In some of my recent work I got the request to produce a custom Reason Phrase in the  HTTP status response delivered to one of our REST API consuming clients when an error occurs. In this post I will demonstrate how you can achieve that with Jersey.

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Introduction

An incremental software development process requires an incremental database migration strategy.

I remember working on an enterprise application where the hibernate.hbm2ddl.auto was the default data migration tool.

Updating the production environment required intensive preparation and the migration scripts were only created on-the-spot. An unforeseen error could have led production data corruption.

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This post covers some basics of JVM memory structure and quickly peeks into PermGen to find out where it has disappeared since advent of Java SE 8

Bare Basics

The JVM is just another process running on your system and the magic begins with the java command. Like any OS process, it needs memory for its run time operations. Remember – the JVM itself is a software abstraction of a hardware on top of which Java programs run and boast of OS independence and WORA (write once run anywhere)

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I once visited a team that had fifteen layers in their code. That is: If you wanted to display some data in the database in a web page, that data passed through 15 classes in the application. What did these layers do? Oh, nothing much. They just copied data from one object to the next. Or sometimes the “access object layer” would perform a check that objects were valid. Or perhaps the check would be done in the “boundary object layer”. It varied, depending on which part of the application you looked.

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Java 8 comes with a new Optional type, similar to what is available in other languages. This post will go over how this new type is meant to be used, namely what is it’s main use case.

What is the Optional type?

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