Sending data as binary via websockets encodes numbers as text

I'm working on a project where I'll be sending binary data across a websocket connection to an LED matrix. I want to send the binary data in the form of a byte array, e.g. drawing a diagonal line from right to left on the matrix would look like this:

0b00000001  0b00000010  0b00000100  0b00001000  0b00010000  0b00100000  0b01000000  0b10000000  

The problem that I run into when I try to do this is that when I try to send this data, regardless of the websocket client tester I use, the numbers get encoded as strings.

That is, when I try to send the binary number 1, instead of sending a 0x01, the socket client sends a 49 in decimal/0x31 in hex which is the character code for the string '1' in ascii or unicode.

At first I thought this issue was on the arduino side in the code that's driving the matrix, but then I traced it back through the websocket server and all of the way to the testing clients. If I pop up wireshark and look at the data in flight from the client to the server, the encoding happens at the client, i.e. the first part of the websocket transmission.

I thought this may be me just using Firecamp wrong, but the same thing happens when using a different client, in this case websocat:

So, my question is: what is the proper way of sending binary numbers via websockets? Am I just misunderstanding how the binary feature is supposed to work, like is it expected that I send my numbers as strings and convert them back to numbers on the other side?

https://stackoverflow.com/questions/65449143/sending-data-as-binary-via-websockets-encodes-numbers-as-text December 25, 2020 at 10:55PM