Hi!

Regarding the new protocol at
https://github.com/pmienk/libbitcoin_protocol.

I can say it looks really great, I'm (as a wallet developer) just
missing the capability to subscribe for changes so I can get instant
notification. I see that this mechanism was removed.

I see how this is requiring a state in the server about a connection,
but I think polling is not a good solution, it makes things awkward and
slow to react, since instead of getting new information as it comes I
have to be making the same query over and over, with some compromise
between latency and bandwidth that I don't see very optimal.

As a light client user of the protocol, I would like to have a way to
keep any of the actions subscribed so I'm getting new information as it
comes. Otherwise I see it as possible to have a server side component
actually managing this part, on top of polling the server, but seems
like unecessary overhead

Cheers and thanks a lot for all the work put into this!

Pablo