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Automated Tests for Asynchronous Processes

It’s been a while since I’ve worked on a server-side application that had asynchronous behaviour that wasn’t already an event-driven system. Asynchronous behaviour is always an interesting challenge to design and test. In general, asynchronous behaviour should not be hard to unit test – after all, the behaviour of an action shouldn’t necessarily be coupled temporally (see forms of coupling). ...

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Important Production bugs and fixes for Storm and Kafka integration


I will describe here a few details for Storm and Kafka integration modules, a few important bugs that you should be aware and how to overcome some of them (especially for production installations). I am heavily using Apache Storm in production installations with Kafka as my main input source (Spout). Storm integration modules with Kafka and versions: Storm 0.x supports ...

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Database Initialization with play and Scala

Once starting your play prototype application one of the priorities is to initialize your database and also manage the database schema changes. Play provides us with evolutions. By utilizing evolutions we are able to create our database and to manage any futures changes to the schema. To get started we need  to add the jdbc dependency and the evolutions dependency. libraryDependencies ...

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Your first Web application with Play and Scala

Today we are going to develop a simple play application using Scala. To do so we must have sbt installed to our system. Once installed we issue the command sbt new playframework/play-scala-seed.g8 Then we are presented with an interactive terminal in order to pass valuable information. name [play-scala-seed]: PlayStarter organization [com.example]: com.gkatzioura scala_version [2.11.8]: scalatestplusplay_version [2.0.0]: play_version [2.5.13]: Then let ...

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Distributed Cache – Overview

What’s a distributed cache? A solution that is “deployed” in an application (typically a web application) and that makes sure data is loaded from memory, rather than from disk (which is much slower), in order to improve performance and response time. That looks easy if the cache is to be used on a single machine – you just load your ...

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MySQL Partition Pruning

Recently, we learned an expensive lesson about MySQL partition pruning. There, it is better to share it here so that others will not repeat our mistake. Background In our system, there is a big stats table that does not have primary key and indexes. This table is partitioned, but the lack of indexes often causes the full partition or even ...

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New Webinar: How to Avoid the Hidden Costs of Continuous Delivery

The time has come to solve the missing link of the CI/CD toolchain With constant change, comes constant risk. The silent killer of CI/CD initiatives is also its biggest advantage, a side effect of moving too fast when a major component of the same process that pushes releases forward remains outdated and left behind. A common misconception is that Continuous ...

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[MEGA DEAL] The 2017 Complete Java Bundle (95% off)

Embark On Your Coding Odyssey with A Deep Dive (58 Hours!) Into the Most Commonly Used Programming Language Hey fellow geeks, This week, on our JCG Deals store, we have an extreme offer. We are offering The 2017 Complete Java Bundle for only $49 instead of the original price of $1,273, yeap that is a massive 96% off. Use Practical ...

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