Category Archives: java

Enhance OpenJPA entities with Gradle

OpenJPA has a Maven plugin but doesn’t provide a gradle plugin (yet?) but build-time enhancing is still a nice solution to ensure your entities will behave correctly whatever deployment you choose (in a plain TomEE the built-in javaagent does the work well but in embedded tests it is not guaranteed).

Is that a reason to abandon Gradle? Maybe not yet ;).

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Oh My js! Server side javascript for java developers?

Javascript tooling set was enriched a lot these last years: npm, bower, gulp, grunt, … but most of them work on nodejs and need a certain amount of knowledge before being able to get anything from it.

For a Java developer it can be complicated and tempting to do a plain JSP instead of embrassing javascript.

Making javascript development easy can only be done in the case of a framework with a lot of defaults cause by nature you need to develop in an exploded fashion (by module) fr the maintenance and aggregate them at the end for performances reasons (HTTP 2.x will maybe make it smoother but will likely not replace it completely).

If your project is before all a frontend project you need to go on js side but if your project is simple and more centered on the data or the server side we can probably find a compromise.

This was the origin of “Oh My js!” which is a small library I created to integrate the pipeline I often use for frontend development with Maven and the Java stack I use (TomEE if you doubt of it ;)).

First of all what needs do I want to cover and which ones I’ll ignore:

  • dependency management: ignored. I only want to handle runtime js dependencies and they are not that numerous in general so it can be done manually or worse case using webjars and a small groovy script for the optimization – will not be part of this post but can be another one if needed
  • build: yes and no. There are multiple parts of a build in javascript: the “big final aggregation” which aims to put all resources we can in a single file to make client loading faster and (optional) each module transpilation/rendering/compilation/… This is this last part we will target
  • test: java has a good tooling to do it but see next note for a more nuanced answer
  • packaging: not sure javascript has a real packaging model yet but java has so all is fine and secured
  • deployment: I build a war so maven/gradle are perfect

Of course I listed far more that what this post will cover but it was to show that the “blocking” part for a java developer is finally small enough to get some work to fill the gap.

Side note: frontend-maven-plugin is a great tool bringing to maven nodejs tooling (npm, bower, gulp, karma…). This however still needs to know these tools and just provide a “main-build” friendly solution so the initial cost can be important but it can worth it if you will need a lot of javascript.

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CDI: replace the configuration by a register pattern

CDI doesn’t really have a configuration file. Of course the beans.xml is used to activate few features like interceptors but you can’t register a bean in it, can’t add a qualifier on a bean etc…

When it comes to writing a CDI library the question of the configuration hits you pretty quickly. Let see how to solve it with a not very complicated pattern making users life really nicer.

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The Promise of CompletableFuture? JAX-RS2 example!

CompletableFuture API introduced in Java 8 is different from previous Future in the way it is composable and usable as a promise. Let’s see how to integrate it with JAX-RS 2.

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Add missing functions to HtmlUnit: Vue.js case

Depending the application you work on HtmlUnit can miss few functions. If you open the javascript engine you will quickly see it is quite complex to extend from your code and can be annoying when sometimes it just misses few methods!

Let see with the case of Vue.js how to fix it very easily.

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Chunking and global report using JTA

If you have a batch processing records in chunks you probably want to keep track of what succeeds and fails. The issue is the commit is often done after your business code is executed which means you kind of loose track of what happens.

To solve it you can use TransactionSynchronizationRegistry and Synchronizations.

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Java 8 streams and JTA chunking?

Java 8 streams are very expressive – even if RxJava is even more 😉 – but sometimes EE integration is not that advanced. In case of a batch import of data it would be handy to use Stream API since we iterate over data to persist them but how to ensure we can use chunking – ie get a commit interval to not commit for each record?

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