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Comment by jongjong | Hacker News Reader

I love sequence diagrams. They are essential for designing complex event-driven system where there are a lot of asynchronous operations. I often use them to make sense of and/or prevent race conditions.

I can also see the value in UML class diagrams for complex OOP systems but for me personally, I can make do without them in the vast majority of cases. They are not as valuable to me as sequence diagrams.

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I still willingly make sequence diagrams to fully document what is happening in a complex system or architecture. I find them to be very useful to get everybody on the same page for the "order of events".

The class diagrams were something I was taught heavily in college and haven't really used since then. Feels like it's just as easy to write down "this object has a one-to-many relationship to this object"

Sequence diagrams force you to think about the flow of control in a system.

When reviewing draft designs, I sometimes ask the author to convert a simple boxes-and-lines architecture diagram to a sequence diagram. It can be revealing.

I can relate. It's an essential communication tool. When discussing asynchronous events with a colleague, there is a point in the discussion when it becomes almost impossible to explain it in words and you really need something like a sequence diagram to communicate accurately.

I never liked UML but I agree time-sequence diagrams can be very helpful.

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