Heterogeneous microservices Microservices architecture is increasingly popular nowadays. One of the promises is flexibility and easier working in larger organizations by reducing the amount of communication and coordination between teams. The thinking is, teams have their own service(s) and don’t depend on other teams, meaning they can work independently, thereby reducing coordination efforts. Especially with […]
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 […]
Machine Learning: Predicting house prices
Recently I have followed an online course on machine learning to understand the current hype better. As with any subject though, only practice makes perfect, so i was looking to apply this new knowledge. While looking to sell my house I found that would be a nice opportunity: Check if the prices a real estate […]
Simulating an Elasticsearch Ingest Node pipeline
Indexing document into your cluster can be done in a couple of ways: using Logstash to read your source and send documents to your cluster; using Filebeat to read a log file, send documents to Kafka, let Logstash connect to Kafka and transform the log event and then send those documents to your cluster; using […]
Public Elasticsearch clusters are being held ransom
Last week several news sites and researchers reported that Elasticsearch clusters that are connected to the internet without proper security are being held ransom. You can use shodan.io to search for Elasticsearch clusters: https://www.shodan.io/search?query=port%3A9200+json&language=en. The first hit is actually a cluster that is ‘infected’: There are some secured clusters as well: But the default ‘root’ account with […]
Handling a massive amount of product variations with Elasticsearch
In this blog we will review different techniques for modelling data structures in Elasticsearch. A project case is used to describe our approach on handling a small sized product data set with a large sized related product variations data set. Furthermore we will show how certain modelling decisions resulted in a 1000 factor query performance gain! […]
Service Discovery using Consul & Spring Cloud
Introduction In one of our customer projects we are heavily using Spring Boot in combination with other Spring projects for our microservices. One of the more complex parts of microservices, especially when you are using them as fine-grained as meant to be, will be the fact that you need to setup and maintain the connections […]
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 […]
Measure the Adequacy of Android Unit Tests with Mutation Testing
Unit tests are an essential tool in a trustworthy test suite for an Android application or any other software system for that matter. But unit tests themselves doesn’t guarantee that the right features or requirements are tested, even if you did a thorough effort to cover as much code as possible in your entire code […]
Collecting data from a private LoRaWAN sensor network into Elastic
Introduction to LoRaWAN and ELK Why LoRaWAN, and what makes it different from other types of low power consumption, high range wireless protocols like ZigBee, Z-Wave, etc … ? LoRa is a wireless modulation for long-range, low-power, low-data-rate applications developed by Semtech. The main features of this technology are the big amount of devices that […]