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.
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.
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
But
lift framework is also a kind of
framework of frameworks. You can handle own abstraction of
CometActors and push to client javascript that shorten up your way from server to client. So it was the trigger for author of
lift-ng to make a
lift with Angular integration that is build on top of
lift. It provides
AngularActors from which you can
emit/
broadcast events to
scope of
controller.
NgModelBinders that synchronize your backend model with client scope in a few lines! I've used them to send project state (all sprints and thier details) to client and notify him about scrum board changes. My actor doing all of this hard work looks pretty small:
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:
First look
Screenshot of first version:
If you want to look at this closer, check the source code or download ready to run fatjar on
github.
