[cryptoxchange]

I agree with you in general.

However, in your example it’s the kernel that is deciding the request (message) is bad. In Hubris it is the message receiver.

This is a bit contrived, but imagine you’re receiving some stringly typed data from an external source and sending a message to a parsing task that either throws or messages you back with a list of some type t. Maybe it is returning ints and you as the client know that if something isn’t parsable as an int you want it to treat it as a ‘0’ because you’re summing the list. Somewhere else you want to call the same task, but you want strings that can’t be parsed to be treated as ‘1’ unless they can’t be parsed due to overflow (in which case you rethrow) because you’re taking the product.

In some situations it’s natural for the client to know more than the server about how to handle errors. With this nuke from orbit model, there’s some forced coupling between the client and server (mutual agreement over what causes a REPLY_FAULT).