I've successfully followed the instructions for creating a webpage to talk to serial ports found here. And here's the GitHub repository for his project. I've modified it slightly to use Windows COM ports and fake the Arduino data. Now I'm trying to modify it further to talk to one of my company's test boards. I've established two-way communication, so I know I can talk in both directions over the serial port.
Sending id?CRLF over serial to the board will get a response of something like id=91. I can do this in PuTTY by just typing in id? & hitting the Enter key, or in DockLight by creating a send sequence id?rn, both of which work as expected, I get the id=91 response.
However, in the client.js JavaScript, trying to send: socket.send("id?\r\n"); in the console doesn't work, but I see it show up with an extra line in the server response. So I see something like this:
Message received
id?
<=blank line
So I tried to send the ASCII equivalents by doing:
var id = String.fromCharCode(10,13);
socket.send("id?" + id);
Which also doesn't work, although two extra lines show up in the server.
Message received
id?
<=blank line
<=another blank line
EDIT: I've also tried: socket.send('id?\u000d\u000a'); Same results as the first Message received blurb above.
I see the sent command arrive at the server (I've modified it a bit to do a console.log upon receipt of a message from the client):
function openSocket(socket){
console.log('new user address: ' + socket.handshake.address);
// send something to the web client with the data:
socket.emit('message', 'Hello, ' + socket.handshake.address);
// this function runs if there's input from the client:
socket.on('message', function(data) {
console.log("Message received");
console.log(data);
//here's where the CRLF should get sent along with the id? command
myPort.write(data);// send the data to the serial device
});
// this function runs if there's input from the serialport:
myPort.on('data', function(data) {
//here's where I'm hoping to see the response from the board
console.log('message', data);
socket.emit('message', data); // send the data to the client
});
}
I'm not positive that the CRLF is the problem, but I'm pretty sure it is. Possibly it's being swallowed by the server?
How can I embed it in a string to be sent to the server so it get interpreted properly and sent along to the serial port?
Other SO pages I've read:
How can I insert new line/carriage returns into an element.textContent?
JavaScript string newline character?
Well, it turns out that the problem wasn't exactly the CRLF like I thought, it was how the string terminator was being handled. All of our devices use what we can an "S prompt" (s>) for when a command has been processed. When it's done the last thing the board does is return an S prompt, so I'd modified the original server parser code to look for that. However that's a response terminator, not a request terminator. Once I changed it back to parser: serialport.parsers.readline('\n') it started to work.
// serial port initialization:
var serialport = require('serialport'), // include the serialport library
SerialPort = serialport.SerialPort, // make a local instance of serial
portName = process.argv[2], // get the port name from the command line
portConfig = {
baudRate: 9600,
// call myPort.on('data') when a newline is received:
parser: serialport.parsers.readline('\n')
//changed from '\n' to 's>' and works.
//parser: serialport.parsers.readline('s>')
};
Related
I'm definitely a newbie with JS and node. I have telescope management software called SkyX Pro, and it has the ability to run a TCP Server on port 3040. I can connect to it using Netcat and hand it a Javascript starting with //* Javascript *// this works and allows me to startup cameras and other equipment and send commands for taking pictures etc. The issue is it needs to be run from a batch file which makes getting any information back to an HTML page tough (Like Camera, focuser and filter wheel status and temperatures).
The NC call looks like "NC localhost 3040 < Javascript-file.js
To get around the browser to local machine security issues I want to run this from node.js with maybe socket.io-client if possible, but I don't know the proper syntax for it.
I have seen plenty of client syntax sending hello's etc. but nothing send javascript and allowing for two-way connectivity that I can understand.
I have tried using:
var socket = io.connect('http://localhost');`enter code here`
socket.on('httpServer', function (data) {
console.log(data);
document.write(data + "\r\n");
socket.emit('tcp', "For TCP");
});
const net = require('net');
const client = new net.Socket();
client.connect({ port: 3040, host: process.argv[2] });
client.on('data', (data) => {
console.log(data.toString('utf-8'));
But I do not understand it well enough to troubleshoot why it's not working.
Any help would be wonderful, and please treat me like a baby that needs its step by step.
Cheer
Peter
Reading [1], We can assume socket-io isn't the perfect fit for you, because that Server you have sound like a typical tcp-socket server, not a socket.io server ( which requires special headers ) or a web-socket server.
So you only needs "net" library to do the job.
const net = require('net');
// module to send a message to TCP-socket server and wait for the response from socket-server
const sendAndReceive = async (client, message) => {
client.write(message);
let response = null
await ( new Promise( (resolve, reject) => {
client.on('data', function(data) {
response = data;
resolve()
});
}))
return response;
}
// send a single message to the socket-server and print the response
const sendJSCode = (message) => {
// create socket-client
const client = new net.Socket();
client.connect(3040, 'localhost', async function() {
console.log('Connected');
// send message and receive response
const response = await sendAndReceive(client, message)
// parse and print repsonse string
const stringifiedResponse = Buffer.from(response).toString()
console.log('from server: ', stringifiedResponse)
// clean up connection
client.destroy()
});
}
sendJSCode('var Out; \n Out="TheSky Build=" + Application.build \n\r')
This script will:
Initiate a socket client
on connection successfully, client sends a message
client receives back response from that message
client prints response to terminal
Note that TheSkyX has a limitation of 4096 bytes for each message[2], any more than that and we will need to chunk the message. So you may want to keep the js-code short and precise.
that snippet I gave is minimal, it doesn't handle errors from server. If you want, you can add client.on("error", .. ) to handle it.
Your point of connecting to the socket server directly from browser is very intriguing, unfortunately it is not allowed by modern browsers natively due to security concerns 3
[1] https://socket.io/docs/#What-Socket-IO-is-not:~:text=That%20is%20why%20a%20WebSocket%20client,to%20a%20plain%20WebSocket%20server%20either.
[2] https://www.bisque.com/wp-content/scripttheskyx/scriptOverSocket.html#MSearchField:~:text=set%20to%204096%20bytes
I am fairly new to Node.js, and I am creating a TCP client that sends and receives data from a certain server.
My problem is with the "data" event emitted when data is received through the socket.
client.on('data', function(data) {
console.log('[TCP] Client received: ' + data); // Logs the message as it is supposed to be.
console.log(data.split(" ")); // Does not work because it says that data is not a string
});
I tried toString(data) but it did not output it as it was logged by the console.
So my question is: How can I convert this object to a string as it is logged in the console?
Thank you for your input :)
if data is a Buffer instance as it looks like, it's
client.on('data', function(data) {
console.log(data.toString('utf8'));
})
I've got a working HTTP node.js server.
I then created a program on python that uses the socket module to connect to the above server
Please for the time being do not mind the try and except statements. The code's connectTO() function simply connects to a server like any other code, with the exception that it handles some errors. Then the program send the message "hello". Next in the while loop it repeatedly waits for an answer and when it receives one, it prints it.
When I connect to the Node.js http server from python, I do get the message:
"You have just succesfully connected to the node.js server"
Which if you look at my code means that the s.connect(()) command was successful. My problem is that when a request is send to the server, it's supposed to output a message back, but it doesn't.
I also tried sending a message to the server, in which case the server sends back the following message:
HTTP/1.1 400 Bad Request
So why is the server not responding to the requests? Why is it rejecting them?
Python Client:
from socket import AF_INET, SOCK_STREAM, SOL_SOCKET, SO_REUSEADDR
import threading, socket, time, sys
s = socket.socket(AF_INET,SOCK_STREAM)
def connectTO(host,port):
connect = False
count = 0
totalCount = 0
while connect!= True:
try:
s.connect((host,port))
connect = True
print("You have just succesfully connected to the node.js server")
except OSError:
count += 1
totalCount += 1
if totalCount == 40 and count == 4:
print("Error: 404. Connection failed repeatedly")
sys.exit(0)
elif count == 4:
print("Connection failed, retrying...")
count = 0
else:
pass
connectTO("IP_OF_NODE.jS_SERVER_GOES_HERE",777)
message = "hello"
s.send(message.encode("utf-8"))
while True:
try:
data, addr = s.recvfrom(1024)
if data == "":
pass
else:
print(data.decode())
except ConnectionResetError:
print("it seems like we can't reach the server anymore..")
print("This could be due to a change in your internet connection or the server.")
s.close()
Node.js HTTP server:
function onRequest(req, res) {
var postData = "";
var pathname = url.parse(req.url).pathname;
//Inform console of event recievent
console.log("Request for "+pathanme+" received.");
//Set the encoding to equivelant one used in html
req.setEncoding("utf8");
//add a listener for whenever info comes in and output full result
req.addListener("data", function(postDataChunk) {
postData += postDataChunk;
console.log("Received POST data chunk: '"+postDataChunk+"'");
});
req.addListener("end", function() {
route(handle, pathname, res, frontPage, postData);
});
};
http.createServer(onRequest).listen(port,ip);
console.log("Server has started.");
Some of my Research
I should also note that after some research, it seems that an HTTP server accepts HTTP requests, but I don't understand most of what's on Wikipedia. Is this the reason why the server is not responding? And how do I fix that while still using the socket module.
Also there are a lot of similar questions on Stack Overflow, but none help me solve my problem. One of them describes my issue, and the only answer is about "handshakes". Google is also pointless here, but from what I understand it is simply a reaction between the server and the client which defines what the protocol will be. Could this be what I'm missing, and how do I implement it?
Some of these questions also use modules that I'm not ready to use yet like websocket. Either that or they describe a way in which the server connects to the client, which can be done by directly calling python code or connecting to it from Node.js express. I want the client to be the one connecting to an HTTP server, by the means of the socket module in python. For the sake of future visitors who are looking for something like this, here are some of these question:
How to connect node.js app with python script?
Python Client to nodeJS Server with Socket.IO
Python connecting to an HTTP server
A blog that also does something similar to what is described above: https://www.sohamkamani.com/blog/2015/08/21/python-nodejs-comm/
Here is an answer that doesn't actually seem that obvious, but also solves the issue with only the relevant code. People who don't yet no much about servers in general will have probably missed it:
how to use socket fetch webpage use python
You will need to construct an HTTP request.
Example: GET / HTTP/1.1\n\n
Try this:
from socket import AF_INET, SOCK_STREAM, SOL_SOCKET, SO_REUSEADDR
import threading, socket, time, sys
s = socket.socket(AF_INET,SOCK_STREAM)
def connectTO(host,port):
connect = False
count = 0
totalCount = 0
while connect!= True:
try:
s.connect((host,port))
connect = True
print("You have just succesfully connected to the node.js server")
except OSError:
count += 1
totalCount += 1
if totalCount == 40 and count == 4:
print("Error: 404. Connection failed repeatedly")
sys.exit(0)
elif count == 4:
print("Connection failed, retrying...")
count = 0
else:
pass
connectTO("IP_OF_NODE.jS_SERVER_GOES_HERE",777)
message = "GET / HTTP/1.1\n\n"
s.send(message.encode("utf-8"))
while True:
try:
data, addr = s.recvfrom(1024)
if data == "":
pass
else:
print(data.decode())
except ConnectionResetError:
print("it seems like we can't reach the server anymore..")
print("This could be due to a change in your internet connection or the server.")
s.close()
Read this to learn more about HTTP.
Now, I would recommend using this python lib to do what you're trying to do. It makes things much easier. However, if you are 100% set on using raw sockets, then you should make the node server use raw sockets as well. (Assuming you will only be connecting via python). Here is an excellent tutorial
I'm new to node.js and I'm making a simple chat app to get started. I'm a bit confused with the socket.set and socket.get methods.
The way the app works, is - first the client sets its username (pseudo):
function setPseudo() {
if ($("#pseudoInput").val() != "")
{
socket.emit('setPseudo', $("#pseudoInput").val());
$('#chatControls').show();
$('#pseudoInput').hide();
$('#pseudoSet').hide();
}
}
On the server, the pseudo is fetched with:
socket.on('setPseudo', function (data) {
socket.set('pseudo', data);
});
If I understand correctly, the server sets the pseudo variable with data received from this particular client. The server can later get that variable with socket.get. The following code broadcasts a message from a client to all clients:
socket.on('message', function (message) {
socket.get('pseudo', function (error, name) {
var data = { 'message' : message, pseudo : name };
socket.broadcast.emit('message', data);
console.log("user " + name + " send this : " + message);
})
});
What I don't understand is, why can't the client itself use socket.get to fetch its own pseudo? Using socket.get('pseudo') gives an error saying socket.get is not a function. Or am I overcomplicating this, and it would be better to just store the pseudo in a hidden field on the client or something similar? It just feels strange that a client should have to get its own username from the server.
EDIT:
Upon clicking Send, this code displays the sent message on the client itself. However, the displayed username is "Me". How can I modify it to show the client's username from the server?
addMessage($('#messageInput').val(), "Me", new Date().toISOString(), true);
function addMessage(msg, pseudo) {
$("#chatEntries").append('<div class="message"><p>' + pseudo + ' : ' + msg + '</p></div>');
}
You have to realize that although socket is a name used by both the server and the client, and interfaces are similar these are two independent things. (i.e. server socket and client socket) describing two ends of one connection.
If server sets some data on a socket what it actually does is it saves some data in its own memory and remembers that this data is associated with the socket. So how would client read something from server's memory? How can machine A read data from machine's B memory? Well, the only (reasonable) possibility is to send that data over network and this is actually what happens.
As for the other question: it's actually natural for the client to get its own name from the server or at least validate that name. Consider this scenario: two clients connect to the server and use the same name. This would lead to a conflict so it is up to the server to solve the problem. Basically you would tell one of the clients "sorry, this name is already being used, use something else".
After toying around with this for hours, I simply cannot find a solution. I'm working on a WebSocket server using "node.js" for a canvas based online game I'm developing. My game can connect to the server just fine, it accepts the handshake and can even send messages to the server. However, when the server responds to the client, the client doesn't get the message. No errors, nothing, it just sits there peacefully. I've ripped apart my code, trying everything I could think of to fix this, but alas, nothing.
Here's a stripped copy of my server code. As I said before, the handshake works fine, the server receives data fine, but sending data back to the client does not.
var sys = require('sys'),
net = require('net');
var server = net.createServer(function (stream) {
stream.setEncoding('utf8');
var shaken = 0;
stream.addListener('connect', function () {
sys.puts("New connection from: "+stream.remoteAddress);
});
stream.addListener('data', function (data) {
if (!shaken) {
sys.puts("Handshaking...");
//Send handshake:
stream.write(
"HTTP/1.1 101 Web Socket Protocol Handshake\r\n"+
"Upgrade: WebSocket\r\n"+
"Connection: Upgrade\r\n"+
"WebSocket-Origin: http://192.168.1.113\r\n"+
"WebSocket-Location: ws://192.168.1.71:7070/\r\n\r\n");
shaken=1;
sys.puts("Handshaking complete.");
}
else {
//Message received, respond with 'testMessage'
var d = "testMessage";
var m = '\u0000' + d + '\uffff';
sys.puts("Sending '"+m+"' to client");
var result = stream.write(m, "utf8");
/*
Result is equal to true, meaning that it pushed the data out.
Why isn't the client seeing it?!?
*/
}
});
stream.addListener('end', function () {
sys.puts("Connection closed!");
stream.end();
});
});
server.listen(7070);
sys.puts("Server Started!");
Here's my client side code. It uses Chrome native WebSockets.
socket = new WebSocket("ws://192.168.1.71:7070");
socket.onopen = function(evt) {
socket.send("blah");
alert("Connected!");
};
socket.onmessage = function(evt) {
alert(evt.data);
};
var m = '\u0000' + d + '\uffff';
var result = stream.write(m, "utf8");
Ah, that seems not quite right. It should be a zero byte, followed by a UTF-8 encoded string, followed by a 0xFF byte.
\uFFFF does not encode in UTF-8 to a 0xFF byte: you get 0xC3 0xBF. In fact no character will ever produce an 0xFF in UTF-8 encoding: that's why it was picked as a terminator in WebSocket.
I'm not familiar with node.js, but I would guess you'd need to say something like:
stream.write('\u0000'+d, 'utf-8');
stream.write('\xFF', 'binary');
Or manually UTF-8 encode and send as binary.
The handshaking is also questionable, though I guess it's a simple-as-possible first draft that's probably working for you at the moment. You're relying on the first packet being the whole handshake header and nothing else, then the second packet being the payload data. This isn't at all guaranteed. You'll probably want to collect data in a buffer until you see the 0x0D 0x0A 0x0D 0x0A marker for the end of the headers, then check the header content and possibly return the 101, then continue from data after that marker.