Lessons learned: Spring Data Postgres application configuration

Scenario: During development of a Spring Boot application, with a PostgreSQL backend, we randomly observe errors such as: hikaripool-1 - connection is not available, request timed out after 30000ms   FATAL: remaining connection slots are reserved for non-replication superuser connections   Solution: There are a few checks to perform: Ensure that you use the correct … Continue reading Lessons learned: Spring Data Postgres application configuration

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Reactive Spring: Combining Server-Side Events with Redis PubSub for real-time push events

A simple example of using Redis PubSub and Spring Reactive Server Side Events for real-time push events to the browser Spring Boot v2.0.3.RELEASE Coding using reactive functional style (as opposed to annotation-based) Spring Initializr Dependencies: “Reactive Web” Redis Driver Used: Jedis Language: Kotlin Scenario and design choices The scenario described in this article is depicted below: … Continue reading Reactive Spring: Combining Server-Side Events with Redis PubSub for real-time push events

Reactive Spring: Webflux Multipart File Upload

A clear, simple example of multipart file upload using Reactive Spring Spring Boot v2.0.3.RELEASE Coding using reactive functional style (as opposed to annotation-based) Spring Initializr Dependencies: "Reactive Web" Language: Kotlin Notes follow after the code: https://gist.github.com/dvas0004/fdb63086cd77869066e83a1ca25757d9 Notes: Spring Webflux makes it extremely easy to build reactive web services - but it takes a while to … Continue reading Reactive Spring: Webflux Multipart File Upload

Drill Down into Spring Boot Actuator metrics

We've only seen this very useful feature documented in the official Spring Actuator API Documentation, so maybe not many are aware that you actually have some control over what the Spring Actuator metrics return to your requesting client. The Spring Actuator API allows you to expose several useful metrics that you can use to monitor … Continue reading Drill Down into Spring Boot Actuator metrics

Google Yolo and Spring Boot 2.0 Authentication

Back in 2016, Google announced the "Open Yolo" project: You Only Login Once. It originally seemed to be an Android library but during Google's last Dev Summit in October 2017, Google released "One-tap Sign-ups On Websites and API Integrations" which brings Google Yolo to your website via JavaScript goodness. There's a very easy guide that … Continue reading Google Yolo and Spring Boot 2.0 Authentication

Developing Alexa Skills

In this article we'll explore how to add some custom skills to your Alexa powered device. The material in this blog post was tested on an Echo Dot - however Amazon recently enabled Alexa on most Android powered smartphones so the barrier for entry to developing these skills has been lowered significantly. I actually ended … Continue reading Developing Alexa Skills

Analyzing credit card transactions using machine learning techniques – 3

Introduction In a previous article, we explored how PCA can be used to plot credit card transactions into a 2D space, and we proceeded to visually analyse the results. In this article, we take this process one step further and use hierarchical clustering to automate parts of our analysis, making it even easier for our … Continue reading Analyzing credit card transactions using machine learning techniques – 3