Innovenergy_trunk/csharp/App/Backend/Websockets/WebsockerManager.cs

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C#
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using System.Net;
using System.Net.Sockets;
using System.Net.WebSockets;
using System.Text;
using System.Text.Json;
using InnovEnergy.App.Backend.Database;
namespace InnovEnergy.App.Backend.Websockets;
public static class WebsocketManager
{
public static Dictionary<Int64, InstallationInfo> InstallationConnections = new Dictionary<Int64, InstallationInfo>();
//Every 2 minutes, check the timestamp of the latest received message for every installation.
//If the difference between the two timestamps is more than two minutes, we consider this installation unavailable.
public static async Task MonitorInstallationTable()
{
while (true){
lock (InstallationConnections){
foreach (var installationConnection in InstallationConnections){
if ((DateTime.Now - installationConnection.Value.Timestamp) > TimeSpan.FromMinutes(1)){
installationConnection.Value.Status = -1;
if (installationConnection.Value.Connections.Count > 0){InformWebsocketsForInstallation(installationConnection.Key);}
}
}
}
await Task.Delay(TimeSpan.FromMinutes(2));
}
}
//Inform all the connected websockets regarding installation "installationId"
public static void InformWebsocketsForInstallation(Int64 installationId)
{
var installation = Db.GetInstallationById(installationId);
var installationConnection = InstallationConnections[installationId];
Console.WriteLine("Update all the connected websockets for installation " + installationId);
var jsonObject = new
{
id = installationId,
status = installationConnection.Status,
testingMode = installation.TestingMode
};
string jsonString = JsonSerializer.Serialize(jsonObject);
byte[] dataToSend = Encoding.UTF8.GetBytes(jsonString);
foreach (var connection in installationConnection.Connections)
{
connection.SendAsync(
new ArraySegment<byte>(dataToSend, 0, dataToSend.Length),
WebSocketMessageType.Text,
true, // Indicates that this is the end of the message
CancellationToken.None
);
}
}
public static async Task HandleWebSocketConnection(WebSocket currentWebSocket)
{
var buffer = new byte[4096];
try
{
while (currentWebSocket.State == WebSocketState.Open)
{
//Listen for incoming messages on this WebSocket
var result = await currentWebSocket.ReceiveAsync(buffer, CancellationToken.None);
if (result.MessageType != WebSocketMessageType.Text)
continue;
var message = Encoding.UTF8.GetString(buffer, 0, result.Count);
var installationIds = JsonSerializer.Deserialize<int[]>(message);
//This is a ping message to keep the connection alive, reply with a pong
if (installationIds[0] == -1)
{
var jsonObject = new
{
id = -1,
status = -1
};
var jsonString = JsonSerializer.Serialize(jsonObject);
var dataToSend = Encoding.UTF8.GetBytes(jsonString);
currentWebSocket.SendAsync(dataToSend,
WebSocketMessageType.Text,
true,
CancellationToken.None
);
continue;
}
//Console.WriteLine("Received a new message from websocket");
lock (InstallationConnections)
{
//Each front-end will send the list of the installations it wants to access
//If this is a new key (installation id), initialize the list for this key and then add the websocket object for this client
//Then, report the status of each requested installation to the front-end that created the websocket connection
foreach (var installationId in installationIds)
{
//Console.WriteLine("New id is "+installationId);
var installation = Db.GetInstallationById(installationId);
if (!InstallationConnections.ContainsKey(installationId))
{
//Console.WriteLine("Create new empty list for installation id " + installationId);
InstallationConnections[installationId] = new InstallationInfo
{
Status = -1
};
}
InstallationConnections[installationId].Connections.Add(currentWebSocket);
var jsonObject = new
{
id = installationId,
status = InstallationConnections[installationId].Status,
testingMode = installation.TestingMode
};
var jsonString = JsonSerializer.Serialize(jsonObject);
var dataToSend = Encoding.UTF8.GetBytes(jsonString);
currentWebSocket.SendAsync(dataToSend,
WebSocketMessageType.Text,
true, // Indicates that this is the end of the message
CancellationToken.None
);
}
Console.WriteLine("Printing installation connection list");
Console.WriteLine("----------------------------------------------");
foreach (var installationConnection in InstallationConnections)
{
Console.WriteLine("Installation ID: " + installationConnection.Key + " Number of Connections: " + installationConnection.Value.Connections.Count);
}
Console.WriteLine("----------------------------------------------");
}
}
lock (InstallationConnections)
{
//When the front-end terminates the connection, the following code will be executed
Console.WriteLine("The connection has been terminated");
foreach (var installationConnection in InstallationConnections)
{
if (installationConnection.Value.Connections.Contains(currentWebSocket))
{
installationConnection.Value.Connections.Remove(currentWebSocket);
}
}
}
await currentWebSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, "Connection closed by server", CancellationToken.None);
lock (InstallationConnections)
{
//Print the installationConnections dictionary after deleting a websocket
Console.WriteLine("Print the installation connections list after deleting a websocket");
Console.WriteLine("----------------------------------------------");
foreach (var installationConnection in InstallationConnections)
{
Console.WriteLine("Installation ID: " + installationConnection.Key + " Number of Connections: " + installationConnection.Value.Connections.Count);
}
Console.WriteLine("----------------------------------------------");
}
}
catch (Exception ex)
{
Console.WriteLine("WebSocket error: " + ex.Message);
}
}
}