Monday, August 4, 2014

Help! I'm stuck with DDD Modeling! 8 Tips'n'Tricks to move on.

I was sitting in front of my laptop with a bunch of paper cards scattered all around me. My desk and my windowsill were covered with printed scenarios on the one side and with handwritten sketches of couple of Models on the opposite one. On the monitor, I was browsing photos of previous Modeling sessions and, from time to time, chatting with my friend - an UX Designer.

For last couple of days I was doing the Modeling of a very hard part of our Core Domain. I spoke to Domain Experts in different roles, and I was working closely with the UX Designer, who made a lot of research earlier. I run couple of Modeling sessions - both alone and in groups of 2-5 people. I just couldn't figure out a good enough solution.

I was stuck.

Do You know that feeling?


Have You been in that moment, when you realize, that sometimes Synthesis is not that easy part of the Design process? The moment, when you feel like You are trying to push on a rope? You've done everything correctly, and yet You still cannot find the solution...

I assume, that You are a good scout, and You did Your homework.
  • You have a Context Map somewhere,
  • You did some Event Storming (by Alberto Brandolini),
  • You are focused on some specific Subdomain and have abstracted unimportant things,
  • You have some significant Scenarios in it,
  • You have some Models that fullfill some of those Scenarios,
  • You are actively using Modeling Whirlpool

Everything looks good, but it seems like You can always come with another significant Scenario that will break some already created Models... You are clearly missing some concept and you need to do something different to stop spinning your wheels. 

You need some...

Modeling Tips'n'Tricks


Enter the 8 Tips'n'Tricks that can help You to move on with Modeling activity. I already knew the first 7 and the last one was proposed to me by Mathias Verraes in the Twitter thread. Here You have it, you can take them and use in Your projects.

Monday, February 17, 2014

Well, hello @Mock - we meet again

tl;dr Since I embraced Domain-Driven Design, I didn't have to use any mock.

When in 2011, during Java Developers Day in Kraków, Greg Young stated, that he does not use mocks, I couldn't believe him. I mean, come on! How do you test your code that is dependent on other parts of the code? I was at the very begining of my journey with Domain-Driven Design back then...

Couple of days ago, I had to implement something in old part of the system. This part was developed like most systems were couple of years ago (and some are still) - with Anemic Entities and stateless, so called "Services". I didn't want to refactor this whole spaghetti around that place, so I decided to go with this anemic approach and "just be good enough".

Since I am a big fan of Test-Driven Development (where it is valuable), I decided to write some test for this service that I was about to touch. Suprisingly, there was a test class for this service, and there were even some not that bad unit tests there. Woohoo, lucky me!

I wrote first unit test, run - red of course - so I implemented some simple solution - green - I added another test - red - another simple solution - green - I refactored a little - green. Uncle Bob would be proud!

Then, the time has come to write some more complex case. I realized, that I need some additional service to be injected into mine. It was clear to me, that I needed to mock that service in test, so I wrote
@Mock
private AdditionalService additionalService;
and it felt weird... :/

I realised, that I haven't use mocks for a long time. I just didn't have to.

Thursday, January 2, 2014

2013 summary - books, presentations, trainings, etc.

At this part of the year, many people summarize their last twelve months. So I will.

This year was really busy for me. Especially the second part (hence the lack of my activity on blog).
Not to extend, here are the most important things that I achieved this year, which changed my life, and will be affecting the next one for sure.


1. Books

I read a lot of books this year, but there are three, that affected me the most
  • "Implementing Domain-Driven Design" by Vaughn Vernon - a must-read for any Developer/Analyst/Architect/Whoever-builds-software - just after Eric's "the Blue Book" (or maybe in the meantime). It clearly describes what Domain-Driven Design is and how to implement it (duh, the title). It also gives a little different view at Eric's definitions - 10 years after his publication - and introduces new concepts, that community added to DDD, like Domain Events.
  • "4 Hour Body" by Tim Ferriss - this is not technical book at all, but for me it was a game-changer. It is full of concrete ideas how to master your body - loose weight, gain strength, sleep better and so on. But the biggest thing was the idea to properly set goals, measurements and persist in the way to achieve them. A lot of technical or management people write about the same concepts, but I was able to grasp them finally, thanks to Tim and this totally different domain - human body.
  • "4 Hour Workweek" by Tim Ferriss - after finishing "4 Hour Body" and achieving my goals inspired by it, I decided to dig more into Tim's work - I bought his first book, and took it on my vacation (I love reading on a beach). Tim also writes how to settle goals and achieve them, but a little different kind of goals. The idea of living your life right now and not waiting for retirement is very tempting... and maybe even possible. I will experiment and try some more tricks from this book in the upcoming year.