Develop Reference

Javascript - Arduino - POST request - WiFi101 - Connection issue

In my code I am trying to send a POST request to the IFTTT service webhooks (maker).
I'm using a couple of libraries, mainly WiFi101
I am using an Arduino MKR1000.
I have updated the firmware, and added a certificate for https://maker.ifttt.com:443.
When in the following code I call sslClient.connect(host, 443); It fails to make the connection. I have tried bypassing this and just trying to print data to the host, however this also didn't work.
It takes about 10-20 seconds for the function to return as false, if I change the host to an incorrect variable, then it returns as false immediately. I'm assuming this is a good sign since the arduino is trying to connect?
wifiSetup() Runs well, connection is established reasonably quickly.
The code I am refering to is below:
Globally defined
//WiFi router setup
char ssid[] = "-----"; //network SSID (aka WiFi name)
char pass[] = "-----"; //network password
int status = WL_IDLE_STATUS;
const char* host = "https://maker.ifttt.com";
WiFiSSLClient sslClient;
Wifi setup procedure: This runs without problems
void wifiSetup() {
// Check for the presence of the shield
Serial.print("WiFi101 shield: ");
if (WiFi.status() == WL_NO_SHIELD) {
Serial.println("NOT PRESENT");
return; // don't continue
}
Serial.println("DETECTED");
// attempt to connect to Wifi network:
while ( status != WL_CONNECTED) {
Serial.print("Attempting to connect to Network named: ");
Serial.println(ssid); // print the network name (SSID);
// Connect to WPA/WPA2 network. Change this line if using open or WEP network:
status = WiFi.begin(ssid, pass);
// wait 10 seconds for connection:
delay(10000);
}
printWifiStatus(); // you're connected now, so print out the status
}
The code below is the one causing problems
void sendMessage() {
if (sslClient.connect(host, 443)) {
//change this to your Maker setting from https://ifttt.com/services/maker/settings
String data = "randomdata";
sslClient.println("POST /trigger/tank_empty/with/key/bxa");
sslClient.println("Host: https://maker.ifttt.com");
sslClient.println("Content-Type: application/json");
sslClient.print("Content-Length: ");
sslClient.println(data.length());
sslClient.println();
sslClient.print(data);
sslClient.stop();
Serial.println("IFTTT request Sucessful");
}
else {
Serial.println("IFTTT request failed");
}
delay(20000000);
}
Does anyone have any solutions, or things to troubleshoot?
Thanks for your help all,
Let me know if you need any extra information.

https://maker.ifttt.com is not a valid host. A valid host is either an IP address or a domain. https:// is not a part of the domain, but an URL.
You are also missing the HTTP protocol version (HTTP/1.1), which could potentially cause problems.
const char* host = "maker.ifttt.com";
sslClient.println("POST /trigger/tank_empty/with/key/bxa HTTP/1.1");
sslClient.print("Host: ");
sslClient.println(host); // non hardcoded host header
sslClient.println("Content-Type: application/json");
sslClient.print("Content-Length: ");
sslClient.println(data.length());
sslClient.println();
sslClient.print(data);
sslClient.stop();

signalr - with different clients

I am trying to setup a signalR system.
I have the sample code working, using two browsers and the same hub. messages are sent and received.
Now, when I created a different page, and try to send messages to the hub, it appears to be kinda working, meaning it doesn't blow up, but nothing gets transmitted to the other clients.
I thought I was accessing the same message hub, from all the clients, but maybe I am missing something.
Is it possible to connect different web sites to the same message hub?
Begin Edit
As requested.... here is the code i am using on my second client...
var connection = $.hubConnection('http://xxxxxxxxx.azurewebsites.net/');
var contosoChatHubProxy = connection.createHubProxy('MessagePump');
// contosoChatHubProxy.on('Send', function (name, message) {console.log(name + ' ' + message);});
$.connection.hub.start()
.done(function () {
console.log('Now connected, connection ID=' + $.connection.hub.id); // returns an ID
// $.connection.hub.send('testing', 'this is a test from the client');
// contosoChatHubProxy.send("testing");
// contosoChatHubProxy.invoke('testing', 'this is a test for the client 1');
// contosoChatHubProxy.invoke('say', 'this is a test for the client 2');
// contosoChatHubProxy.invoke('Send', 'This is a test for client 3');
// $.connection.hub.send('testing', 'this is a test from the client 4');
contosoChatHubProxy.invoke('messagePump', 'user', 'this is a test message for 5');
})
.fail(function(){ console.log('Could not Connect!'); });
This is what i am seeing in firebug
From what i can make of the code, the proxy appears to be loading locally, and not even seeing the remote system hub...
My console application(s) that only connect to the remote system hub are able to send and receive messages.
btw - i have tried upper can lower case (MessagePump, messagePump)
but it has not changed the result.

var connection = $.hubConnection('http://xxxxxxxxx.azurewebsites.net/');
You are trying to connect a different website. This http://xxxxxxxxx.azurewebsites.net/ should let cross domain requests.Otherwise you can't connect. If you can manage http://xxxxxxxxx.azurewebsites.net/, you should configure signalr like:
public class Startup
{
public void Configuration(IAppBuilder app)
{
// Branch the pipeline here for requests that start with "/signalr"
app.Map("/signalr", map =>
{
// Setup the CORS middleware to run before SignalR.
// By default this will allow all origins. You can
// configure the set of origins and/or http verbs by
// providing a cors options with a different policy.
map.UseCors(CorsOptions.AllowAll);
var hubConfiguration = new HubConfiguration
{
// You can enable JSONP by uncommenting line below.
// JSONP requests are insecure but some older browsers (and some
// versions of IE) require JSONP to work cross domain
// EnableJSONP = true
};
// Run the SignalR pipeline. We're not using MapSignalR
// since this branch already runs under the "/signalr"
// path.
map.RunSignalR(hubConfiguration);
});
}
}

Connecting to websocket using C# (I can connect using JavaScript, but C# gives Status code 200 error)

I am new in the area of websocket.
I can connect to websocket server using JavaScript using this code:
var webSocket = new WebSocket(url);
But for my application, I need to connect to the same server using c#. The code I am using is:
ClientWebSocket webSocket = null;
webSocket = new ClientWebSocket();
await webSocket.ConnectAsync(new Uri(url), CancellationToken.None);
3rd line of the code results following error:
"Server returned status code 200 when status code 101 was expected"
After little bit of survey, I realised that somehow server can't switch http protocol to websocket protocol during connection process.
Am I doing anything stupid in my C# code or there is something going wrong with the server. I don't have any access to the server, as the url I am using is a third party one .
Could you please give me any suggestion regarding the issue?

TL; DR:
Use ReceiveAsync() in loop until Close frame is received or CancellationToken is canceled. That's how you get your messages. Sending is straightworward, just SendAsync(). Do not use CloseAsync() before CloseOutputAsync() - because you want to stop your receiving loop first. Otherwise - either the CloseAsync() would hang, or if you use CancellationToken to quit ReceiveAsync() - the CloseAsync() would throw.
I learned a lot from https://mcguirev10.com/2019/08/17/how-to-close-websocket-correctly.html .
Full answer:
Use Dotnet client, here, have an example cut out from my real life code, that illustrate how the handshaking is made. The most important thing most people don't understand about how the thing operates is that there is no magic event when a message is received. You create it yourself. How?
You just perform ReceiveAsync() in a loop that ends, when a special Close frame is received. So when you want to disconnect you have to tell the server you close with CloseOutputAsync, so it would reply with a similar Close frame to your client, so it would be able to end receiving.
My code example illustrates only the most basic, outer transmission mechanism. So you send and receive raw binary messages. At this point you cannot tell the specific server response is related to the specific request you've sent. You have to match them yourself after coding / decoding messages. Use any serialization tool for that, but many crypto currency markets use Protocol Buffers from Google. The name says it all ;)
For matching any unique random data can be used. You need tokens, in C# I use Guid class for that.
Then I use request / response matching to make request work without dependency on events. The SendRequest() methods awaits until matching response arrives, or... the connection is closed. Very handy and allows to make way more readable code than in event-based approach. Of course you can still invoke events on messages received, just make sure they are not matched to any requests that require response.
Oh, and for waiting in my async method I use SemaphoreSlim. Each request puts its own semaphore in a special dictionary, when I get the response, I find the entry by the response token, release the semaphore, dispose it, remove from the dictionary. Seems complicated, but it's actually pretty simple.
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.WebSockets;
using System.Threading;
using System.Threading.Tasks;
namespace Example {
public class WsClient : IDisposable {
public int ReceiveBufferSize { get; set; } = 8192;
public async Task ConnectAsync(string url) {
if (WS != null) {
if (WS.State == WebSocketState.Open) return;
else WS.Dispose();
}
WS = new ClientWebSocket();
if (CTS != null) CTS.Dispose();
CTS = new CancellationTokenSource();
await WS.ConnectAsync(new Uri(url), CTS.Token);
await Task.Factory.StartNew(ReceiveLoop, CTS.Token, TaskCreationOptions.LongRunning, TaskScheduler.Default);
}
public async Task DisconnectAsync() {
if (WS is null) return;
// TODO: requests cleanup code, sub-protocol dependent.
if (WS.State == WebSocketState.Open) {
CTS.CancelAfter(TimeSpan.FromSeconds(2));
await WS.CloseOutputAsync(WebSocketCloseStatus.Empty, "", CancellationToken.None);
await WS.CloseAsync(WebSocketCloseStatus.NormalClosure, "", CancellationToken.None);
}
WS.Dispose();
WS = null;
CTS.Dispose();
CTS = null;
}
private async Task ReceiveLoop() {
var loopToken = CTS.Token;
MemoryStream outputStream = null;
WebSocketReceiveResult receiveResult = null;
var buffer = new byte[ReceiveBufferSize];
try {
while (!loopToken.IsCancellationRequested) {
outputStream = new MemoryStream(ReceiveBufferSize);
do {
receiveResult = await WS.ReceiveAsync(buffer, CTS.Token);
if (receiveResult.MessageType != WebSocketMessageType.Close)
outputStream.Write(buffer, 0, receiveResult.Count);
}
while (!receiveResult.EndOfMessage);
if (receiveResult.MessageType == WebSocketMessageType.Close) break;
outputStream.Position = 0;
ResponseReceived(outputStream);
}
}
catch (TaskCanceledException) { }
finally {
outputStream?.Dispose();
}
}
private async Task<ResponseType> SendMessageAsync<RequestType>(RequestType message) {
// TODO: handle serializing requests and deserializing responses, handle matching responses to the requests.
}
private void ResponseReceived(Stream inputStream) {
// TODO: handle deserializing responses and matching them to the requests.
// IMPORTANT: DON'T FORGET TO DISPOSE THE inputStream!
}
public void Dispose() => DisconnectAsync().Wait();
private ClientWebSocket WS;
private CancellationTokenSource CTS;
}
}
BTW, why use other libraries than the .NET built in? I can't find any reason other than maybe poor documentation of the Microsoft's classes. Maybe - if for some really weird reason you would want to use modern WebSocket transport with an ancient .NET Framework ;)
Oh, and I haven't tested the example. It's taken from the tested code, but all inner protocol parts were removed to leave only the transport part.

Since WebsocketSharp is not .NET Core compatible I suggest using websocket-client instead.
Here's some sample code
static async Task Main(string[] args)
{
var url = new Uri("wss://echo.websocket.org");
var exitEvent = new ManualResetEvent(false);
using (var client = new WebsocketClient(url))
{
client.MessageReceived.Subscribe(msg => Console.WriteLine($"Message: {msg}"));
await client.Start();
await client.Send("Echo");
exitEvent.WaitOne();
}
Console.ReadLine();
}
Be sure to use ManualResetEvent. Otherwise it doesn't work.

If you connect with a WebSocket client and you get an HTTP 200 as response, means that probably you are connecting to the wrong place (host, path and/or port).
Basically, you are connecting to a normal HTTP endpoint that is not understanding your WebSocket requirement, and it is just returning the "OK" response (HTTP 200). Probably the WebSocket server runs in another port or path in the same server.
Check your URL.

Not quite sure what happened to WebSocketSharp nuget package, however I noticed that now WebSocket# is showing up as most relevant result in nuget repo. It took me some time before I realized that Connect() is now returning Task, hopefully this example will be useful to someone:
using System;
using System.Threading.Tasks;
using WebSocketSharp;
namespace Example
{
class Program
{
private static void Main(string[] args)
{
using (var ws = new WebSocket(url: "ws://localhost:1337", onMessage: OnMessage, onError: OnError))
{
ws.Connect().Wait();
ws.Send("Hey, Server!").Wait();
Console.ReadKey(true);
}
}
private static Task OnError(ErrorEventArgs errorEventArgs)
{
Console.Write("Error: {0}, Exception: {1}", errorEventArgs.Message, errorEventArgs.Exception);
return Task.FromResult(0);
}
private static Task OnMessage(MessageEventArgs messageEventArgs)
{
Console.Write("Message received: {0}", messageEventArgs.Text.ReadToEnd());
return Task.FromResult(0);
}
}
}

All the libraries mentioned above are Wrappers. The .Net Frameworks class doing this is System.Net.WebSockets.ClientWebSocket

Websocket URLs should start with ws:// or wss:// where the latter is secure websocket.

Listening websocket in MVC

I'm using MVC 4. I have a js code that needs to communicate with the server with the help of Websockets. I'm using Fleck at the server. I'm creating the socket server in Application_Start event. But when I try the connection from browser console, I get errors like Connection refused.
Here is my global.asax code.
protected void Application_Start()
{
IPAddress ip = null;
if (GetResolvedConnecionIPAddress(out ip)) // Get host ip
{
string Domain = "wss" + System.Uri.SchemeDelimiter + ip + ":" + "8092";
FleckLog.Level = Fleck.LogLevel.Debug;
try
{
if (GetResolvedConnecionIPAddress(out ip))
{
var server = new WebSocketServer(Domain);
server.Start(socket =>
{
LogWriter.Logger.Info("WS: Inside socket server");
socket.OnOpen = () =>
{
LogWriter.Logger.Info("WS: OnOpen socket");
};
socket.OnClose = () =>
{
LogWriter.Logger.Info("WS: OnClose socket");
};
socket.OnMessage = message =>
{
LogWriter.Logger.Info("WS: OnMsg socket");
};
});
}
}
catch (Exception e)
{
throw;
}
}
}

It looks like as soon as the Application_Start method ends, that WebSocketServer is going to get out of scope and eventually garbage collected.
You could, set that object as member in the Global class, and dispose it on the Application_End event for example.
UPDATE:
You are also using the wss schema but not providing any certificate configuration. Please note that IIS and Fleck are two different things, that runs in different ports, and not because you create Fleck into the ASP.NET app means that Fleck is going to infer the SSL/TLS configuration or any configuration at all. Try to set the schema to ws instead and open the page without HTTPS and see if it works.

Cross domain from SignalR2 to phantomjs

this project work right on SignalR v1.1.4, client is phantomjs with cors:
webpage = require "webpage"
websocket = webpage.create()
serverUrl = "http://www.domain.com"
websocket.injectJs './jquery-2.1.0.min.js'
websocket.injectJs './jquery.signalR-1.1.4.min.js'
websocket.includeJs serverUrl + '/signalr/hubs', ->
websocket.evaluate (serverUrl)->
$.support.cors = false
$.connection.hub.url = serverUrl + '/signalr'
taskHub = $.connection.taskHub
$.connection.hub.start().done ->
taskHub.server.registerAgent "xxx"
#……
taskHub.client.castTesk = (task) ->
#……
, serverUrl
until upgrade SignalR to v2.0.2.
i remove RouteTable.Routes.MapHubs(new HubConfiguration() { EnableCrossDomain = true }) on Application_Start() and add Startup.cs:
[assembly: OwinStartup(typeof(SpiderMan.Startup))]
namespace ProjectNamespace {
public partial class Startup {
public void Configuration(IAppBuilder app) {
app.Map("/signalr", map => {
map.UseCors(CorsOptions.AllowAll);
var hubConfiguration = new HubConfiguration {
EnableJSONP = true
};
map.RunSignalR(hubConfiguration);
});
}
}
}
then $.connection.hub.start() work right always, but taskHub.client.castTesk() could not be triggered, without any error message.
update:
v1.2.1 is work fail also like v2.0.2.
And, Microsoft.AspNet.SignalR Package with any version on server could not affect this issus. client work right with jquery.signalR-1.1.4.min.js, fail with jquery.signalR-1.2.1.min.js always, for any server signalR version.

You should define your castTesk method before you start your connection. This issue is discussed in the "Connection started before subscriptions are added" section of the SignalR Troubleshooting Guide.
#……
taskHub.client.castTesk = (task) ->
#……
$.connection.hub.start().done ->
taskHub.server.registerAgent "xxx"
#……
The problem is that if you call $.connection.hub.start() before you define taskHub.client.castTesk, SignalR will not subscribe the client to the TaskHub.
You will still be able to invoke server-side methods belonging to the TaskHub such as RegisterAgent, but the server will be unable to invoke client methods such as castTesk.
I would also suggest removing the $.support.cors = false line. This will cause SignalR to always use JSONP instead of CORS even if the browser supports CORS.