Become high performing. By being happy.  

Paul Takken

The summer holidays are over. Fall is coming. Like the start of every new year, a good moment for new inspiration.

Recently, I went twice to the Boston area for a client of Xebia. I met there (I dislike the word “assessments"..) a number of experienced Scrum teams. They had an excellent understanding of Scrum, but were not able to convert this to an excellent performance. Actually, there were somewhat frustrated and their performance was slightly going down.

So, they were great teams, great team members, their agile processes were running smoothly, but still not a single winning team. Which left in my opinion only one option: a lack of Spirit.   Spirit is the fertilizer of Scrum and actually every framework, methodology and innovation.  But how to boost the spirit?
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Help! Too Many Incidents! - Capacity Assignment Policy In Agile Teams

Pieter Rijken

As an Agile coach, scrum master, product owner, or team member you probably have been in the situation before in which more work is thrown at the team than the team has capacity to resolve.

In case of work that is already known this basically is a scheduling problem of determining the optimal order that the team will complete the work so as to maximise the business value and outcome. This typically applies to the case that a team is working to build or extend a new product.

The other interesting case is e.g. operational teams that work on items that arrive in an ad hoc way. Examples include production incidents. Work arrives ad hoc and the product owner needs to allocate a certain capacity of the team to certain types of incidents. E.g. should the team work on database related issues, or on front-end related issues?

If the team has more than enough capacity the answer is easy: solve them all! This blog will show how to determine what capacity of the team is best allocated to what type of incident.

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Why even Spray-can is Way Too Slow (for my purposes)

Wilco Koorn

In a previous blog I discussed the speed of the Spray-can web-server and mentioned some measurements I did. My co-worker Age Mooij, committer on the Spray project, pointed me at 'weighttp' (see weighttp at github) a tool for benchmarking web servers. Cool! Of course I now had to do more experiments and so I did. I found out Spray-can is way too slow for my purposes and here's why.
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Performance testing with Selenium and JMeter

Mark Bakker

In this blog I will show a way to do performance testing with Selenium. The reason I use Selenium for performance testing is that some applications use proprietary protocols between the application layer in the browser and the server.

So just capturing the traffic between the server and replaying modified traffic is not that simple.

An example is testing GWT applications. In a previous blog I wrote why this is difficult.

To create a test script in Selenium the first thing I do is record a test with Selenium IDE
After recording a script I export the script to JUnit3 (Remote Control). This will generate a JUnit test script which can be run to test the application.

The next thing you need is a solution to run a lot of JUnit test cases at the same moment.

Here you see a visual representation of the whole test chain.

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Design a large scale NoSQL/DataGrid application similar to Twitter.


Design a large scale NoSQL/DataGrid application similar to Twitter with Nati Shalom (Founder and Chief Technology Officer at GigaSpaces).  Read more

Performance on Amazon AWS


The following story I find really interesting.
Bhaskar Sunkara, VP Product Experience at AppDynamics, presents "Performance on Amazon AWS".
Among other things, AppDynamics is known to be used by NetFlix to monitor thousands of JVMs on Amazon AWS.

The presentation tells you about how Netflix partnered with App Dynamics to monitor their systems in a (more than) dynamic cloud infrastructure by AWS.
A large part of the presentation explains about what the important design principles are to be aware of when developing for the cloud.

Main message: machines will come and go, systems will go down. Application availability is in the hands of the developer. Develop for availability.


Testing GWT applications for capacity and performance

Mark Bakker

In my current role as application performance specialist I see a lot of different frameworks that are used to develop applications faster, to make a more reactive frontend application or just a framework that is the latest and greatest from a development point of view.

One of these frameworks is Google Web Toolkit. Frameworks like this are a good thing for development… but for performance testing they might be a problem.

For performance testing the best practice is to use a proxy server recording all traffic between a browser and the application. In most cases this is just plain http with html or xml as a protocol. So it is easy to replay the recorded test and parameterize it with different values. Read more

The "Performance Series" Part 1. Test Driven Performance.

Wilco Koorn

A number of my colleagues and myself recently decided to share our knowledge regarding "performance" on this medium. You are now reading the first blog in a series in which I present a test-driven approach to ensuring proper performance when we deliver our project.

Test driven

First of all note that "test-driven" is (or should be ;-) common in the java coding world. It is, however, applied to the unit-test level only: one writes a unit test that shows a particular feature is not (properly) implemented yet. The test result is "red". Then one writes the code that "fixes" the test, so now the test succeeds and shows "green". Finally, one looks at the code and "refactors" the code to ensure aspects like maintainability and readability are met. This software development approach is known as "test driven development" and is sometimes also referred to as "red-green-refactor". Read more

3-2-1 Bang! Summary of first Software Architecture Pressure Cooker meetup

Gero Vermaas

Last Thursday the first Software Architecture Pressure Cooker meetup was held. The goal of these meetups is to exchange experiences on software architecture. This is done by working on a real life case using the following format:

  1. A specific challenging scenario is introduced in general terms
  2. An organization is invited to present a real life case that matches the scenario introduced, they act as product owner during the evening.
  3. In a couple of rounds the group brainstorms, breaks up in sub groups and works on solutions.
  4. All solutions are presented to the product owner
  5. Some heated discussions take place between the various subgroups where each group tries to convince the other groups.

The scenario for this first meetup was "3-2-1 Bang!". Characteristics of this scenario are:
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Scala Lists: Watch your append and prepends

Jeroen van Erp

Today I came across a nice problem in a piece of code one of our colleagues sent around asking for improvements. The problem consists of grouping a large List of lines according to some characteristics. Once the List grew large, the function which took care of the grouping took over 2 minutes to group the dataset. Read more