posted 10 years ago
I use sequence diagrams a lot and I wanted to pick up on your concern about which way the arrows run. I find it more pleasing when calls all go left to right and returns all go right to left, but it can't always be done. Callback methods come to mind as one exception. Other cases might expose circular dependencies and may indeed be bad ... or not. Anyhow, I wouldn't worry that there is any rule against calls going right to left.