It’s not rare the scenario where you end up needing to run some code during the initialization of a given class or of an application. This article will present a few options in how to achieve this task.
Run code when the class is loaded
In this scenario, you want to run some code when a given class is loaded by the JRE, but you want that code to be executed only once, regardless of the number of instances of that class. For this, you can use a static initialization block.
Continue reading “Running code at application/class startup”
In this post we will see a brief introduction about the Spock test framework and how to integrate it with Maven and Eclipse.
Spock is a framework used to write tests using the Groovy language and its adoption has been increasing lately. Although Groovy is the language you must use to write your tests with Spcok, it can be used for both Groovy and Java applications and is compatible with most of the Java IDEs, including Eclipse.
The idea of writing the tests using Groovy can be seen as an obstacle for some Java developers that are not familiar with Groovy. However, the knowledge required in Groovy is quite basic and the Spock documentation itself is very helpful with this question. I myself, right now, know very little about Groovy and this hasn’t been an issue to write tests with Spock.
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Continuing with the subject presented in the first part of this article, let’s talk a little more about asynchronous processing with ExecutorServices. In this second part, let’s approach the following use case.
Our software will receive and process a batch of transactions. After processing this batch, the system must create a “summary” of the processing, pointing individually the number of processed transactions successfully and with error. This summary could be sent to some other system, for example, that could then analyze the success rate of this transactions batch or something like that.
Continue reading “Asynchronous processing with ExecutorServices – Part 2”
With state-of-the-art machines with a lot of processors, it’s essential that you be able to build software that can get the most out of these resources. What’s the purpose of having a super computer with 16 processors if your software is executed sequentially in a single-thread? Messaging systems, like JMS and AMQP, can be really useful to distribute your processing. However, in some scenarios, these technologies may be overkill, once besides bringing some overhead related to adding a message broker to the architecture, we may just want to efficiently use all the processors of the machine, splitting a task that would be executed in a single-thread in a set of smaller tasks that can be executed in parallel by multiple threads. Prior to Java 5, we had to create/manage manually the Threads, which wasn’t a pleasant task. But with Java 5, things got easier with the new Executor Services.
Continue reading “Asynchronous processing with ExecutorServices – Part 1”
This post is related to a presentation I gave (in Portuguese) for a Brazilian tech event called TDC (The Developer’s Conference) in 2012. The topic of this presentation was how to use AMQP in a Java application, using the RabbitMQ messaging system and Spring.
You can check the code in the GitHub.
Creating automated tests for JEE applications has always been a challenge, once it requires a running container to provide all the services the application needs to work properly and that the tests need to be executed.
The Arquillian framework was born to make this job a lot easier to be executed. Your main goal is to provide a powerful test platform responsible of taking care of many aspects while testing JEE applications, such as start a container, deploy an application in the container, run the tests and stop the container. It also allows that your test classes can be enriched with annotations like @Inject, @EJB and @Resource, among others. This way, one can easily create real integration tests. Arquillian also allows users to choose either JUnit or TestNG to create and execute the tests, besides allowing the same test cases to be executed in different containers, such as JBoss, Glassfish and Tomcat.
This post’s goal is not to discuss the benefits in writing automated tests -TDD or not- but, instead, focus on how to use Arquillian through a practical example.
Continue reading “Testing JEE6 applications with Arquillian”