In a React world, everything is an event that anybody can grab and process according to whatever its responsibility is. The notion of event allows for very low contract coupling; it acts as a medium between classes. A message is similar, but with more coupling as it aggregates endpoints or endpoints addresses.
This model offers flexible design where events flow and are processed through the systems. But what happens when you have too many events to process?
Continue reading “Workload management strategies”
My mate Thomas Pierrain and I were lucky enough to have our topic selected for Devoxx FR 2014. The subject was the presentation of the sequencer and an iterative design exercise for a financial real-time pricing service.
Many thanks to our amazing audience that gave us interesting questions and good feedback. For those who may be interested, the talk can be seen on Parleys in the Devoxx FR channel.
My previous post, XP revival, dealt with the positive trend around XP as a project methodology. I explicitly stated that adding Craftsmanship practices on top of Scrum does not mean that you’re doing XP. In this post I am going to answer the explicit request to elaborate more on that topic. It is a well-known fact that Scrum prescribes no engineering practice, leaving teams choosing the ones they see fit. A strategy that led more often than not to what Martin Fowler coined as flaccidscrum, projects which velocity drops to a halt. This situation also contributed to the birth of the Software Craftsmanship movement, which aims at raising the bar for code engineering practices. It also stresses out that a coder must make those practices his own responsibility.
Continue reading “Scrum + Craftsmanship != XP”
There is an eXtreme Programming revival rising wave in the wake of the Software Craftsmanship tide. I do think this is great news, as coding practices and tools were put in a closet by most of the firms that went Agile the Scrum way. But, XP is not Scrum + Software Craftmanship, this simple arithmetic does not reflect the specific attributes of those ideas.
Continue reading “XP Revival”
In my previous post, I mentioned that I had actually 4 implementations proposal and I commented two of them, which were within the drafted requirements but had an issue with fairness: in both cases, one could bypass the thread pool queue altogether.
Let’s turn our attention to the other two, which are interesting because they share a common issue while having radically different approach.
C#, very short one
Java, long implementation
Clearly, the .Net version benefits from the TPL features. That being said, they are actually very close as they share the same algorithm: ordering is secured by creating a private queue, and non concurrency is ensured by making sure at most one task is enqueued or executing in the .net threadpool.
Contract is fulfilled, albeit with a steep price in terms of performance, or more precisely latency. As a task is actually dispatched only after the previous one have been executed, there is a minimum delay between two tasks. So, once again there is a fairness issue. It is obvious that non sequenced tasks would be executed faster than sequenced ones.
Continue reading “The Sequencer (part 2.2)”