* clustering - what kinds of clusters are supported? How do they scale? Do they favor availability or consistency?
* security - is there any authentication? authorization for certain resources? TLS?
* guarantuees for delivery? Transactional modes?
* what does the wire protocol look like? Support for meta data?
I clicked around the website and documentation a bit, and didn't find any answers.
There is no persistence so consistency is irrelevant. NATS does everything in the name of availability to the point of dropping connections for slow consumers.
> * security - is there any authentication? authorization for certain resources? TLS?
TLS is planned, not sure on timeline. It sounds like Apcera has plans for some form of authentication and multitenancy as well.
> * guarantuees for delivery? Transactional modes?
At-most-once delivery. No transactions. There may be some form of more reliable delivery coming in the future, but I'm not sure of the details.
> * what does the wire protocol look like? Support for meta data?
Very simple text-based protocol. I don't think it's formally documented anywhere currently though.
(Disclaimer: I work for Apcera)