Open Tabs: Resources for Web Developers, How to write perfect blog posts, Argus

Resources for Web Developers Freepik is a search engine for finding free vector graphics, PSDs, icons and and photos. If you have to quickly create a landing page for your AppStore product, you can use the free service Landing Harbor. Searching for a tool for your freelancer job? Take a look at The Freelance Stack. Need a new Bootstrap-based theme? Bootstrap Zero should give you a good start. How to write better blog posts You have no idea Read more…

Migrating InfluxDB from 0.9.6 to 0.10.0 GA

You may have already heard that InfluxDB 0.10 GA has been published a few days ago. In my case the most interesting improvement are the much higher compression rates: At the moment my co-workers of NeosIT and I are collecting performance data from four internal virtual machines. Have been running the collectd daemon on the VMs for about a month, the size of InfluxDB’s data directory increased by 3.5 GByte with default retention policy. Testing Read more…

Executing Liquibase database migrations from command line and as a shared Maven JAR

I am currently working on the migration of our time tracking system from Microsoft SQL Server/.NET to Java. Most of the logic resides in Stored Procedures and Stored Functions inside the database schema. Because of some reasons (testability, maintainability, migration from MSSQL to PostgreSQL in a far future) the whole logic must be converted to Java. As the system has a high criticality all of the end user applications must be running parallel. There are Read more…

Open Tabs: Awesome CV, uxdesign.cc & Mobile Patterns, re:Work, d3.compose, cloudcraft.co, SqlPad

In the last week the following links stayed longer open in my browser tabs: Awesome CV If you are searching for a LaTeX template for your resume you should definitely take a look at Awesome CV. I will probably use the template in one of my projects. uxdesign.cc and Mobile Patterns As I already mentioned from time to time I am a lousy user interface designer. Nevertheless I am interested in UI and UX. uxdesign.cc Read more…

Project idea: Nostradamus AKA prophetr – a social forecasting network for experts

From time to time some programming ideas come to my mind which I can not forget. I had often started a new project but due to my limited amount of free time it is hard to finish all of them. In the next blog posts I will describe my ideas with some technical and environmental background. If you are interested in getting more information, buying the idea/source code or just motivate me, just drop me Read more…

ExceptionHandler of @ControllerAdvice is not executed

It happened again: after writing about some issues caused by different JVM class-loader order a similar problem occured on Friday. One of my collagues (Dev-A) asked me to look into a problem the team had. Because of unknown reasons the Spring Boot based application did not return a serialized JSON error object after a @Valid annotated controller method parameter had been validated. An @ControllerAdvice annotated class transformed any validation error into a new exception. This has been done Read more…

How to fix NoSuchMethodError or NoSuchMethodException

Yesterday my team had the situation that a deployment failed with a NoSuchMethodError, specifically the method com/google/common/collect/ImmutableList.copyOf could not be found while querying the Confluence REST API. NoSuchMethodEror and NoSuchMethodException occur of obvious reasons: a method should be called during runtime but the providing class does not contain the method. NoSuchMethodExceptions is thrown when the JVM tries to make a call to a method through Java Reflection API. NoSuchMethodError is thrown when the compiled Java code directly calls the method Read more…

Collecting and visualizing metrics with statsd, InfluxDB and Grafana on Fedora 22

My employer NeosIT offers a web based SMS notifiyng solution for organizations with security roles named ZABOS. In the last months we extended the ZABOS application to support digital alerting through POCSAG. After some problems with a third party component we implemented the ability to collect all POCSAG telegrams delivered in the near circumcircle and to notify the authorized recipients by SMS. Most of the incoming telegrams are discarded because they are not assigned in Read more…

Slow RAID performance with our new Linux storage

During the last months we periodically experienced performance problems with our storage system. Investigating the cause for the slow performance was problematic as we did not have direct shell access and could only rely on crippled information from the web GUI. Yesterday my collagues migrated the storage system from the proprietary operating system solution to Fedora 22. After some problems with LVM and directory permissions for Samba, the storage went back online today in the Read more…