Bozho's tech blog

Yesterday Dyn, a DNS-provider, went down after a massive DDoS. That led to many popular websites being inaccessible, including twitter, LinkedIn, eBay and others. The internet seemed to be “crawling on its knees”. We’ll probably read an interesting post-mortem from Dyn, but why did that happen? First, DDoS capacity is increasing, using insecure and infected […]

When we are building web applications these days, it is considered a best practice to expose all our functionality as a RESTful API and then consume it ourselves. This usually goes with a rich front-end using heavy javascript, e.g. Angular/Ember/Backbone/React. But a heavy front-end doesn’t seem like a good default – applications that require the […]

You’ve probably heard about “the right to be forgotten” according to which Google has to delete search results about you, if you ask them to. According to a new General Data Protection Regulation of the EU, the right to be forgotten means that a data subject (user) can request the deletion of his data from […]

If you need to have automatic auditing of all database operations and you are using Hibernate…you should use Envers or spring data jpa auditing. But if for some reasons you can’t use Envers, you can achieve something similar with hibernate event listeners and spring transaction synchronization. First, start with the event listener. You should capture […]

Hibernate offers event listeners as part of its SPI. You can hook your listeners to a number of events, including pre-insert, post-insert, pre-delete, flush, etc. But sometimes in these listeners you want to use spring dependencies. I’ve written previously on how to do that, but hibernate has been upgraded and now there’s a better way […]

It sounds like something you’d never need, but sometimes, when you distribute end-user software, you may need to install a java program as a Windows service. I had to do it because I developed a tool for civil servants to automatically convert and push their Excel files to the opendata portal of my country. The […]

There are many ways to work with git. The workflows vary depending on the size of the team, organization, and on the way of working – is it distributed, is it sprint-based, is it a company, or an open-source project, where a maintainer approves pull requests. You can use vanilla-git, you can use GitHub, BitBucket, […]

I’ve been spring-cleaning some devices and the obviousness of the advice in the title seems questionable. I found tons of unused temp files which applications (android apps, desktop applications and even server application deployments) haven’t cleaned. This is taking up space and it means more manual maintenance. For server-side applications the impact is probably smaller, […]

In practically every project you’ve used a “dirty hack”. setAccessbile(true), sun.misc.Unsafe, changing a final value with reflection, copy-pasting a class from a library to change just one line of wrong code. Even if you haven’t directly, a library that you are using most certainly contains some of these. Whenever we do something like that, we […]

Inserts, updates and deletes. Every framework tutorial starts with these and they are seen as the most basic functionality that just works. But what if two concurrent requests try to modify the same data? Or try to insert the same data that should be unique? Or the inserts and updates have side-effects that have to […]