5 files changed, 150 insertions, 1 deletions
diff --git a/backend/api/api/Controllers/WebSocketController.cs b/backend/api/api/Controllers/WebSocketController.cs
new file mode 100644
index 00000000..184b47e7
--- /dev/null
+++ b/backend/api/api/Controllers/WebSocketController.cs
@@ -0,0 +1,63 @@
+using api.Services;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+using System.Net.WebSockets;
+
+namespace api.Controllers
+{
+    [Route("api")]
+    [ApiController]
+    public class WebSocketController : ControllerBase
+    {
+        private IMLWebSocketService mlWS;
+        public WebSocketController(IMLWebSocketService mlWS)
+        {
+            this.mlWS = mlWS;
+        }
+
+        [HttpGet("wstest")]
+        public string Test()
+        {
+            this.mlWS.Send("ABC123");
+            return "MESSAGE SENT!";
+        }
+
+        [HttpGet("ws")]
+        public async Task Get()
+        {
+            if (HttpContext.WebSockets.IsWebSocketRequest)
+            {
+                using var webSocket = await HttpContext.WebSockets.AcceptWebSocketAsync();
+                await Echo(webSocket);
+            }
+            else
+            {
+                HttpContext.Response.StatusCode = StatusCodes.Status400BadRequest;
+            }
+        }
+
+        private static async Task Echo(WebSocket webSocket)
+        {
+            var buffer = new byte[1024 * 4];
+            var receiveResult = await webSocket.ReceiveAsync(
+                new ArraySegment<byte>(buffer), CancellationToken.None);
+
+            while (!receiveResult.CloseStatus.HasValue)
+            {
+                await webSocket.SendAsync(
+                    new ArraySegment<byte>(buffer, 0, receiveResult.Count),
+                    receiveResult.MessageType,
+                    receiveResult.EndOfMessage,
+                    CancellationToken.None);
+
+                receiveResult = await webSocket.ReceiveAsync(
+                    new ArraySegment<byte>(buffer), CancellationToken.None);
+            }
+
+            await webSocket.CloseAsync(
+                receiveResult.CloseStatus.Value,
+                receiveResult.CloseStatusDescription,
+                CancellationToken.None);
+        }
+    }
+}
diff --git a/backend/api/api/Program.cs b/backend/api/api/Program.cs
index c8cf0784..5913c2d3 100644
--- a/backend/api/api/Program.cs
+++ b/backend/api/api/Program.cs
@@ -33,6 +33,10 @@ builder.Services.AddScoped<IModelService, ModelService>();
 builder.Services.AddScoped<IPredictorService, PredictorService>();
 builder.Services.AddScoped<IFileService, FileService>();
 
+var mlwss = new MLWebSocketService();
+
+builder.Services.AddSingleton<IMLWebSocketService>(mlwss);
+builder.Services.AddHostedService(_ => mlwss);
 
 builder.Services.AddHostedService<TempFileService>();
 
@@ -54,6 +58,12 @@ builder.Services.AddControllers();
 
 var app = builder.Build();
 
+var webSocketOptions = new WebSocketOptions
+{
+    KeepAliveInterval = TimeSpan.FromMinutes(2)
+};
+
+app.UseWebSockets(webSocketOptions);
 
 //Add Cors
 app.UseCors(
diff --git a/backend/api/api/Services/IMLWebSocketService.cs b/backend/api/api/Services/IMLWebSocketService.cs
new file mode 100644
index 00000000..52efb7fc
--- /dev/null
+++ b/backend/api/api/Services/IMLWebSocketService.cs
@@ -0,0 +1,7 @@
+namespace api.Services
+{
+    public interface IMLWebSocketService
+    {
+        void Send(string message);
+    }
+}
diff --git a/backend/api/api/Services/MLWebSocketService.cs b/backend/api/api/Services/MLWebSocketService.cs
new file mode 100644
index 00000000..ca6919bf
--- /dev/null
+++ b/backend/api/api/Services/MLWebSocketService.cs
@@ -0,0 +1,68 @@
+using System.Net.WebSockets;
+using System.Text;
+
+namespace api.Services
+{
+    public class MLWebSocketService: BackgroundService, IMLWebSocketService
+    {
+        private static readonly string Connection = "ws://localhost:5027";
+
+        private Queue<string> dataQueue = new Queue<string>();
+
+        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+        {
+            while (!stoppingToken.IsCancellationRequested)
+                using (var socket = new ClientWebSocket())
+                    try
+                    {
+                        await socket.ConnectAsync(new Uri(Connection), stoppingToken);
+
+
+                        while(dataQueue.Count > 0)
+                        {
+                            await Send(socket, dataQueue.Dequeue(), stoppingToken);
+                        }
+
+                        Receive(socket, stoppingToken);
+
+                        await socket.CloseAsync(WebSocketCloseStatus.NormalClosure, "", stoppingToken);
+                    }
+                    catch (Exception ex)
+                    {
+                        Console.WriteLine($"ERROR - {ex.Message}");
+                    }
+        }
+
+        private async Task Send(ClientWebSocket socket, string data, CancellationToken stoppingToken) =>
+            await socket.SendAsync(Encoding.UTF8.GetBytes(data), WebSocketMessageType.Text, true, stoppingToken);
+
+        private async Task Receive(ClientWebSocket socket, CancellationToken stoppingToken)
+        {
+            var buffer = new ArraySegment<byte>(new byte[2048]);
+            while (!stoppingToken.IsCancellationRequested)
+            {
+                WebSocketReceiveResult result;
+                using (var ms = new MemoryStream())
+                {
+                    do
+                    {
+                        result = await socket.ReceiveAsync(buffer, stoppingToken);
+                        ms.Write(buffer.Array, buffer.Offset, result.Count);
+                    } while (!result.EndOfMessage);
+
+                    if (result.MessageType == WebSocketMessageType.Close)
+                        break;
+
+                    ms.Seek(0, SeekOrigin.Begin);
+                    using (var reader = new StreamReader(ms, Encoding.UTF8))
+                        Console.WriteLine(await reader.ReadToEndAsync());
+                }
+            };
+        }
+
+        public void Send(string data)
+        {
+            dataQueue.Enqueue(data);
+        }
+    }
+}
diff --git a/backend/api/api/Services/MlConnectionService.cs b/backend/api/api/Services/MlConnectionService.cs
index 7adade0c..9b167537 100644
--- a/backend/api/api/Services/MlConnectionService.cs
+++ b/backend/api/api/Services/MlConnectionService.cs
@@ -1,4 +1,6 @@
 using RestSharp;
+using System.Net.WebSockets;
+using System.Text;
 
 namespace api.Services
 {
@@ -11,7 +13,6 @@ namespace api.Services
             request.AddJsonBody(model);
             var result = await client.ExecuteAsync(request);
             return result.Content;//Response od ML microservisa
-
         }
     }
 }