Signaling Server
The small coordination service peers use to find each other before connecting directly.
A signaling server relays the messages two peers need to exchange in order to establish a direct connection: session descriptions and candidate network paths. Once the connection exists, it carries no further traffic.
It is the irreducible center of an otherwise decentralized design. Peers cannot discover each other from nothing, so something must introduce them — and that something is a server, however small. Recognizing this early prevents a lot of disappointment about how serverless a peer-to-peer architecture really is.
Its saving grace is that it is genuinely small. It holds no application state, stores nothing durable, and handles a message or two per connection. It can be a few dozen lines, it scales trivially, and it can be run on the cheapest infrastructure available.
Two design consequences follow. Room identity is signaling's concern: peers find each other by agreeing on a name, which is why URL-slug lobbies are the natural pattern — the address is the coordination, with no accounts required. And signaling availability is application availability: if the server is unreachable, nobody connects, so surfacing that state honestly is part of the design rather than an edge case.
See also3
WebRTC
The browser standard for direct peer connections carrying audio, video, and arbitrary data.
Networks & Distribution14 connections
Peer-to-Peer
An architecture where participants communicate directly rather than through a central server.
Networks & Distribution13 connections
Conflict-Free Replicated Data Type
A data structure whose replicas can be edited independently and always converge without coordination.
Networks & Distribution12 connections
Related6
Nearby in the graph rather than deliberately chosen. Looser, sometimes surprising.
Linked from9
- Conflict-Free Replicated Data TypeNetworks & Distribution
A data structure whose replicas can be edited independently and always converge without coordination.
- Eventual ConsistencyNetworks & Distribution
A guarantee that replicas converge given no further updates, without guaranteeing when.
- IdempotenceSystems & Tooling
The property that performing an operation twice has the same effect as performing it once.
- NAT TraversalNetworks & Distribution
NAT traversal is the set of tricks two devices behind separate routers use to open a direct connection anyway.
- Network Address TranslationNetworks & Distribution
Rewriting the addresses in packets as they cross a router so that many devices can share one public IPv4 address, a stopgap that became permanent and broke the internet's end-to-end design.
- Peer-to-PeerNetworks & Distribution
An architecture where participants communicate directly rather than through a central server.
- VideoconferencingNetworks & Distribution
Real-time two-way audio and video between people in different places, promised for decades as the picturephone, made ordinary by broadband and webcams, and turned into daily infrastructure for work and school during the 2020 pandemic.
- Virtual Private NetworkNetworks & Distribution
An encrypted tunnel that presents a remote network as local, and the narrow set of things a commercial one actually hides.
- WebRTCNetworks & Distribution
The browser standard for direct peer connections carrying audio, video, and arbitrary data.