/// <summary>
/// Processes initial web socket connection request, sends unreceived messages and keeps websocket connection alive
/// </summary>
/// <param name="context">HttpContext</param>
/// <param name="socketId">Web Socket Id</param>
/// <param name="socketInfo">Web Socket item info</param>
/// <param name="topic">Message topic</param>
/// <returns></returns>
private async Task ProcessRequest(HttpContext context, Guid socketId, WebSocketItemInfo socketInfo, string topic)
{
// Send old messages
var oldMessages = _persistanceService.Get(topic, socketInfo.CreationDT);
foreach (var message in oldMessages)
{
await PushMessageToClient(message, socketInfo.Socket);
}
// Wait in a loop
var buffer = new byte[1024 * 4];
WebSocketReceiveResult result = await socketInfo.Socket.ReceiveAsync(new ArraySegment <byte>(buffer), CancellationToken.None);
while (!result.CloseStatus.HasValue)
{
result = await socketInfo.Socket.ReceiveAsync(new ArraySegment <byte>(buffer), CancellationToken.None);
}
// Close connection
await socketInfo.Socket.CloseAsync(result.CloseStatus.Value, result.CloseStatusDescription, CancellationToken.None);
// Remove from dictionary
ConcurrentDictionary <Guid, WebSocketItemInfo> socketList;
_sockets.TryGetValue(topic, out socketList);
WebSocketItemInfo dummyVar;
socketList.TryRemove(socketId, out dummyVar);
}
/// <summary>
/// Handles web socket requests
/// </summary>
/// <param name="context">HttpContext</param>
/// <param name="options">Middleware options</param>
/// <returns></returns>
public async Task HandleRequest(HttpContext context, LWMessagePushMiddlewareOptions options)
{
try
{
if (context.WebSockets.IsWebSocketRequest)
{
if (!context.Request.Query.ContainsKey("topic"))
{
string err = "Topic is required.";
options.LogListener.Log(string.Format("WebSocket handler error: {0}", err), Logging.LogLevel.Error);
throw new ArgumentNullException(err);
}
string topic = context.Request.Query["topic"];
Guid socketId = Guid.NewGuid();
string lastReceive = context.Request.Query["lastr"];
DateTime lastReceivedMsgDT = DateTime.UtcNow;
options.LogListener.Log(string.Format("WebSocket connection request is received at {0} UTC for {1}", lastReceivedMsgDT.ToString(), topic), Logging.LogLevel.Verbose);
if (lastReceive != null)
{
DateTime.TryParse(lastReceive, out lastReceivedMsgDT);
}
WebSocket webSocket = await context.WebSockets.AcceptWebSocketAsync();
WebSocketItemInfo socketInfo = new WebSocketItemInfo(webSocket, lastReceivedMsgDT);
var newTopicDict = new ConcurrentDictionary <Guid, WebSocketItemInfo>();
newTopicDict.TryAdd(socketId, socketInfo);
_sockets.AddOrUpdate(topic, newTopicDict, (a, b) => { b.TryAdd(socketId, socketInfo); return(b); });
await ProcessRequest(context, socketId, socketInfo, topic);
}
else
{
context.Response.StatusCode = 400;
}
}
catch (Exception e)
{
options.LogListener.Log(string.Format("WebSocket handler error: {0}", e.Message), Logging.LogLevel.Error);
throw e;
}
}