How DOOM might add support for more than 4 people in SnapMap

[xblade]

I'm not sure how many technical people are on this forum, but here's how I think can SnapMap support more than 4 players.

Since SnapMap works by you hosting a game, I'm guessing that 4 players is the limit for one machine to host, since it's using P2P. What if there are multiple hosts? What if they spread the computational logic to 2 hosts? Maybe one host can handle bullet detection, while another can handle the map triggers and what not. Basically like multi-threaded work, but over the network. Yes this might add latency, but I think it might be done.

If someone has a better understanding on how MP games work, maybe they then chip in their ideas. I myself am a Software Engineer, but I've never worked with games and really have no idea how net-code works in games.

Any thoughts?

[Quasar]

"8-Player SnapMap DLC: Season Pass Edition - $19.99!!!"

[TheMightyHeracross]

Snapmap updates are free.
https://bethesda.net/#en/events/game/doom-open-beta-and-post-launch-content/2016/04/06/101

[Dragonfly]

Bethesda said:

For the rest of the year, we expect to provide certain free content updates across SnapMap and multiplayer.

And yet, here they are with multiple paid Multiplayer DLC's already planned / being charged for.

[PsychoGoatee]

Dragonfly said:

And yet, here they are with multiple paid Multiplayer DLC's already planned / being charged for.

That doesn't contradict what they're saying. In that press release that announced the pay DLC, they mentioned they'll be adding new multiplayer modes for free, new SnapMap stuff for free, etc.

[TheWizard]

I don't know why Snapmap has to be P2P. That, and the 4 player limit thing are really bothering me.

Like I said a while ago in another thread, I get it, if it's P2P why there would be a limitation on players. But that's because there can be monsters in the map too. If it's only players, it should allow more.

But then there is that problem where if you got a few Snapmaps on a maplist that you and your buddies are going through, and one of them happens to be 8 player, then the next is 4 player...what happens? Hell, this is already a problem if you go from a 4 player to a 1 player. It's weird. I wonder how they are solving this.

[Dragonfly]

Yes but TheMightyHeracross implied that all SnapMap updates are free. Bethesdurr say 'some' updates are free. This year.

I'm not intentionally being cynical, but the fact is their wording leaves it open for them to charge for some aspects. Quasar's joke might not actually be a joke.

[DooM_RO]

Dragonfly said:

Yes but TheMightyHeracross implied that all SnapMap updates are free. Bethesdurr say 'some' updates are free. This year.

I'm not intentionally being cynical, but the fact is their wording leaves it open for them to charge for some aspects. Quasar's joke might not actually be a joke.

Tom said Snapmap stuff is free.

[AnonimVio]

DooM_RO said:

Tom said Snapmap stuff is free.

In Tom we trust then.

[tuo]

xblade said:

I'm not sure how many technical people are on this forum, but here's how I think can SnapMap support more than 4 players.

Since SnapMap works by you hosting a game, I'm guessing that 4 players is the limit for one machine to host, since it's using P2P. What if there are multiple hosts? What if they spread the computational logic to 2 hosts? Maybe one host can handle bullet detection, while another can handle the map triggers and what not. Basically like multi-threaded work, but over the network. Yes this might add latency, but I think it might be done.

If someone has a better understanding on how MP games work, maybe they then chip in their ideas. I myself am a Software Engineer, but I've never worked with games and really have no idea how net-code works in games.

Any thoughts?

You'd have to keep the game state in sync between both hosts, and then communicate it to the other hosts. I don't even think the computational part is the bottleneck here. It depends on how complex the gamestate is. That's for example the big problem Star Citizen faces at the moment, taking a pure FPS engine and then trying to make it an MMO. The gamestate is to complex to communicate between many clients, and we are talking dedicated server there.

Planetside for example had many different mechanics in place to conquer similar problems, up to the point that not all players were actually in the same game state. You could have walked besides someone and didn't see him/he didn't see you.

There have been couple of P2P multiplayer modes, I think one CoD even did it, and it worked with many more players. Then again, in these games, you don't have NPCs states to be communicated between hosts.

I guess (and that is pure speculation) that they are playing it safe here, not to run into problems.

Maybe we will see increase in player limit over time? I hope so :)

[Edward850]

xblade said:

Since SnapMap works by you hosting a game, I'm guessing that 4 players is the limit for one machine to host, since it's using P2P.
Any thoughts?

You cannot use the words "host" and "P2P" to describe the same networking environment! If you have a host, that suddenly makes it not P2P in the slightest. They are complete opposite protocols.

Remember: P2P is hostless, such as the BitTorrent protocol. It can survive as long as there's 100% of data between all active nodes. The moment you have a peer that runs a game and a session is dependent on, you have a Client/Server protocol, not P2P!

[tuo]

Edward850 said:

You cannot use the words "host" and "P2P" to describe the same networking environment! If you have a host, that suddenly makes it not P2P in the slightest. They are complete opposite protocols.

Remember: P2P is hostless, such as the BitTorrent protocol. It can survive as long as there's 100% of data between all active nodes. The moment you have a peer that runs a game and a session is dependent on, you have a Client/Server protocol, not P2P!

But the term P2P was used incorrectly in regards to player hosted games, and somehow "stuck" for a time in gaming media, didn't it?

You are 100% correct that P2P actually means that no central host instance is needed.

In gaming terms, that would be close to impossible, since (true) P2P and coherrent game state regarding an FPS game are close to impossible. Note that I especially said FPS. There are MMOs which use P2P, where synchronisation of game state ain't as time critical.

I don't know which game it was exactly, it was some CoD game IIRC, where basically one players machine became the host for the match, and the term "P2P multiplayer" was used. As wrong as it is, actually.

Imagine every Peer in this P2P network has his own gamestate, and they try to negotiate who is right. Welcome to distributed computing, information and cache coherrence etc. pp.

[Edward850]

The actual concept of listen-servers (player hosted games from their own instance) goes all the way back to Quake, so the only thing CoD did there was misappropriated the term (assuming it even did). Automatically arbitrated listen-servers was a Halo2 thing with its matchmaking and party implementation.

What Doom4 is doing here is no different. It's simply a bandwidth concern of running players/AI/scripts at the same time over one physical connection. This kind of data becomes rather tricky to QA without creating static limits, so a 4 player limit would have been picked based on the average users available upstream and the total number of things one can have in a snapmap.

[xblade]

wow, glad to see tech savies here.

stuff got complicated fast... giving everything that was said earlier, i guess 4 was indeed a safe bet.

still, i think they can host the logic on their dedicated server. they already have a hub that hosts the `manifest`. maybe if the game sells well, maybe they can tap into this cloud thing everyone's using. titanfall uses Windows Azure as far as I know.

good chat folks :)

i've learnt something from this...

[Edward850]

xblade said:

still, i think they can host the logic on their dedicated server.

That is far more complicated than you think it is. Remember the bandwidth limitation still exists, so any snapmap that gets hosted will already be under the same bandwidth constraints. A dedicated server in in theory have a bigger pipe, but it's not that you're trying to optimize for, here.
The engine still supports private listen servers, but it can very well also be handing private games to dedicated cloud instances (can't confirm that in the slightest). And if you want both for LAN games and situations where "the cloud" isn't running optimally, you need listen servers to fall back on.

No matter where you put the game, something has to host it, and that takes bandwidth and someone's money. Whether it be your ISP bills or a high maintenance, high cost server farm. And if Halo5 (should have) taught us anything, it's that while dedicated servers a great, relying only them is actually a double edged sword.

[tuo]

Edward850 said:

That is far more complicated than you think it is. Remember the bandwidth limitation still exists, so any snapmap that gets hosted will already be under the same bandwidth constraints.

Depends where you are. I don't know how the situation is all over the world, but for example in Germany where I live, most non-commercial internet connections are not symmetrical, so downstream has a much larger bandwith (and often also much better latency) as upstream.
So if I would be the host, the bottleneck would be my upstream. IIRC, this ain't the case in the US, if I am not mistaken? (not sure, thus why I ask).

I have the feeling that narrow upstreams are why they went a very save route (especially with all the stuff that might run around on the map besides the players) with the player limit. Maybe - when they have gathered enough data to form an opinion - they introduce another metering service, like "you may use so and so much network to make it 8 player, and then it becomes 4 player and you may use more network bandwith".

Of course, this is all speculation

[Edward850]

I can tell you right now that nobody likes being told they can't play a gamemode due to a service they can't/won't control. Somehow in 2016 we've reached a point that people don't fully understand what the limits on their internet service actually mean, other than "I can download this file faster in one household but slower in another". And in other cases, they actually can't control their service due to external factors but still expect access to all the same services. Being told "You can't play this because you live on a farm" isn't actually what people want to hear.

Not to say they can't boost the limit if they feel it's stable enough to do so (they should, absolutely). But honestly it's all pointless speculating about it when the game isn't even out yet.

[tuo]

very true.

Gonna get that WhireShark ready for the first games I host, to see what's actually beeing pushed over those pipes and at what required latency :)