configure distributed EJB Timers
Do you need to scale your EJB Timers at its bests ? WildFly 27 supports a new mechanism for storing your Timers in a cluster: distributed EJB Timers. In this article we will learn how to configure it in no time.
How do I lookup an EJB in a JAR file from a Web application?
This article will teach you how you can look up an EJB (inside a JAR file) from a Web application (inside a WAR file).
How to make all your EJB clusterable in JBoss/WildFly
This article will discuss how to enable clustering for Enterprise Java Beans (EJB) with WildFly application server or JBoss EAP.
How to disable passivation for SFSB in WildFly
When a Stateful Bean is experiencing a period of inactivity, the EJB container maydecide to remove it from memory temporarily. This process is called passivation. Most of thestate of the EJB is saved automatically except for transient fields. When the EJB is restored,the stateless EJB has its original content except for the transient fields. Passivation … Read more
EJB 3 tutorial : Session Beans
Enterprise JavaBeans (EJB) technology is an Enterprise technology for developing business components in a component-based, enterprise Java application. EJB technology is generally viewed as powerful and sophisticated. The technology helps developers build business applications that meet the heavy-duty needs of an enterprise. In particular, applications built using EJB and other Enterprise technologies are secure, scale … Read more
Singleton EJB tutorial
If you need to make sure you are exposing an Enterprise Java Bean as a Singleton, there is a simple approach which requires adding the @Singleton annotation on your EJB. As the name implies a javax.ejb.Singleton is a session bean with a guarantee that there is at most one instance in the application. Until … Read more
How to code EJB interceptors like a pro
EJB 3 interceptors provide the bean developer with fine grained control over the method invocation flow. In this tutorial we’ll see how to code server side EJB Interceptors and how to define Global EJB server side interceptors (WildFly 18 or newer). An interceptor is a method that you can interpose in the invocation flow of … Read more
Using Bean Managed Transactions (BMT) in Java EE applications
In a Bean Managed Transaction (BMT), the code in the EJB or Message Driven Bean explicitly marks the boundaries of the transaction. Although beans with container-managed transactions (CMT) require less coding, they have one limitation: When a method is executing, it can be associated with either a single transaction or no transaction at all. If this … Read more
Message Driven Bean example
A Message Driven Bean (MDB) is an asynchronous message consumer. The MDB is invoked by the container as a result of the arrival of a message at the destination that is serviced by the MDB. In this tutorial you will learn how to code a simple MDB and and a Client to interact with.