On 03/08/20 13:36, Daniel P. Berrangé wrote: >>> Given that QEMU needs to pass >>> uint64 values, JSON was simply the wrong choice of format for QMP. > > I wasn't refering to RFC7159. The problem of undefined integer precision > with JSON came up right at the very start when QMP was first designed and > implemented, and has come up again periodically ever since then. libvirt > needed to do workarounds right at the start in 2009, in order to fully > handle signed/unsigned 64-bit integers with QMP.
I assume the workaround you refer to is to store the number as a string and converting it lazily to either an integer or a floating-point type in whoever uses the JSON API. It may not be pretty but probably it would have been the same for any text-based, schema-less protocol. For example, it didn't require writing your own parser. It could be avoided by using a schema in Libvirt, just like QEMU has no problem with it on the other side; it's just a different design choice with different trade-offs, I don't think it's enough of an issue to declare JSON "the wrong choice of format for QMP". Paolo
