All posts by Rene

iJUG-Magazin Java aktuell – Performance Tests of Microservices

Load and performance testing is not trivial. Load and performance testing microservices is even more challenging. Our article “Performance Tests of Microservices” in the iJUG-Magazin Java aktuell talks about approach and challenges when designing and executing performance test for microservices. So get yourself the Java Aktuell or, if you just want to check out the article, use this link to the PDF and enjoy. The article is in German.

Performancetests von Microservices

Eine Softwarearchitektur, die aus kleinen und unabhängigen Teilen zusammengesetzt ist, ist einfacher zu erstellen und zu warten. Microservices sind dadurch zum dominierenden Thema in der modernen Softwareentwicklung geworden. Während die Komplexität auf der Entwicklungsseite sinkt, steigt sie in Bezug auf die Themen Architektur, Performance und Zuverlässigkeit. Dieser Artikel diskutiert die Anforderungen an die Performance und die Planung von Performancetests von Microservices.

Comments are very welcome.

2020 – One Year, One Picture

One Picture Says It All

If we can only use one picture to symbolize 2020, this might just be it. Working from home and video conferences are now the new normal.

Happy Holidays, Merry Christmas, and a Happy and Healthy 2021, because we all need that.

iJUG-Magazin Java aktuell – High Performance Java

Java Aktuell Cover Issue 2/2020
Java aktuell 2/2020

After our presentation at the JUG Saxony Day in 2019, we have been asked to turn the talk into an article for the iJUG-Magazin Java aktuell. The February 2020 issue just got published and features this article. So get yourself the latest Java Aktuell or, if you just want to check out the article, use this link to the PDF and enjoy. The article is in German.

High Performance Java – Hinter den Kulissen von Java

Die Zeiten, in denen Java der langsame Bytecode-Interpreter war, sind lange vorbei. Die JVM nutzt viele Tricks, um Code effizient auszuführen, und transformiert und optimiert Java-Code auf die ausführende Hardware. Mit etwas Wissen über diese Prozesse kann man vermeiden, dass man gegen die JVM arbeitet, und gleichzeitig mehr Geschwindigkeit erreichen. Selbst wenn man nicht die letzte Mikrosekunde jagt, ist es interessant zu sehen, welche Techniken die JVM einsetzt, um die Ausführungsumgebung besser zu verstehen.

Comments are very welcome.

Xceptance LoadTest Goes Open Source

We have often been asked why XLT (Xceptance LoadTest) is free but not open source. Now, after considering our customers’ business needs and the advantages of using open source as opposed to free software, Xceptance has decided to open source XLT under the Apache License 2.0.

Within the next 30 days, we will restructure the XLT code base and move subprojects into independent open repositories. We will continue to expand and improve the documentation. All code will be published on GitHub.

Xceptance will continue to maintain and extend XLT as before. Releases will be built and published by Xceptance on a regular schedule. Libraries will be published to Maven Central as part of the open-sourcing process. The latest releases will be available from the XLT GitHub repository as well. Of course, the GitHub defect tracker will start to be your source for feature development and defect fixes.

If you are interested in training, projects, or support for XLT and load testing in general, we of course also offer those services, and will expand this offering further in upcoming months.

By open sourcing, we are opening a new chapter for XLT and we invite everyone to join us. More to come!

BOM – Byte Order Mark

Because we encountered another hidden encoding issue as part of test data, here are some information about BOM and why this might be interesting in general for everyone working with a computer beyond Excel and Word.

Before you educate yourself, here is the tool to own to see such a problem easily. Most of all editors hide that information and so you might scratch your head why some data is failing with strange error messages. Get xxd and you will see with other eyes:

xxd /tmp/2018-01.csv 
0000000: efbb bf23 4375 7374 6f6d 6572 204e 756d  ...#Customer Num
0000010: 6265 722c 5265 6164 204f 6e2c 506f 7765  ber,Read On,Powe
0000020: 7220 4d65 7465 7220 5265 6164 696e 670d  r Meter Reading.
0000030: 0a30 3030 312c 3230 3138 2d30 352d 3032  .0001,2018-05-02
0000040: 2c35 3030 0d0a                           ,500..

The first marked bytes are the magic and now head over to the Wikipedia to read more about BOM:

Java Training Sessions

Today we are going to publish four of our Java training sessions so you can use the material and benefit from it.

Let’s get started with four direct links to extensive material that might help you to understand Java or code quality better or just help you to reflect on topics you already know.

  • The Java Memory Model: Why you have to know the JMM to understand Java and write stable, correct, and fast code.
  • Java Memory Management: Know more about the size of objects and how Java does garbage collection.
  • High Performance Java: All about the smart Java internals that turn your code into fast code and how you can leverage that knowledge.
  • High Quality Code: The anatomy of high quality code that supports longevity, cross-team usage, and correctness. This is not just about Java, this is about good code in general.

Show a little patience when loading the training, these are all large reveal.js based slide sets. Use the arrow keys or space to navigate. Because the slide sets are designed to be interactive sessions, in many cases, not the entire slide context is revealed at once but block by block.

We publish these training sessions because they are also based on openly shared material, it greatly helped us to advance and understand, as well of course advertise a little what Xceptance might be able to do for you.

We will release more of our material in the next weeks and month, so everybody can browse and learn. This won’t be limited to Java and also cover material about approaching load testing, how to come up with test cases, and more about the modern web and its quality and performance challenges. Of course there will be more Java material too. You can get a glimpse of it when you just follow this link and page through the slides: The Infinite Java Training. Please remember, not all material is complete yet.

If you like the material and you need an audio track aka a real presentation, please talk to us. If you see other training needs in the area of quality assurance, testing, and Java, please contact to us.

More to come.

Thuringia’s Open-Source Prize for XLT

Wolfgang Tiefensee, Thuringia’s Secretary of Commerce, in conjunction with the board of directors of the IT industry network ITNet Thuringia, awarded the first Thueringen Open-Source Prize to three companies, all of them software companies based in Jena: TRITUM, Xceptance and GraphDefined.

Open Source Prize Title Picture Second Place

It is an honor for Xceptance to be the second-place winner of this competition. This result clearly demonstrates that open source as a component of commercial products can be a clear competitive advantage. XLT incorporates a number of open-source projects, including Apache HttpClient, Jetty, HtmlUnit, JUnit, and the Apache Commons libraries. As part of developing XLT, Xceptance is involved in testing and providing feedback for these projects, thus giving back to the open-source community.

While XLT is itself not open source, Xceptance does provide the software free of charge and with virtually no usage restrictions, so for most applications there is no noticeable difference to open-source software.

Neodymium – An Open Source Framework for Web Testing

TL;DR: Neodymium is a Java-based test library for web automation that utilizes existing libraries (Selenide, WebDriver, Allure, JUnit, Maven) and concepts (localization, test multiplication, page objects) and adds missing components such as test data handling, starter templates, multi-device handling, and other small but useful everyday helpers.


As a company focused on quality assurance and testing, Xceptance always needs test automation software, especially end-to-end automation software. Several years ago we built a Firefox add-on that was designed to create and run browser automation. The tool was primarily used by people who didn’t necessarily have a strong background in software development. Today, the landscape is a bit different: Mozilla cut the cord on the APIs we were using and standard programming languages have largely taken over test automation because they are more flexible and less proprietary. These changes convinced us it was time to implement an idea we had already hatched, namely our own Open Source test automation project: Neodymium. It is written in and utilizes the Java platform, it is MIT licensed, and of course you will find it on GitHub:


There are many libraries out there to aid web automation in Java, so developers are faced with the task of choosing ones they like and somehow making them work together. On top of that, there are tasks that require some custom code to work properly. We identified the overall tooling problem mostly as a hurdle in getting started and setting up a project. Finally, there are always things missing such as test data handling, concurrency, and common patterns which you don’t want to have to develop yourself. We chose JUnit, Selenide, WebDriver, Maven, and Allure for the base tooling.

Selenide provides an easy-to-use API to control Selenium WebDriver. Allure offers good mechanics to generate useful reports based on the assertions and actions you perform throughout your test cases. Maven is used to set up the build and execution environment for our framework and all the test projects. We decided to use JUnit as the test runner since it is the de facto standard in the Java world, but we enhanced the capabilities of JUnit to do even more. At its heart, Neodymium is a JUnit runner that wraps default JUnit behavior and adds significant useful functionality to it.

Multiple Browsers

You want to be able to run the same tests for different resolutions and/or browsers to simulate the browsers most common among your users. Additionally, you need to be able to implement small differences within your test execution to address variants such as responsive designs or progressive web apps. So we added a way to run web browsers with different configurations and retrieve the current device type and resolution from within the test.

Neodymium provides a Java annotation that can be added to your test case, in order to run different browser setups. Neodymium is very flexible in configuring browsers, allowing you to fully leverage the Chrome device emulation offerings.

Test Data

Another common task is the execution of a test case with different data sets, such as testing address forms with all the relevant variations. The basic idea is to have test data and data sets in structured files next to your code, preferably as JSON, XML, property style, or simply CSV. Hence, we introduced an easy-to-use API to access the current data set and retrieve basic types from it. Furthermore, you can configure specific scenarios running only a subset or even no data set at all by adding proper annotations. To complete the picture, Neodymium supports test data on a global and package-level scope.


Another recurring topic in modern software projects is localization. Most of the web sites that are in need of test automation also support several locales. We decided to provide an out-of-the-box solution.

Neodymium’s localization feature makes use of a central translation file written in YAML format. YAML helps to structure the translations. Additionally, we implemented a simple way to override specific translations for different locales. The localized text can be easily retrieved using Neodymium API methods that are globally available.

Development Support

As it is essential to understand what your test is doing, we added a feature that enables you to slow down the test execution and highlight elements that match the current selector. Since you can chain selectors using Selenide, any chain of elements is also represented by the highlighting. With this feature activated, a developer can track down the cause of test failures much more easily. In addition, we provide information on how to set up logging in your project should you need that. Finally, we decided to use the Page Object pattern to organize the website-related code to reduce the maintenance effort and increase reusability.   


Allure is a widely used framework to generate reports. When using Neodymium with Selenide, your automation code also contributes report information. Your test classes and methods are listed as well as detailed Selenide automation commands. In case of errors, additional details such as screenshots and source code of the page in question are available. Neodymium also provides means to structure code blocks for reporting purposes.

Continuous Integration

Implementing principles of continuous integration will deliver more reliable software by increasing efficiency, and automation is nothing without a continuous integration environment.  Yet in almost every development cycle you will eventually end up needing varied settings due to differences in your setup, which can get complicated. Neodymium provides support for extra configuration files during development to override the standard production settings as needed. Furthermore, the framework supports overriding properties that change the configuration of your test execution by setting environment variables or simply passing Java arguments.

Because automation is supposed to run quickly, Neodymium provides support for parallel test execution and also demonstrates that setup as part of the sample test suite.

Documentation and Templates

Does Neodymium address some of your test automation challenges? Does it sound like a good entry point for your test automation?

Neodymium is hosted on GitHub (, where the accompanying project wiki ( provides extensive documentation to help you get started and answer your questions.

You might also want to take a look at the comprehensive example projects using Neodymium with Cucumber ( or plain Java ( We’ve even provided a template project ( to get you started automating in no time.


Neodymium is licensed under the MIT License.

Who Are We

We are Xceptance. A software testing company with strong commerce knowledge and projects with customers from all around the world. Besides Neodymium, we have developed Xceptance Load Test (XLT), a load and performance test tool that is available free of charge and features an extensive range of awesome features to make the tester’s and developer’s life easier.

If you are looking for test automation that also covers the performance side of life, take a look at XLT. You can write and run load tests with real browsers including access to data from the Web Performance Timing API. In case browsers are too heavy, XLT has other modes of load testing to offer as well.

We offer professional support for Neodymium as well as implementation and training services.

XLT 4.12.2 Release

Xceptance released version 4.12.2 of its load testing and test automation product Xceptance LoadTest. This is an improvement release. We recommend upgrading to this newest version.

Test Framework

  • Improvement: The result browser features a new tab that displays JSON responses in a tree-like view. The data can also be searched and filtered.
  • Improvement: The existing automatic request retry mechanism has been enhanced to retry failed requests in additional error situations such as connection resets. This should now behave similar to real browsers.
  • Improvement: When failed requests are retried, an event with diagnostic information is logged for each retry.
  • Improvement: The bundled Jetty library has been updated to the latest available version 9.4.14.

Load Testing

  • Improvement:  Our public AWS machine images now come with OpenJDK 11.

Make sure to read the full online release notes.

As always, this upgrade is free and don’t forget, XLT itself is free as well. You don’t have an excuse to skip performance testing or rely on lame simple test cases anymore.

XLT 4.12.1 Release

Xceptance has released version 4.12.1 of its load testing and test automation product Xceptance LoadTest.

Test Framework

  • Fix: Our timer recorder extensions for Chrome and Firefox did sometimes report invalid request entries that could not be processed by the report generator. This could happen for requests that did not complete.
  • Fix: If a test case deliberately caught an exception / assertion error and afterwards ran to completion successfully, it might nevertheless be marked as failed in the load test report.
  • Improvement: Selenium has been updated to the latest version 3.141.59 and HtmlUnitDriver to version 2.33.3.

Load Testing

  • Improvement: The new AWS data center in Stockholm, Sweden (eu-north-1) is fully supported by ec2_admin now.

Make sure to read the full online release notes.

As always, this upgrade is free and don’t forget, XLT itself is free as well. You don’t have an excuse to skip performance testing or rely on lame simple test cases anymore.