Fragments and control frames
04A large message can be fragmented while Ping and Pong remain responsive between fragments.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 5.4 ↗
RFC 6455 · § 5.4EXAMPLE
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03
Finish the original message.
The final continuation completes the text message in fragment order.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
Read the updated RFC section ↗
Keep control frames independent from message fragments.
- A fragmented message begins with text/binary and FIN=0, continues with opcode 0, and ends with FIN=1.
- Control frames cannot be fragmented and have at most 125 payload bytes. They may appear between message fragments.
- A Ping normally requires a Pong response with the same application data, unless a Close was already received.
Without an extension defining it, fragments of different data messages are not interleaved. An unsolicited Pong is permitted and does not require a response.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
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