All the examples using Microsoft WebSockets over a web-api that I've seen so far use IIS, the implementation is on the get method the HTTP connection is upgraded to a websocket and an instance of websocket handler is passed to the HTTPContext
public HttpResponseMessage Get() {
if (HttpContext.Current.IsWebSocketRequest) {
var noteHandler = new NoteSocketHandler();
HttpContext.Current.AcceptWebSocketRequest(noteHandler);
}
return new HttpResponseMessage(HttpStatusCode.SwitchingProtocols);
}
What am trying to achieve is to do the same on an OWIN pipeline. The problem am facing is the connection is being upgraded to use Websockets but it is not utilizing my websocket handler. Where am I going wrong? Please suggest.
Controller utilizing OwinContext (Followed the example WebSockets in Nancy using OWIN),
public HttpResponseMessage Get() {
IOwinContext owinContext = Request.GetOwinContext();
WebSocketAccept acceptToken = owinContext.Get<WebSocketAccept>("websocket.Accept");
if (acceptToken != null) {
var requestHeaders = GetValue<IDictionary<string, string[]>>(owinContext.Environment, "owin.RequestHeaders");
Dictionary<string, object> acceptOptions = null;
string[] subProtocols;
if (requestHeaders.TryGetValue("Sec-WebSocket-Protocol", out subProtocols) && subProtocols.Length > 0) {
acceptOptions = new Dictionary<string, object>();
// Select the first one from the client
acceptOptions.Add("websocket.SubProtocol", subProtocols[0].Split(',').First().Trim());
}
acceptToken(acceptOptions, async wsEnv => {
var wsSendAsync = (WebSocketSendAsync)wsEnv["websocket.SendAsync"];
var wsRecieveAsync = (WebSocketReceiveAsync)wsEnv["websocket.ReceiveAsync"];
var wsCloseAsync = (WebSocketCloseAsync)wsEnv["websocket.CloseAsync"];
var wsCallCancelled = (CancellationToken)wsEnv["websocket.CallCancelled"];
//should I pass the handler to an event?
var handler = new NoteSocketHAndler();
});
} else {
return new HttpResponseMessage(HttpStatusCode.BadRequest);
}
return new HttpResponseMessage(HttpStatusCode.SwitchingProtocols);
}
Handler Code:
using System;
using Socket = Microsoft.Web.WebSockets;
using Newtonsoft.Json;
public class NoteSocketHandler : Socket.WebSocketHandler {
private static Socket.WebSocketCollection connections = new Socket.WebSocketCollection();
public NoteSocketHandler() {
}
public override void OnOpen() {
connections.Add(this);
}
public override void OnClose() {
connections.Remove(this);
}
public override void OnMessage(string message) {
ChatMessage chatMessage = JsonConvert.DeserializeObject<ChatMessage>(message);
foreach (var connection in connections) {
connection.Send(message);
}
}
}
I finally figured out how to resolve the issue. You can find the code below, also I've written a basic app which uses websockets on OWIN.
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using Microsoft.Owin;
namespace NoteApp.WebService.Controller {
using System;
using System.Net.WebSockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using NoteApp.WebService.Handler;
using WebSocketAccept = System.Action<
System.Collections.Generic.IDictionary<string, object>, // WebSocket Accept parameters
System.Func< // WebSocketFunc callback
System.Collections.Generic.IDictionary<string, object>, // WebSocket environment
System.Threading.Tasks.Task>>;
using WebSocketCloseAsync = System.Func<
int, // closeStatus
string, // closeDescription
System.Threading.CancellationToken, // cancel
System.Threading.Tasks.Task>;
using WebSocketReceiveAsync = System.Func<
System.ArraySegment<byte>, // data
System.Threading.CancellationToken, // cancel
System.Threading.Tasks.Task<
System.Tuple< // WebSocketReceiveTuple
int, // messageType
bool, // endOfMessage
int>>>; // count
// closeStatusDescription
using WebSocketReceiveResult = System.Tuple<int, bool, int>;
using WebSocketSendAsync = System.Func<
System.ArraySegment<byte>, // data
int, // message type
bool, // end of message
System.Threading.CancellationToken, // cancel
System.Threading.Tasks.Task>;
public class NoteController : ApiController {
public HttpResponseMessage Get() {
IOwinContext owinContext = Request.GetOwinContext();
WebSocketAccept acceptToken = owinContext.Get<WebSocketAccept>("websocket.Accept");
if (acceptToken != null) {
var requestHeaders = GetValue<IDictionary<string, string[]>>(owinContext.Environment, "owin.RequestHeaders");
Dictionary<string, object> acceptOptions = null;
string[] subProtocols;
if (requestHeaders.TryGetValue("Sec-WebSocket-Protocol", out subProtocols) && subProtocols.Length > 0) {
acceptOptions = new Dictionary<string, object>();
// Select the first one from the client
acceptOptions.Add("websocket.SubProtocol", subProtocols[0].Split(',').First().Trim());
}
acceptToken(acceptOptions, ProcessSocketConnection);
} else {
return new HttpResponseMessage(HttpStatusCode.BadRequest);
}
return new HttpResponseMessage(HttpStatusCode.SwitchingProtocols);
}
private async Task ProcessSocketConnection(IDictionary<string, object> wsEnv) {
var wsSendAsync = (WebSocketSendAsync)wsEnv["websocket.SendAsync"];
var wsCloseAsync = (WebSocketCloseAsync)wsEnv["websocket.CloseAsync"];
var wsCallCancelled = (CancellationToken)wsEnv["websocket.CallCancelled"];
var wsRecieveAsync = (WebSocketReceiveAsync)wsEnv["websocket.ReceiveAsync"];
//pass the sendasync tuple and the cancellation token to the handler. The handler uses the sendasync method to send message. Each connected client has access to this
var handler = new NoteSocketHandler(wsSendAsync, CancellationToken.None);
handler.OnOpen();
var buffer = new ArraySegment<byte>(new byte[100]);
try {
object status;
while (!wsEnv.TryGetValue("websocket.ClientCloseStatus", out status) || (int)status == 0) {
WebSocketReceiveResult webSocketResultTuple = await wsRecieveAsync(buffer, CancellationToken.None);
int count = webSocketResultTuple.Item3;
handler.OnMessage(Encoding.UTF8.GetString(buffer.Array, 0, count));
}
} catch (Exception ex) {
Console.WriteLine(ex.Message);
throw ex;
}
handler.OnClose();
await wsCloseAsync((int)WebSocketCloseStatus.NormalClosure, "Closing", CancellationToken.None);
}
T GetValue<T>(IDictionary<string, object> env, string key) {
object value;
return env.TryGetValue(key, out value) && value is T ? (T)value : default(T);
}
}
}
