What is Data Channel? #

Questions From The Curious #

• What’s the difference with TCP?
• How many channels can we have?
• Why do we need data channels?
• Any limit in data size? (max size, 0 byte data?)
• Any limit in bandwidth?
• Can we send binary data? JSON?
• What’s good about data channels?
• Difference from WebSocket?
• How about congestion control?
• How about latency?
• What technologies are used in data channels? (protocol stack)
• How do I know I am sending too much?
• How can I automate the flow control?
• How about unordered traffic like UDP?
• How about unreliable transfers like UDP?
• Would unreliable transfer help to yield low latency?
• Can we send video via data channel?

What does data channels solve? #

• Application examples
  • Real-time network games
  • Game player action events
  • Asset exchange
  • Text chat
  • Collaborative file transfer (distributed storage p2p file sharing)
  • Monitoring IoT devices

Fundamental features #

Reliability #

Congestion avoidance #

Flow control #

Data Channel API #

Connection / Teardown #

Data channel options (label, ID, partial reliability) #

Flow control API (bufferedAmount, threshold event, etc) #

Data Channel in Depth #

SCTP #

Connection establishment flow #

Connection teardown flow #

Keep-alive mechanism #

How does a user message get sent? #

TSN and retransmission #

Congestion avoidance #

Selective ACK #

Fast retransmission/recovery #

DCEP #

Open/ACK handshake #

PPID #

Parameter exchange #

Reference to RFCs #