What would redirectClient do:
1: Server executes: redirectClient [[array of player objects or netids],IP:PORT];
2: server checks a config to see if the IP:PORT is in the white-list -- preventing potential RE issues.
3: sends that command to players specified.
4: players fadeIn whit a loading screen while in backend client connects to new server and loads the mission.
5: Profit
Cross map transfers, event servers, multi-server 1 map setups,ETC...
Imagine mill-sim missions if that was possible. Imagine Epoch like gameplay.
Possibility's would be endless.
I highly doubt its possible to use this for anything that high scale. It not being possible with the engine is highly likely. Fat chance just like sendUDPMessage this was implemented for the sole perpouse of having the game send extremly simplistic information to an external debugger in something like Visual Studio for testing back in the pre-alpha/beta and was simply left in there so it wouldn't break anything else by being removed.
In most cases older code isn't removed, its just hidden away so nothing uses it and it just sits there.
similar features are on the long-term wishlist but it's not as simple
A. if target server is unavailable
B. if target server is full
as this would help e.g. side of map transits
would be nice if client could be redirected as early as lobby, to help manage traffic if server reached limit, so if host has another server, redirect there
on second thought server playlist in server config could do.
All of issues you raised there could be sorted by mod/mission makers.
Already making a Dll that would allow cross-server talk between servers.
In my honest opinion BIS dosent need to deal with that. Its up to mod/mission makers to do that. I would never expect BIS doing so due to scale of that work.
Making a Dll that allows cross-server talk is not that hard.
Only thing that BIS would need to do is make server transfer "seamless", eg. No lobby/instant mission load while a loading dialog is displayed.
Well if BIS decides to implement this your idea is amazing. If server is full
have a config where servers are defined and then user gets a prompt "Server full would you like to join blabla".
Well I have requested something like that nearly one year ago: http://feedback.arma3.com/view.php?id=18810
Surely to get around this implmentation you could just add a queing system to arma 3 servers and then you could get asked to join the queue...
Another thing that may be useful - with the redirect, get it to check the server mod list if it's a modded server and load mods on the fly.