we have a problem regarding Websocket Communication with a Windows-Client.
As minimal setup we use the python3 autobahn websocket ping-pong example.
The server is from (taken from https://github.com/crossbario/autobahn-python/blob/master/examples/asyncio/websocket/echo/server.py). The only modification is that the server sends a message to the client when the connection is opened.
The client is also taken form the autobahn pingpong example but modified in two ways. It accepts connections from a remote server and it does not send a message to the server but it expects one.
This does work well on all browsers on my Linux Machine, but it does not work from a Windows-Client. But if I send a message from the client as soon as the connection is opened, then the client is also able to receive the messages.
Here is the pyhton3 server:
from autobahn.asyncio.websocket import WebSocketServerProtocol, \
WebSocketServerFactory
class MyServerProtocol(WebSocketServerProtocol):
def onConnect(self, req.uest):
print("Client connecting: {0}".format(request.peer))
def onOpen(self):
print("WebSocket connection open.")
self.sendMessage('server hello'.encode('utf8'))
def onMessage(self, payload, isBinary):
if isBinary:
print("Binary message received: {0} bytes".format(len(payload)))
else:
print("Text message received: {0}".format(payload.decode('utf8')))
# echo back message verbatim
self.sendMessage(payload, isBinary)
def onClose(self, wasClean, code, reason):
print("WebSocket connection closed: {0}".format(reason))
if __name__ == '__main__':
import asyncio
factory = WebSocketServerFactory(u"ws://0.0.0.0:9000", debug=False)
factory.protocol = MyServerProtocol
loop = asyncio.get_event_loop()
coro = loop.create_server(factory, '0.0.0.0', 9000)
server = loop.run_until_complete(coro)
try:
loop.run_forever()
except KeyboardInterrupt:
pass
finally:
server.close()
loop.close()
Here is the Websocket Client:
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
var socket = null;
var isopen = false;
window.onload = function() {
socket = new WebSocket("ws://" + location.hostname + ":9000");
socket.onopen = function() {
console.log("Connected!");
isopen = true;
//if I do this, then it works
//socket.send('hello from client'.encode('utf-8'))
}
socket.onmessage = function(e) {
console.log("Text message received: " + e.data);
}
socket.onclose = function(e) {
console.log("Connection closed.");
socket = null;
isopen = false;
}
};
</script>
</head>
<body>
</body>
</html>
Has anybody an idea what I am missing? I want to open a connection from server to client without sending a message from the client first.
Related
We are trying to listen to the kafka topics using js code from browser once the Producer from server side pushes messages to the particular kafka topic.
In the server side, kafka server and zookeeper are running at 9092 and 2181 port respectively.
String topicName = "test";
Properties props = new Properties();
props.put("bootstrap.servers", "localhost:9092");
props.put("acks", "all");
props.put("retries", 0);
props.put("batch.size", 16384);
props.put("linger.ms", 1);
props.put("buffer.memory", 33554432);
props.put("key.serializer",
"org.apache.kafka.common.serialization.StringSerializer");
props.put("value.serializer",
"org.apache.kafka.common.serialization.StringSerializer");
props.put("partitioner.class",
"org.apache.kafka.clients.producer.internals.DefaultPartitioner");
Thread.currentThread().setContextClassLoader(null);
Producer<String, String> producer = new KafkaProducer <String, String>(props);
for(int i = 0; i < 10; i++){
producer.send(new ProducerRecord<String, String>(topicName,
Integer.toString(i), Integer.toString(i) + i));
}
producer.close();
}catch(Exception e){
e.printStackTrace();
}
Client code snippet:
<!DOCTYPE html>
<html>
<head>My Page</head>
<script src="stomp.js"></script>
<script src="http://cdn.sockjs.org/sockjs-0.3.min.js"></script>
<script type="text/javascript">
console.log('Starting: ');
var socket = new SockJS('ws://localhost:9092');
client = Stomp.over(socket);
client.connect( "", "",
function() {
console.log('Connected: ');
client.subscribe("/topic/test",
function( message ) {
alert( message );
}
);
}
);
</script>
</html>
From client side, while we are trying to connect via ws, only the Starting: console is getting printed and Connected: is not getting rpinted since the
websocket connection to the kafka server is not getting succeeded.
Since STOMP is not directly supported for Kafka, we tried to sue SockJS.
Can anyone please help us out to achieve this functionality.
New to JavaScript and Node.js
I have a setup where I have a raspberry pi running Node.js. The raspberry pi is connected to some embedded device through a USB to UART connection with the USB plugged into the raspberry pi. I can send and receive data at this base level just fine. The pi is connected to a router and I access it through it's IP and a browser.
I want to host a simple webpage that has a title, some text, and a button. When I click the button I want my client machine to contact the node.js server and make the pi send a message(already have a message format I am required to use) over the serial port to the embedded device. I want to wait/or not(depends on suggestions) for data to be sent back and then use that data to repopulate the text on the webpage.
What I have is close to this but not complete.
I run a 'server' on node.js off the pi. It uses express and a static page. The static page has a client side JavaScript file that executes a AJAX request when the button is clicked. On the node.js side I have express able to see the AJAX request. I then construct and send my message over serial port to the embedded device using serialport. At this point, on the Node.js side I can send back a string of text/etc. that can be displayed by the webpage but don't know how to somehow wait or other wise receive the data and send it to the webpage for displaying.
Client .html:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Request Sensor Data</title>
<style type="text/css" media="screen"></style>
</head>
<body>
<p>Sensor Data</p>
<p><TEXTAREA id="myTxtArea" NAME="sensorDataTxtBox" ROWS=3 COLS=30 ></TEXTAREA></br>
<button type="button" name="sensorButton" id="mySensorButton" onClick="getSensorData()" >Get Sensor Data</button></p>
<script src="clientCode.js"></script>
</body>
</html>
Client .js:
function getSensorData()
{
console.log('getSensorData() button pushed.');
var xhr = new XMLHttpRequest();
xhr.open('GET', 'sensorGET');
xhr.send(null);
xhr.onreadystatechange = function () {
var DONE = 4; // readyState 4 means the request is done.
var OK = 200; // status 200 is a successful return.
if (xhr.readyState === DONE)
{
if (xhr.status === OK)
{
//insert DOM grabs to set text in html textbox.
console.log(xhr.responseText); // 'This is the returned text.'
var textAreaDOM = document.getElementById('myTxtArea');
textAreaDOM.value = textAreaDOM.value + 'inserted sensor data here\n';
}
else
{
console.log('Error: ' + xhr.status); // An error occurred during the request.
}
}
};
}
node.js .js:
var express = require('express'),
app = express();
app.use('/', express.static(__dirname + '/'));
app.get('/sensorGET', function (req, res) {
var sensorData = getSensorData();
res.send('sensorData');
})
var serialport = require('serialport'),
portname = '/dev/ttyUSB0';
var myPort = new serialport(portname, {
baudRate: 115200,
dataBits: 8,
parity: 'none',
stopBits: 1,
flowControl: false,
parser: serialport.parsers.byteLength(1)
});
myPort.on('open', showPortOpen);
myPort.on('data', recSerialData);
myPort.on('close', showPortClosed);
myPort.on('error', showError);
myPort.on('disconnect', showDisconnect);
function showDisconnect() {
console.log('Someone disconnected');
}
function showPortOpen()
{
console.log('port open. Data rate: ' + myPort.options.baudRate);
}
function recSerialData(data)
{
parseMessage(data);//This function is not shown but parses a message that is sent on the wire
}
function showPortClosed()
{
console.log('port closed.');
}
function showError(error)
{
console.log('Serial port error: ' + error);
}
function getSensorData()
{
myPort.write(Assume correct message is sent here);
//Can return some set text here and it will be written to the webpage.
//example: return "Temp data was asked for...";
//is there a way to wait here for the next message that comes in?
}
Probably the simplest thing will actually be to use something like socket.io and just send the data to the browser with that after every parseMessage. Because for starters if you try to make http wait for all serial data it will likely timeout, and the way things work its just easier to send every time you get a new data event from the serial port.
Client code:
<body>
<input type=text id="input">
</body>
<script>
var connection = new WebSocket('ws://chat-mmnnww123.c9users.io');
/*AFTER CONNECTION*/
$('#input').change(function(){
connection.send(this.value);
$('#input').val("");
alert("DONE");
});
connection.onmessage = function(e){
alert(e.data);
};
</script>
This code just send message write in the input to the server website.
Server code:
var ws = require("nodejs-websocket");
var server = ws.createServer(function(conn){
console.log("New Connection");
//on text function
conn.on("text", function(str){
/*
I want to send this str to agent.html page
*/
conn.sendText("Message send : " + str.toUpperCase());
});
//closing the connection
conn.on("close", function(){
console.log("connection closed");
});
}).listen(process.env.PORT, process.env.IP);
This is the server code which SHOULD take the value in str and pass it to the agent.html page.
Now all I want is to take that str value and pass it to page agent.html that I haven't created yet. This page will help the agent to see the client message.
It should be instant and without refreshing the page.
trying to make a simple text chat socket server. I am very new to coding servers. I have this working code but the problem is that the WebSocket() dies silently on me:
the output in the javascript console is
open
closed
There is very little resources to help me understand this behaviour. Why does my python server kill the connection once the header is sent? Am i sending the response in the correct way? Any help at all would be amazing.
Python code:
import socketserver
import re
from base64 import b64encode
from hashlib import sha1
inited = 0
class MyTCPHandler(socketserver.BaseRequestHandler):
def handle(self):
global inited
if(inited==0):
print(self)
text = self.request.recv(1024).strip()
self.upgradeConnection(text)
self.request.send("a sweet message from the server!".encode("utf-8"));
inited = 1
else:
self.request.sendall("second response!".encode("utf-8"));
def upgradeConnection(self,text):
#print("Client wants to upgrade:")
#print(text);
websocket_answer = (
'HTTP/1.1 101 Switching Protocols',
'Upgrade: websocket',
'Connection: Upgrade',
'Sec-WebSocket-Accept: {key}\r\n\r\n',
)
GUID = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'
#print(re.search(b'Sec-WebSocket-Key:\s+(.*?)[\n\r]+', text))
key = (re.search(b'Sec-WebSocket-Key:\s+(.*?)[\n\r]+', text)
.groups()[0]
.strip())
#print(key.decode("utf-8"))
#print(key.decode("utf-8") + GUID)
#print(sha1((key.decode("utf-8") + GUID).encode("utf-8")))
response_key = b64encode(sha1((key.decode("utf-8") + GUID).encode("utf-8")).digest()).decode("utf-8")
#print(response_key)
response = '\r\n'.join(websocket_answer).format(key=response_key)
self.request.send(response.encode("utf-8"));
HOST, PORT = "localhost", 9999
server = socketserver.TCPServer((HOST, PORT), MyTCPHandler)
server.serve_forever()
Webpage code:
url = "ws://127.0.0.1:9999/";
var sk = new WebSocket(url);
sk.onopen = function(e){
console.log("open");
sk.send("the client is here!!");
}
sk.onmessage = function(e){
console.log("message");
console.log(e.data);
}
sk.onerror = function(e){
console.log("error");
}
sk.onclose = function(e){
console.log("closed");
}
Here is what I am working with:
webserver.py:
import sys
from twisted.internet import reactor
from twisted.python import log
from autobahn.websocket import WebSocketServerFactory, \
WebSocketServerProtocol, \
listenWS
class EchoServerProtocol(WebSocketServerProtocol):
def onMessage(self, msg, binary):
print "sending echo:", msg
self.sendMessage(msg, binary)
if __name__ == '__main__':
log.startLogging(sys.stdout)
factory = WebSocketServerFactory("ws://localhost:9000", debug = False)
factory.protocol = EchoServerProtocol
listenWS(factory)
reactor.run()
background.js:
function updateCookies(info) {
send();
console.log(info.cookie.domain);
}
function send() {
msg = "TEST";
sock.send(msg);
};
var sock = null;
sock = new WebSocket("ws://localhost:9000");
console.log("Websocket created...");
sock.onopen = function() {
console.log("connected to server");
sock.send("CONNECTED TO YOU");
}
sock.onclose = function(e) {
console.log("connection closed (" + e.code + ")");
}
sock.onmessage = function(e) {
console.log("message received: " + e.data);
}
chrome.cookies.onChanged.addListener(updateCookies);
Now, upon running webserver.py and running background.js, nothing happens. The client see's no echo and the server doesn't report any connections or messages. However, if I reload background.js, all the sudden the previous message of "CONNECTED TO YOU" is shown by the server. Reloading again produces the same effect, showing the delayed "CONNECTED TO YOU" message. I've tried running sock.close() after sending the message, but that still produces nothing. I'm really confused at what is causing this random delay. Leaving the server running for 10 - 15 minutes also produces nothing, I must manually refresh the page before I see any messages. Any idea what might be causing this?