As most of you will know, every now and then you can expect the question ‘Can you help fix something on this ancient project?’ According to the Universal Software Ageing table, that means anything from last month to much, much older. I got such a question recently, being in-between projects, and this project fell squarely into […]
Spring Data Native Queries and Projections in Kotlin
This blog describes the solution to mapping native queries to objects. This is useful because sometimes you want to use a feature of the underlying database implementation (such as PostgreSQL) that is not part of the JPQL standard. By the end of this blog you should be able to confidently use native queries and use […]
Refactoring from Elasticsearch version 1 with Java Transport client to version 6 with High Level REST client
Every long running project accrues technical debt. It may be that the requirements today have evolved in a different direction from what was foreseen when the project was designed, or it may be that difficult infrastructure tasks have been put off in favor of new functionality. From time to time, you need to refactor your […]
How to send your Spring Batch Job log messages to a separate file
In one of my current projects we’re developing a web application which also has a couple of dozen batch jobs that perform all sort of tasks at particular times. These jobs produce quite a bit of logging output when they’re run, which is important to see what has happened during a job exactly. What we […]
Writing less code
Have you had that feeling that you have to write too much code to build simple functionality? Some things just feel repetitive, they feel you should be not have to write them yourself, instead a framework should make your life easier. Recently I’ve been building a project in Java/Spring, and after some time I started wondering […]
Dealing with NodeNotAvailableExceptions in Elasticsearch
tl;dr Elasticsearch provides distributed search with minimal setup and configuration. Now the nice thing about it is that, most of the time, you don’t need to be particularly concerned about how it does what it does. You give it some parameters – “I want 3 nodes”, “I want 3 shards”, “I want every shard to […]
Bridging the Gap: An Interview with Chicago User Group Leaders
It’s no secret that Chicago is an incredible city with a vibrant history, passionate sports fans, and very cold weather. However, what many people are starting to realize is that Chicago is also an up-and-coming home for the Tech Industry: with companies like 1871 and WeWork serving as incubators for newly hatched start-ups, the space […]
Active cache eviction with Ehcache and Spring Framework
Caching is an essential to the majority of web applications. Let’s face it: most of the work done in an average web application (especially public ones) is repetitive, either the same user requesting the same information multiple times, or multiple users requesting the same information. The question is always: “How long do I cache”? We […]
ANWB Big data Proof of Concept
At the ANWB people are constantly trying to improve the services they provide. One of these services is to provide traffic information. In the Netherlands the National Data Warehouse for Traffic Information (NDW) provides an enormous database of both real-time and historic traffic data. This data comes from many different sources and is available as open […]
Integrating Flyway In A Spring Framework Application
This post is about how to integrate Flyway into a Spring/JPA application for database schema migration. To skip all the preambles and get straight to the instructions, jump to Project’s Dependencies Set-up Flyway is a database migration tool which helps do to databases, what tools like git/svn/mercurial does for source code…which is versioning. With Flyway you […]