CODEWITHSUNDEEP
websocket
Nicklas Nielsen
Nicklas Nielsen

Reputation: 23

Websocket frame size specification

This is more a question of interest than necessity;

I am writing a small implication of websocket communication for an embedded system, and found the theoretical size limit of a single frame to be specified at 2^64 bytes.

I have decided to only implement support for the shorter specification of 2^16, but I started wondering, why did they decide to make the max frame size so large, when the specification states that you must use a TCP connection, and TCP has a maximum payload size of 65535 bytes?

Upvotes: 1

Views: 3366

Answers (1)

Myst
Myst

Reputation: 19221

The WebSocket protocol allows each message to be fragmented across multiple TCP/IP packets. This allows a 4Gb message to be split into thousands of TCP/IP packets during transmission.

Note that WebSockets implement a message based protocol over the TCP/IP stream... WebSockets is not a streaming protocol.

For this reason, the TCP/IP packet size limit is irrelevant. The only practical limits are the system's limits and security concerns - can the system handle 64 bit message sizes? is it limited to 32 bits? should users be allowed to send huge messages? what limits should a system impose on the incoming messages in order to prevent users from attacking the system? ... etc'.

Upvotes: 2

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