David R. Heffelfinger

  Ensode Technology, LLC

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Java EE Course Trip Report

I just came back from teaching a Java EE class in San Francisco.

The course lasted two days, and it covered the most commonly used Java EE technologies and API's such as JavaServer Faces (JSF), Contexts and Dependency Injection (CDI), Enterprise JavaBeans (EJB), the Java Persistence API and the Java Message Service(JMS). The course also touched on Bean Validation and the Java API for RESTful Web Services (JAX-RS).

The students were veteran Java developers and architects, ranging from around 5 to 18 years of experience. There were a few students that had use EJB's back in the J2EE era, some that had used earlier versions of JSF (1.x) and some that had been focusing on Spring for their server side Java development.

None of the students had use modern versions of EJB or JSF, they were very impressed on how much easier modern versions of these frameworks are compared to their Java EE counterparts.

Since we had only two days, we only covered the basics of each technology, such as Facelets markup for JSF. For CDI, we covered context (scope) annotations and dependency injection for CDI. We mentioned additional CDI features such as qualifiers, stereotypes and interceptor binding types.

The different Bean Validation annotations were covered, pointing out how simple it is to do validation using just a few simple annotations. As far as EJB's go, I covered the different type of session beans, such as Stateless, Stateful, and Singleton session beans; as well as Message driven beans. For EJB's we went a bit deeper, covering things such as transaction management, interceptors for Aspect Oriented Programming (AOP) and the EJB timer service.

When talking about JPA, the class covered basic JPA annotations such as @Table and @Column, as well as one-to-many, many-to-one, many-to-many and one-to-one entity relationships. We also covered eager vs lazy fetching, and the advantages and disadvantages of each approach. We ended the JPA topic with a discussion of the Java Persistence Query Language (JPQL) and the JPA Criteria API.

I overheard some comments from the students, for example, one mentioned "EJB's are cool", which I completely agree. Another student noted that there isn't anything in Java EE that he cannot accomplish with Spring, which, while it may be true that the end result is the same, fails to take into account that the amount of work to get this end result tends to be a lot less with Java EE.

There were hands-on labs for the students to practice the concepts taught in class. I chose NetBeans as the IDE for the exercises, since it comes bundled out of the box with everything needed to build complete applications, such as a Java EE compliant application server (GlassFish), and a fully functional RDBMS (JavaDB). Not many of the students had previous NetBeans experience, however most of them were able to finish the exercises (which were simple, but complete Java EE applications) in about 30 minutes or so.

While discussing the hands-on labs, I provided some NetBeans tips, such as the ability to generate boilerplate code (Alt-Ins), generate JPA entities from an existing database, and the NetBeans JPQL editor, which provides code completion when developing JPQL queries.

All in all, a great experience. I don't get to teach as often as I'd like, it is a nice change of pace from my day to day job developing real-life Java EE applications.


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© David R. Heffelfinger