Python asyncio streams: No stop byte

Question

While I was writing a program that sends and receive some JSON from a service, I stumbled upon a challenge. The server doesn’t send a stop-byte (not going to lie, took me a few hours to realize it), it’s just byte-by-byte JSON. Not even single quotes.

I was looking for an elegant solution before giving up and doing a while loop that keeps adding byte by byte in a buffer and checking if it’s a valid JSON.

Has anyone ever had to deal with something similar?

Asked By: Guilherme Richter

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Source

Answer 1

The problem was solved by reading byte by byte and adding it to a buffer. Every time I read a byte, I check if the buffer is a valid JSON.

def is_json(string: str) -> bool:
    try:
        json.loads(string)
    except ValueError as e:
        return False
    return True


class MyClient:
# ... my implementation of asyncio's client streams using OOP...

    async def receive(self) -> str:
    # Method used to read data from the server
        msg = ''
        while self.connected:
            data = await self.reader.read(1)
            log.debug(f"Read: {data}")
            msg = msg + data.decode()
            if is_json(msg):
                log.info(f"Received: {msg}")
                return msg
        log.warning(f"Client disconnected!")

Hope this helps someone.

Also, if you have a better/more elegant alternative, please, share.

Answered By: Guilherme Richter

Python asyncio streams: No stop byte

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