To DDD or not to DDD – Is my model right?

  • “I’m new to DDD, please, help! Can you review my design?”
  • “Can you recommend some DDD code samples?”‘
  • “Why the’re not more DDD samples out there?”

Have you heard any of those before? Maybe it was you asking?

I know how it feels when you are trying to learn something that is really difficult (hello DDD!) and all you hear is “it depends” or “you’re asking a wrong question” (thanks for helping).

The challenge is that both of those answers are true. It’s impossible to give a good answer to any of those questions without having the full context. It’s easy to notice when something is obviously wrong (and you probably know that already anyway), but how do you decide if something is good? How do you know that there’s no better model out there? How do you even know your model is good enough? Is there something like “good enough”? Does DDD come in grades or is it all or nothing thing – either you do it right or not at all?

In that respect DDD is very much like investing.

Some time ago I attended a conference for real-estate investors (landlords). There were many interesting workshops, but my biggest lesson was lunch conversation.

I sat at a table with 3 investors. The first one introduced herself and said she invested in large flats for students and young professionals (flat sharing). The other said it is a really stupid idea. It’s obvious students would ruin your flat sooner or later (he ignored the first investor claiming it never happened to her in the last 10 years). So he invested only in small condos and studios for young working couples. The third observed that small flats tend to have low ROI, so it’s better to buy bigger flats for families. Another advantage is that families change rented flats less often and you don’t have to look for new tenants every few months.

And so it went… For two hours!

It was fascinating. Each investor was making money. Each was happy (and comfortable) with their investment strategy. Each thought that not only is their strategy THE BEST ONE, but that it’s THE ONLY reasonable option. And it was true. Their strategy was the best and only option FOR THEMSELVES.

If you’ve asked them what you should do with your $100 000, each would give you a different answer. All of them would be wrong. Because if you can’t make this decision for yourself then the only thing you should invest in is education. Blindly following other’s people orders won’t make you money in the long term.

Don’t get me wrong. Inspiration is important. Learning from other people’s mistakes is invaluable. It’s OK to ask for advice and consider different viewpoints. The more various options you consider, the better! I’ve learned a lot just by listening to those investors.

But in the end there’s no single best investment strategy and there’s no “right” domain model. You can stop looking now.

The truth is that there are countless strategies and models available. Each has their advantages and disadvantages. Some might be completely wrong, but most would be quite good or good enough for the time being or maybe just satisfactory given the constraints we have. In the end it all depends on your context. And the very important (and mostly ignored) part of that context is… you.

You and everything you know about the business, company and people in there. Your context.

Somebody said that investments are not risky. Investors are risky.  It matters how much you know, what are your past experiences, how well do you get along with your team and stakeholders, how well you deal with pressure, how much risk and overtime are you willing to accept before you talk about it with your PM…

Even if some DDD uber-expert comes to your team for a project and literally tells you what to type for a couple of months, after they leave you’re on your own. Back to square one. Or even worse, because he probably didn’t realize that the “business expert” he talked to is an ignorant know-it-all who has no idea what he’s talking about. He really should’ve talked to that shy, quiet guy in the darkest corner of the open-space. Everybody goes to him when something goes wrong or when they encounter a new edge case.

So don’t fret and start where you are. You already have everything you need at the moment. The rest you can learn by doing and analyzing results. By all means, ask for advice but don’t mistake it with outsourcing thinking.

After doing it 10, 50, 100 times you’d be surprised how much progress you’ve made.

Trust me. Good investors know that there always will be another great opportunity. Good modelers know that there will always be some other good models they could come up with. Don’t get stuck at looking for “perfect solution”. It doesn’t exist.

The better you become, the better will be your results.

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