Scala has very limited implementation of Enumeration. Enumerated objects can't extends other classes. Partial replacement for it is to use sealed classes. You can do pattern matching on them. When you ommit some possible value you will get compiler wa... Read more
During a last few evenings in my free time I've worked on mini-application called micro-burn. The idea of it appear from work with Agile Jira in our commercial project. This is a great tool for agile projects management. It has inline tasks edition, drag & drop board, reports and many more, but it also have a few drawbacks that turn down our team motivation.
From time to time our sprints scope is changing. It is not a big deal because we are trying to be agile :-) but Jira's burndowchart in this situation draw a peek. Because in fact that chart shows scope changes not a real burndown. It means, that chart cannot break down an x-axis if we really do more than we were planned – it always stop on at most zero.
Also for better progress monitoring we've started to split our user stories to technical tasks and estimating them. Original burndowchart doesn't show points from technical tasks. I can find motivation of this – user story almost finished isn't finished at all until user can use it. But in the other hand, if we know which tasks is problematic we can do some teamwork to move it on.
So I realize that it is a good opportunity to try some new approaches and tools.
I've started with lift framework. In the World of Single Page Applications, this framework has more than simple interface for serving REST services. It comes with awesome Comet support. Comet is a replacement for WebSockets that run on all browsers. It supports long polling and transparent fallback to short polling if limit of client connections exceed. In backend you can handle pushes in CometActor. For further reading take a look at Roundtrip promises
Lift-ng also provides factories for creating of Angular services. Services could respond with futures that are transformed to Angular promises in-fly. This is all what was need to serve sprint history:
And on the client side - use of service:
In my opinion this two frameworks gives a huge boost in developing of web applications. You have the power of strongly typing with Scala, you can design your domain on Actors and all of this with simplicity of node.js – lack of json trasforming boilerplate and dynamic application reload.
DDD + Event Sourcing
I've also tried a few fresh approaches to DDD. I've organize domain objects in actors. There are SprintActors with encapsulate sprint aggregate root. Task changes are stored as events which are computed as a difference between two boards states. When it should be provided a history of sprint, next board states are computed from initial state and sequence of events. So I realize that the best way to keep this kind of event sourcing approach tested is to make random tests. This is a test doing random changes at board, calculating events and checking if initial state + events is equals to previously created state:
Screenshot of first version:
If you want to look at this closer, check the source code or download ready to run fatjar on github.During a last few evenings in my free time I've worked on mini-application called micro-burn. The idea of it appear from work with Agile Jira in our commercial project. This is a great tool for agile projects management. It has inline tasks edition, drag & drop board, reports and many more, but it also have a few drawbacks that turn down our team motivation. Read more
BackgroundScala has nice static type checking engine but from time to time there are situations when we must downcast some general object. If this casting is not possible we expect that virtual machine will throw ClassCastExeption as fast as possible. ... Read more
Monad are containers with 'special powers', when it comes to applying function over its content.Validation special power is propagating Failure over validation process.If you are not familiar with scalaz.Validation I urge you to read this example,... Read more
Last time in our project we had to add progress bar for visualization of long time running process. Process was made of a few phases and we had to print in which phase we currently are. In first step we conclude that we need to create a class of Progre... Read more
Już w najbliższą sobotę – Scalar – bezpłatna konferencja dla wszystkich zainteresowanych Scalą. TouK ma przyjemność być jednym ze sponsorów wydarzenia. Podczas przerw będziemy rozglądać się za młodszym developerem Scali, więc jeśli jesteś zainteresowany pracą, wypatruj ludzi z TouK.
This Saturday – Scalar – a free conference for funs and enthusiast of Scala. TouK has a pleasure to co-sponsor the event. During breaks we'll also look out for a junior Scala developers, so if you're interested, look out for TouK people. Read more
Kolejna partia nagrań z konferencji została udostępniona. Wśród nich m.in. prezentacja Michała Trzaskowskiego o rozpoznawaniu oczekiwań klienta podczas prowadzenia projektu z wykorzystaniem ”zwinnych” metodyk projektowych oraz wystąpienie Macieja Próchniaka o możliwościach Slick, jednej z bibliotek w Scali. Read more