Unable to send file stream from NodeJS socketio server to python socketio client

user_17819286 0
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I have been trying to use socketio to stream files from nodejs server to the python socketio client. However I don't have a proper idea how to stream image. Currently I am just using readFile in Nodejs. This is what I have written so far to read the file and send it as an whole:

var socket = req.app.get('socket');
readFile(req.file.path, 'utf-8', (err, data) => {
    socket.emit('image', { buffer: data, metadata: req.file }, (response) => {
        console.log(response);
    });
});

On python socketio client's side, I want to save the file to a folder assets and I have written this code:

@sio.event
async def image(data):
    try:
        filehandler = open('assets/' + data['metadata']['filename'] + '.jpeg', 'w')
        filehandler.write(data['buffer'])
        filehandler.close()
    except:
        return 'NOT OK'
    finally:
        return 'OK'

However, the final file written is not readable as an image and I am not able to open it. Please correct my code as required for this to work properly.

Moreover, I want to stream the file from Nodejs instead of reading it whole and then sending it.

I would really appreciate it if I got code for both methods but at least need the code for streaming the file.

Thanks!!

socket.io node.js streaming python
2 Answers

Your question is answered in the usage example of socket.io-stream.

edit: However on the Python side, there seems to be no support:

The Socket.IO protocol doesn't have anything called "streaming". I think you are looking at an extension built by a 3rd party that works on top of the standard Socket.IO packet exchange mechanisms.

user_8333990

I was able to solve this issue for readFile. I removed the 'utf-8' argument from Nodejs and this is the updated code:

readFile(req.file.path, (err, data) => {
    // I used multer so req.file has the file's metadata but doesn't contain buffer
    socket.emit('image', { buffer: data, metadata: req.file }, (response) => {
        console.log(response);
    });
});

On python socketio client's end, I used pillow:

@sio.on('image')
async def tryon(data):
    image = Image.open(io.BytesIO(data['buffer']))
    image.show()
    image.save('assets/' + data['metadata']['filename'] + '.png')
    
    # I tried to write the above code into opencv but was facing errors. 
    # Skipping it for now. You can refer it if you are willing to further debug it.
    # img = cv2.imread(np.frombuffer(data['buffer']))
    # cv2.imwrite('assets/' + data['metadata']['filename'] + '.jpeg', img)

    return 'OK'
user_153476710
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