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Some more unit test tips

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In my previous post I showed some tips on unit testing JavaBeans. In this blog entry I will give two more tips on unit testing some fairly common Java code, namely utility classes and Log4J logging statements. Testing Utility classes If your utility classes follow the same basic design as the ones I tend to write, they consist of a ...

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2 Ways of Passing Properties / Parameters in Java EE 7 Batch

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When it comes to the Java EE 7 Batch Processing facility, there are 2 ways in passing properties / parameters to the chunks and batchlets. This quick guide shows you the 2 ways, which could be use very frequently when developing batch processing the Java EE 7 way. 1. Pre-Defined Properties / Parameters Before Runtime Pre-Defined properties are properties (name ...

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Using rlimit (And Why You Should)

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I’ve been going through some old notes and came across a reminder of setrlimit(2). This is a C system call that allows an application to specify resource limitations on a number of important parameters:               RLIMIT_AS – The maximum size of the process’s virtual memory (address space) in bytes. RLIMIT_CORE – Maximum size of ...

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Customizing HttpMessageConverters with Spring Boot and Spring MVC

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Exposing a REST based endpoint for a Spring Boot application or for that matter a straight Spring MVC application is straightforward, the following is a controller exposing an endpoint to create an entity based on the content POST’ed to it:                 @RestController @RequestMapping("/rest/hotels") public class RestHotelController { .... @RequestMapping(method=RequestMethod.POST) public Hotel create(@RequestBody @Valid ...

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Using Infinispan as a persistency solution

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Cross-posted from https://vaadin.com/blog/-/blogs/using-infinispan-as-a-persistency-solution. Thanks Fredrik and Matti for your permission! Various RDBMSs are the de-facto standard for persistency. Using them is such a safe bet by architects that I dare say they are used in too many places nowadays. To fight against this, I have recently been exploring with alternative persistency options, like graph databases. This time I played with Infinispan. ...

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Using Gradle to Build & Apply AST Transformations

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Recently, I wanted to both build and apply local ast transformations in a Gradle project. While I could find several examples of how to write transformations, I couldn’t find a complete example showing the full build process. A transformation has to be compiled separately and then put on the classpath, so its source can’t simply sit in the rest of ...

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An Inconvenient Latency

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Overview Vendors typically publish numbers they are happy with, and avoid telling you about a product’s weaknesses.  However, behind the numbers is a dirty secret if you know where to look. Why don’t we use GPUs for everything? Finding problems which naturally scale to thousands of data points/tasks is easy for some problems, and very hard for others.   GPUs ...

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R: Calculating rolling or moving averages

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I’ve been playing around with some time series data in R and since there’s a bit of variation between consecutive points I wanted to smooth the data out by calculating the moving average. I struggled to find an in built function to do this but came across Didier Ruedin’s blog post which described the following function to do the job: ...

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Load Balance WebSockets using Apache HTTPD

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JBoss EAP 6.3 provides a technology preview of WebSocket and WildFly have supported them as part of Java EE 7 compliance. github.com/javaee-samples/javaee7-samples/tree/master/websocket provide tons of Java EE 7 samples that run on WildFly. If you are interested in similar functionality on JBoss EAP 6.3 then github.com/jboss-developer/jboss-eap-quickstarts/tree/6.4.x-develop/websocket-hello is a quickstart. In addition, there are a few more samples at github.com/arun-gupta/jboss-samples/tree/master/eap63. One of the common questions ...

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