[eis]

  >  Wow, have to ask whether you're interested enough to contribute? :)

Sorry but I don't have a lot of spare time. I think you have some ambition with this project and it'll be a good amount of work.

  > I really don't think I've misused the cache!

Hm what about the scenario I outlined? I might be missing something but I don't see how a cache can be used to check if something exists in persistent data.

  >  I didn't use SQLite because ordinary admins need to be able to inspect and occasionally fix the database.

I see your point though I think any sysadmin nowerdays needs to be able to do basic tasks for databases and especially something like SQLite.

  > TMTP is more like HTTP than SMTP. There must be many ways to host a service, just like a website. Any admin must be able to bring up a TMTP server. (It's nothing like getting a new MTA host to work with the SMTP network!)

Maybe in terms of simplicity of setting up a server yea but other than that this protocol and HTTP have not much in common.

  > And, hey, can't a protocol can be a work in progress? I'm only willing to spec what I am ready to implement! 

Of course. Well, you're trying to build something so more power to you I guess. Just trying to give some constructive criticism even if it initially might have been a bit harsh. Good luck with it anyways!