On Fri, Jul 31, 2020 at 07:47:01PM +0200, Paolo Bonzini wrote: > On 31/07/20 19:20, Daniel P. Berrangé wrote: > > It also means QMP isn't easily extensible. eg if we used > > HTTP as our base, then we'd get remote TLS support for free from > > whatever library we used. > > ... and we would lose events, unless we do something with HTTP/2 and > streaming responses. We would also have to pass the TLS certificates to > whatever library we used (which might even be using openssl instead of > gnutls). So it's not that simple, and that's why I'm hesitant to see > things as a universal improvement without seeing the code.
I didn't mean to suggest that QEMU should use HTTP, I was just comparing QMP use of JSON vs the common webservices using RST with JSON. HTTP/2 streaming is not required for async events though, there's a variety of ways to do that with HTTP/1.1. Open a HTTP connection and issue GET for /events, and the server will then simply not respond until it has an event ready. Once a event is received, that request is complete. With connection reuse enabled though, another GET request can be made to wait for the next event without the overhead of re-establishing the connection. Alternatively a single HTTP request can be used, but with the response using chunked event so that it can send back an arbitrary unbounded amount of data spread over time. The client can receive and process this data on the fly without waiting for the request to complete. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
