CQRS - erm OOP and Validations

João P. Bragança
A discussion came up recently on the DDD/CQRS forums recently, that got sidetracked into ‘where do the validations go’ (along with a lot of weird nonsense about async command queues, http status code pedantry, etc, but we’ll leave that for some other time). A large minority of developers - perhaps even a majority - seem to think that validations belong somewhere in the ‘trusted’ client. I find this conclusion strange, as none of the .