asyncio stream vs synchronous stream in socket communication with a react native app - react-native

Question

Objective is esp32 running micropython acts as a server while android app acts as a client. Before asyncio stream I am able to communicate successfully, but after switching to asyncio i fail to do so, only android app to esp32 is successful but app is failing to retrieve json output from server and I even tried text strings too . App side code remains unchanged for both synchronous/asyncio codes.
Desired output:
response = {
'error': 'invalid request',
'status': 'retry'
}
synchronous side:
conn.send('HTTP/1.1 200 OK\n')
conn.send('Content-Type: application/json\n')
conn.send('Connection: close\n\n')
conn.sendall(ujson.dumps(response ))
asyncio side:
swriter.write(ujson.dumps(response ))
await swriter.drain()
react native side:
fetch( 'http://192.168.0.110' )
.then(response => response.json())
.then((responseJson) => {
const data1 = responseJson;
console.log('getting data from fetch', data1)
setData({ data1 });
onConnectionMessage(data1);
})
synchronous way I was able to retrieve the json output sent from esp32 to android app(react native), but the same code using asyncio failed. What am I doing wrong?
sample asyncio server side code is:
import usocket as socket
import uasyncio as asyncio
import uselect as select
import ujson
from heartbeat import heartbeat # Optional LED flash
class Server:
def __init__(self, host='0.0.0.0', port=80, backlog=5, timeout=10):
self.host = host
self.port = port
self.backlog = backlog
self.timeout = timeout
async def run(self):
print('Awaiting client connection.')
self.cid = 0
asyncio.create_task(heartbeat(100))
self.server = await asyncio.start_server(self.run_client, self.host, self.port, self.backlog)
while True:
await asyncio.sleep(100)
async def run_client(self, sreader, swriter):
self.cid += 1
print('Got connection from client', self.cid)
try:
while True:
try:
res = await asyncio.wait_for(sreader.readline(), self.timeout)
except asyncio.TimeoutError:
res = b''
if res == b'':
raise OSError
print('Received {} from client {}'.format(ujson.loads(res.rstrip()), self.cid))
response = {
'error': 'invalid request',
'status': 'retry'
}
swriter.write(ujson.dumps(response))
await swriter.drain() # Echo back
except OSError:
pass
print('Client {} disconnect.'.format(self.cid))
await sreader.wait_closed()
print('Client {} socket closed.'.format(self.cid))
async def close(self):
print('Closing server')
self.server.close()
await self.server.wait_closed()
print('Server closed.')
server = Server()
try:
asyncio.run(server.run())
except KeyboardInterrupt:
print('Interrupted') # This mechanism doesn't work on Unix build.
finally:
asyncio.run(server.close())
_ = asyncio.new_event_loop()

Answer 1

got the error: asyncio.wait_for(sreader.readline(), self.timeout)------> changed to
asyncio.wait_for(sreader.read(2048), self.timeout). Now client is recieving json output immediately after closing the socket