Updated documentation.

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yflu 2023-02-12 12:10:20 +08:00
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@ -75,4 +75,18 @@ Instead of replacing all use of TCP by UDP, it's more reasonable to keep using T
It's not a global consensus, but in practice many UDP communications are platform specific due to their paired asynchronous I/O choices, e.g. epoll in Linux and kqueue in BSD-ish. Of course there're many 3rd party higher level encapsulated tools for cross-platform use but that introduces extra debugging when things go wrong. It's not a global consensus, but in practice many UDP communications are platform specific due to their paired asynchronous I/O choices, e.g. epoll in Linux and kqueue in BSD-ish. Of course there're many 3rd party higher level encapsulated tools for cross-platform use but that introduces extra debugging when things go wrong.
Therefore, the following plan doesn't assume use of any specific 3rd party encapsulation of UDP communication. Therefore, the following plan doesn't assume use of any specific 3rd party encapsulation of UDP communication.
![UDP_secondary_session](./charts/UDPEssentials.jpg) ![UDP_secondary_session](./charts/UDPEssentials.jpg)
# Would using WebRTC for all frontends be a `UDP for all` solution?
Theoretically yes.
## Plan to integrate WebRTC
The actual integration of WebRTC to enable `browser v.s. native app w/ WebRTC` requires detailed planning :)
In my current implementation, there's only 1 backend process and it's responsible for all of the following things. The plan for integrating/migrating each item is written respectively.
- TURN for UDP tunneling/relay
- Some minor modification to [Room.PlayerSecondaryDownsyncSessionDict](https://github.com/genxium/DelayNoMore/blob/365177a3af6033f1cd629a4a4d59beb4557cc311/battle_srv/models/room.go#L126) should be enough to yield a WebRTC API friendly TURN. It's interesting that [though UDP based in transport layer, a WebRTC session is stateful and more similar to WebSocket in terms of API](https://developer.mozilla.org/en-US/docs/Web/API/WebRTC_API).
- STUN for UDP holepunching
- Some minor modification to [Player.UdpAddr](https://github.com/genxium/DelayNoMore/blob/365177a3af6033f1cd629a4a4d59beb4557cc311/battle_srv/models/player.go#L56) should be enough to yield a WebRTC API friendly STUN.
- reconnection recovery
- Not sure whether or not I should separate this feature from STUN and TURN, but if I were to do so, [both `Room.RenderFrameBuffer` and `Room.InputsBuffer`](https://github.com/genxium/DelayNoMore/blob/365177a3af6033f1cd629a4a4d59beb4557cc311/battle_srv/models/room.go) should be moved to a shared fast I/O storage (e.g. using Redis) to achieve the same level of `High Availability` in design as STUN and TURN.

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@ -13,7 +13,7 @@ This project is a demo for a websocket-based rollback netcode inspired by [GGPO]
As lots of feedbacks ask for a discussion on using UDP instead, I tried to summarize my personal opinion about it in [ConcerningEdgeCases](./ConcerningEdgeCases.md) -- **since v0.9.25, the project is actually equipped with UDP capabilities as follows**. As lots of feedbacks ask for a discussion on using UDP instead, I tried to summarize my personal opinion about it in [ConcerningEdgeCases](./ConcerningEdgeCases.md) -- **since v0.9.25, the project is actually equipped with UDP capabilities as follows**.
- When using the so called `native apps` on `Android` and `Windows` (I'm working casually hard to support `iOS` next), the frontends will try to use UDP hole-punching w/ the help of backend as a registry. If UDP hole-punching is working, the rollback is often less than `turn-around frames to recover` and thus not noticeable, being much better than using websocket alone. This video shows how the UDP holepunched p2p performs for [Phone-Wifi v.s. PC-Wifi (viewed by PC side)](https://pan.baidu.com/s/1K6704bJKlrSBTVqGcXhajA?pwd=l7ok). - When using the so called `native apps` on `Android` and `Windows` (I'm working casually hard to support `iOS` next), the frontends will try to use UDP hole-punching w/ the help of backend as a registry. If UDP hole-punching is working, the rollback is often less than `turn-around frames to recover` and thus not noticeable, being much better than using websocket alone. This video shows how the UDP holepunched p2p performs for [Phone-Wifi v.s. PC-Wifi (viewed by PC side)](https://pan.baidu.com/s/1K6704bJKlrSBTVqGcXhajA?pwd=l7ok).
- If UDP hole-punching is not working, e.g. for Symmetric NAT like in 4G/5G cellular network, the frontends will use backend as a UDP tunnel (or relay, whatever you like to call it). This video shows how the UDP tunnel performs for [Phone-4G v.s. PC-Wifi (merged view@v0.9.34, excellent synchronization)](https://pan.baidu.com/s/1yeIrN5TSf6_av_8-N3vdVg?pwd=7tzw). - If UDP hole-punching is not working, e.g. for Symmetric NAT like in 4G/5G cellular network, the frontends will use backend as a UDP tunnel (or relay, whatever you like to call it). This video shows how the UDP tunnel performs for [Phone-4G v.s. PC-Wifi (merged view@v0.9.34, excellent synchronization)](https://pan.baidu.com/s/1yeIrN5TSf6_av_8-N3vdVg?pwd=7tzw).
- Browser vs `native app` is possible but in that case only websocket is used. - Browser vs `native app` is possible but in that case only websocket is used. For WebRTC integration plan please see [ConcerningEdgeCases](./ConcerningEdgeCases.md). You might also be interested in visiting [netplayjs](https://github.com/rameshvarun/netplayjs) to see how others use WebRTC for browser game synchronization as well.
# Notable Features # Notable Features