/// <summary>
/// Keep writing object model updates to the client
/// </summary>
/// <param name="webSocket">WebSocket to write to</param>
/// <param name="subscribeConnection">IPC connection to supply model updates</param>
/// <param name="dataAcknowledged">Event that is triggered when the client has acknowledged data</param>
/// <param name="cancellationToken">Cancellation token</param>
/// <returns>Asynchronous task</returns>
private async Task WriteToClient(WebSocket webSocket, SubscribeConnection subscribeConnection, AsyncAutoResetEvent dataAcknowledged, CancellationToken cancellationToken)
{
do
{
// Wait for the client to acknowledge the receipt of the last JSON object
await dataAcknowledged.WaitAsync(cancellationToken);
if (cancellationToken.IsCancellationRequested)
{
break;
}
// Wait for another object model update and send it to the client
using MemoryStream objectModelPatch = await subscribeConnection.GetSerializedMachineModel(cancellationToken);
await webSocket.SendAsync(objectModelPatch.ToArray(), WebSocketMessageType.Text, true, cancellationToken);
}while (webSocket.State == WebSocketState.Open);
}
static async Task Main(string[] args)
{
// Get an optional filter string
string filter;
if (args.Length > 0 && args[0] != "-")
{
filter = args[0];
}
else
{
Console.WriteLine("Please enter a filter expression or press RETURN to receive partial model updates:");
filter = Console.ReadLine().Trim();
}
// Connect to DCS
using SubscribeConnection connection = new SubscribeConnection();
if (args.Length < 2)
{
await connection.Connect(SubscriptionMode.Patch, filter);
}
else
{
await connection.Connect(SubscriptionMode.Patch, filter, args[1]);
}
Console.WriteLine("Connected!");
// In Patch mode the whole object model is sent over after connecting. Dump it (or call connection.GetMachineModel() to deserialize it)
_ = await connection.GetSerializedMachineModel();
// Then keep listening for (filtered) patches
while (connection.IsConnected)
{
using JsonDocument patch = await connection.GetMachineModelPatch();
if (patch == null)
{
break;
}
Console.WriteLine(GetIndentedJson(patch));
}
}
/// <summary>
/// Deal with a newly opened WebSocket.
/// A client may receive one of the WS codes: (1001) Endpoint unavailable (1003) Invalid command (1011) Internal error
/// </summary>
/// <param name="webSocket">WebSocket connection</param>
/// <param name="socketPath">Path to the UNIX socket</param>
/// <param name="logger">Logger instance</param>
/// <returns>Asynchronous task</returns>
public static async Task Process(WebSocket webSocket, string socketPath, ILogger logger)
{
using (SubscribeConnection connection = new SubscribeConnection())
{
// 1. Authentication
// TODO
// 2. Connect to DCS
try
{
await connection.Connect(SubscriptionMode.Patch, socketPath, Program.CancelSource.Token);
}
catch (AggregateException ae) when(ae.InnerException is IncompatibleVersionException)
{
logger.LogError($"[{nameof(WebSocketController)}] Incompatible DCS version");
await CloseConnection(webSocket, WebSocketCloseStatus.InternalServerError, "Incompatible DCS version");
return;
}
catch (Exception)
{
logger.LogError($"[{nameof(WebSocketController)}] DCS is unavailable");
await CloseConnection(webSocket, WebSocketCloseStatus.EndpointUnavailable, "DCS is unavailable");
return;
}
// 3. Keep the client up-to-date
try
{
// 3a. Fetch full model copy and send it over initially
string json = await connection.GetSerializedMachineModel();
await webSocket.SendAsync(Encoding.UTF8.GetBytes(json), WebSocketMessageType.Text, true, Program.CancelSource.Token);
// 3b. Keep sending updates to the client and wait for "OK" after each update
do
{
// 3c. Wait for response from the client
byte[] receivedBytes = new byte[8];
await webSocket.ReceiveAsync(receivedBytes, Program.CancelSource.Token);
string receivedData = Encoding.UTF8.GetString(receivedBytes);
// 3d. Deal with PING requests
if (receivedData.Equals("PING\n", StringComparison.InvariantCultureIgnoreCase))
{
await webSocket.SendAsync(PONG, WebSocketMessageType.Text, true, Program.CancelSource.Token);
continue;
}
// 3e. Check if the client has acknowledged the received data
if (!receivedData.Equals("OK\n", StringComparison.InvariantCultureIgnoreCase))
{
// Terminate the connection if anything else than "OK" is received
await CloseConnection(webSocket, WebSocketCloseStatus.InvalidMessageType, "Invalid command");
break;
}
// 3f. Check for another update and send it to the client
json = await connection.GetSerializedMachineModel();
await webSocket.SendAsync(Encoding.UTF8.GetBytes(json), WebSocketMessageType.Text, true, Program.CancelSource.Token);
} while (webSocket.State == WebSocketState.Open);
}
catch (Exception e)
{
logger.LogError(e, "WebSocket terminated with an exception");
await CloseConnection(webSocket, WebSocketCloseStatus.InternalServerError, e.Message);
}
}
}
/// <summary>
/// Deal with a newly opened WebSocket.
/// A client may receive one of the WS codes: (1001) Endpoint unavailable (1003) Invalid command (1011) Internal error
/// </summary>
/// <param name="webSocket">WebSocket connection</param>
/// <returns>Asynchronous task</returns>
public async Task Process(WebSocket webSocket)
{
string socketPath = _configuration.GetValue("SocketPath", Defaults.FullSocketPath);
// 1. Authentification. This will require an extra API command
using CommandConnection commandConnection = new CommandConnection();
// TODO
// 2. Connect to DCS
using SubscribeConnection subscribeConnection = new SubscribeConnection();
try
{
// Subscribe to object model updates
await subscribeConnection.Connect(SubscriptionMode.Patch, null, socketPath);
}
catch (AggregateException ae) when(ae.InnerException is IncompatibleVersionException)
{
_logger.LogError($"[{nameof(WebSocketController)}] Incompatible DCS version");
await CloseConnection(webSocket, WebSocketCloseStatus.InternalServerError, "Incompatible DCS version");
return;
}
catch (SocketException)
{
_logger.LogError($"[{nameof(WebSocketController)}] DCS is unavailable");
await CloseConnection(webSocket, WebSocketCloseStatus.EndpointUnavailable, "DCS is unavailable");
return;
}
// 3. Log this event
string ipAddress = HttpContext.Connection.RemoteIpAddress.ToString();
int port = HttpContext.Connection.RemotePort;
_logger.LogInformation("WebSocket connected from {0}:{1}", ipAddress, port);
// 4. Register this client and keep it up-to-date
int sessionId = -1;
try
{
// 4a. Register this user session. Once authentification has been implemented, the access level may vary
await commandConnection.Connect(socketPath);
sessionId = await commandConnection.AddUserSession(AccessLevel.ReadWrite, SessionType.HTTP, ipAddress, port);
// 4b. Fetch full model copy and send it over initially
using (MemoryStream json = await subscribeConnection.GetSerializedMachineModel())
{
await webSocket.SendAsync(json.ToArray(), WebSocketMessageType.Text, true, default);
}
// 4c. Deal with this connection in full-duplex mode
using CancellationTokenSource cts = new CancellationTokenSource();
AsyncAutoResetEvent dataAcknowledged = new AsyncAutoResetEvent();
Task rxTask = ReadFromClient(webSocket, dataAcknowledged, cts.Token);
Task txTask = WriteToClient(webSocket, subscribeConnection, dataAcknowledged, cts.Token);
// 4d. Deal with the tasks' lifecycles
Task terminatedTask = await Task.WhenAny(rxTask, txTask);
cts.Cancel();
if (terminatedTask.IsFaulted)
{
throw terminatedTask.Exception;
}
}
catch (Exception e)
{
_logger.LogError(e, "WebSocket from {0}:{1} terminated with an exception", ipAddress, port);
await CloseConnection(webSocket, WebSocketCloseStatus.InternalServerError, e.Message);
}
finally
{
_logger.LogInformation("WebSocket disconnected from {0}:{1}", ipAddress, port);
try
{
// Try to remove this user session again
await commandConnection.RemoveUserSession(sessionId);
}
catch (Exception e)
{
if (!(e is SocketException))
{
_logger.LogError(e, "Failed to unregister user session");
}
}
}
}
private static async Task Main(string[] args)
{
// Parse the command line arguments
string lastArg = null, socketPath = Defaults.FullSocketPath, filter = null;
bool quiet = false;
foreach (string arg in args)
{
if (lastArg == "-s" || lastArg == "--socket")
{
socketPath = arg;
}
else if (lastArg == "-f" || lastArg == "--filter")
{
filter = arg;
}
else if (arg == "-q" || arg == "--quiet")
{
quiet = true;
}
else if (arg == "-h" || arg == "--help")
{
Console.WriteLine("Available command line arguments:");
Console.WriteLine("-s, --socket <socket>: UNIX socket to connect to");
Console.WriteLine("-f, --filter <filter>: UNIX socket to connect to");
Console.WriteLine("-q, --quiet: Do not display when a connection has been established");
Console.WriteLine("-h, --help: Display this help text");
return;
}
lastArg = arg;
}
// Get an optional filter string
if (string.IsNullOrWhiteSpace(filter))
{
Console.WriteLine("Please enter a filter expression or press RETURN to receive partial model updates:");
filter = Console.ReadLine().Trim();
}
// Connect to DCS
using SubscribeConnection connection = new SubscribeConnection();
await connection.Connect(SubscriptionMode.Patch, filter, socketPath);
if (!quiet)
{
Console.WriteLine("Connected!");
}
// In Patch mode the whole object model is sent over after connecting.
// Dump it (or call connection.GetMachineModel() to deserialize it)
_ = await connection.GetSerializedMachineModel();
// Then keep listening for (filtered) patches
do
{
try
{
using JsonDocument patch = await connection.GetMachineModelPatch();
Console.WriteLine(GetIndentedJson(patch));
}
catch (SocketException)
{
if (!quiet)
{
Console.WriteLine("Server has closed the connection");
}
break;
}
}while (true);
}
