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A beginner’s guide to java time zone handling

Basic time notions

Most web applications have to support different time-zones and properly handling time-zones is no way easy. To make matters worse, you have to make sure that timestamps are consistent across various programming languages (e.g. JavaScript on the front-end, Java in the middleware and MongoDB as the data repository). This post aims to explain the basic notions of absolute and relative time. Continue reading

Gzip Jersey

How to compress responses in Java REST API with GZip and Jersey

There may be cases when your REST api provides responses that are very long, and we all know how important transfer speed and bandwidth still are on mobile devices/networks. I think this is the first performance optimization point one needs to address, when developing REST apis that support mobile apps. Guess what? Because responses are text, we can compress them. And with today’s power of smartphones and tablets uncompressing them on the client side should not be a big deal… So in this post I will present how you can SELECTIVELY compress your REST API responses, if you’ve built it in Java with Jersey, which is  the JAX-RS Reference Implementation (and more)…  Continue reading

C#

C# Tricks: Slimming down your controllers

This blog post is dedicated to my colleague Seminda who has been experimenting with how to create simple and powerful web applications. Thank you for showing me your ideas and discussing improvements with me, Seminda.

I find many C# applications have much unnecessary code. This is especially true as the weight of the business logic of many applications are shifting from the backend to JavaScript code in the web pages. When the job of your application is to provide data to a front-end, it’s important to keep it slim.

In this article, I set out to simplify a standard MVC 4 API controller by generalizing the functionality, centralizing exception handling and adding extension methods to the DB set that is used to fetch my data. Continue reading

Java EE compatible

How to build and clear a reference data cache with singleton EJBs, Ehcache and MBeans

In this post I will present how to build a simple reference data cache in Java EE, using singleton EJBs and Ehcache. The cache will reset itself after a given period of time, and can be cleared “manually” by calling a REST endpoint or a MBean method. This post actually builds on a previous post How to build and clear a reference data cache with singleton EJBs and MBeans; the only difference is that instead of the storing of the data in a ConcurrentHashMap<String, Object> I will be using an Ehcache cache, and the cache is able to renew itself by Ehcache means. Continue reading

GraphDatabase_PropertyGraph

Solving ORM – Keep the O, Drop the R, no need for the M

ORM has a simple, production-ready solution hiding in plain sight in the Java world. Let’s go through it in this post, alongside with the following topics:

  • ORM / Hibernate in 2014 – the word on the street
  • ORM is still the Vietnam of Computer Science
  • ORM has 2 main goals only
  • When does ORM make sense?
  • A simple solution for the ORM problem
  • A production-ready ORM Java-based alternative

Continue reading

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Java WebSockets (JSR-356) on Jetty 9.1

Jetty 9.1 is finally released, bringing Java WebSockets (JSR-356) to non-EE environments. It’s awesome news and today’s post will be about using this great new API along with Spring Framework.

JSR-356 defines concise, annotation-based model to allow modern Java web applications easily create bidirectional communication channels using WebSockets API. It covers not only server-side, but client-side as well, making this API really simple to use everywhere. Continue reading

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MongoDB Incremental Migration Scripts

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. Continue reading

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JVM PermGen – where art thou?

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) Continue reading