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RESTful services with HATEOAS: REST APIs and Hypermedia on JVM

java-interview-questions-answers

1. Introduction So far we have spent a fair amount of time talking about the role of the hypermedia and HATEOAS in the RESTful web services and APIs, glancing over different specifications and usability aspects. It sounded like supporting hypermedia and HATEOAS is not that difficult, just pick you favorites and you are good to go! As you may guess, ...

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JVM Garbage Collection and Optimizations

Overview When troubleshooting systems for performance-related issues, memory optimizations are a place that needs a deep analysis of what each system stores in the memory, how long those are stored, and access patterns. This post is to keep a note on the background information and valuable points to note in such an effort, specific to Java-based implementations as a deep ...

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Apache Derby Database JVM Security Policy

java-interview-questions-answers

Abstract I have already posted a number of blogs about Derby: Derby Database BackupMultiple Derby Network Servers on the same HostApache Derby Database Users and PermissionsIntegration Testing with Maven and an In-Memory Derby Database This wasn’t intended to be a series. But over the years I’ve been using Derby more and more. I started using Derby as my database of ...

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How to process images and videos within Java JVM

Processing of images – let alone videos – within the Java JVM has always been a challenging task. ImageIO classes have come a long way since JDK7 – together with the usual SDK bugs – not always giving you what you expect (bad image quality, not always supporting all types of JPEG standards, …). At the end of the line you are ...

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JAR File Handles: Clean Up After Your Mess!

In Ultra ESB we use a special hot-swap classloader that allows us to reload Java classes on demand. This allows us to literally hot-swap our deployment units – load, unload, reload with updated classes, and phase-out gracefully – without restarting the JVM. Windows: supporting the forbidden land In Ultra ESB Legacy the loader was working fine on Windows, but on ...

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OutOfMemoryError related JVM arguments

JVM has provided helpful arguments to deal with OutOfMemoryError. In this article, we would like to highlight those JVM arguments. It might come handy for you when you are troubleshooting OutOfMemoryError. Those JVM arguments are: -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath-XX:OnOutOfMemoryError-XX:+ExitOnOutOfMemoryError-XX:+CrashOnOutOfMemoryError Let’s discuss these JVM arguments in detail in this article. (1). XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath Heap dump is basically a snapshot of memory. It contains details ...

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Is your JVM leaking file descriptors – like mine?

Foreword: The two issues described here, were discovered and fixed more than a year ago. This article only serves as historical proof, and a beginners’ guide on tackling file descriptor leaks in Java. In Ultra ESB we use an in-memory RAM disk file cache for fast and garbage-free payload handling. Some time back, we faced an issue on our shared ...

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JVM with no garbage collection

JVM community keeps on adding new GC and recently new one was added and it is called  Epsilon and is very special one. Epsilon only allocates memory but will not reclaim any memory. It might look like what is use of GC that does not perform any garbage collection. This type of Garbage Collector has special use and we will look ...

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Top 9 Free Java Process Monitoring Tools & How to Choose One

So your Java code runs. Perhaps it even runs on a production server. After you pat yourself on the shoulder on a job well done, we’ve got good news and annoying news. The annoying news is that now, the debugging starts. Debugging and application performance monitoring that is. This means looking beyond the code written and into the internal workings ...

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