polling for task status.

FarmmapsApi/Extensions.cs

@@ -1,4 +1,7 @@
+using System;
 using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
 using FarmmapsApi.HttpMessageHandlers;
 using FarmmapsApi.Models;
 using FarmmapsApi.Services;
@@ -9,7 +12,8 @@ namespace FarmmapsApi
 {
     public static class Extensions
     {
-        public static IServiceCollection AddFarmmapsServices(this IServiceCollection serviceCollection, Configuration configuration)
+        public static IServiceCollection AddFarmmapsServices(this IServiceCollection serviceCollection,
+            Configuration configuration)
         {
             return serviceCollection
                 .AddSingleton(configuration)
@@ -23,7 +27,26 @@ namespace FarmmapsApi
                 .AddTransient<FarmmapsAuthenticationHandler>()
                 .AddHttpClient<FarmmapsApiService>()
                 .AddHttpMessageHandler<FarmmapsAuthenticationHandler>()
-                .Services;;
+                .Services;
+            ;
+        }
+
+        public static async Task PollTask(TimeSpan retryTime, Func<CancellationTokenSource, Task> callback)
+        {
+            var tokenSource = new CancellationTokenSource();
+            var token = tokenSource.Token;
+            do
+            {
+                try
+                {
+                    await callback(tokenSource);
+                    await Task.Delay(retryTime, token);
+                }
+                catch
+                {
+                    // ignored
+                }
+            } while (!token.IsCancellationRequested);
         }
     }
 }

FarmmapsApi/Services/FarmmapsApiService.cs

@@ -11,8 +11,9 @@ using System.Threading.Tasks;
 using System.Web;
 using FarmmapsApi.Models;
 using IdentityModel;
+using Microsoft.AspNetCore.Http.Connections;
 using Microsoft.AspNetCore.SignalR.Client;
-using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 
@@ -20,6 +21,7 @@ namespace FarmmapsApi.Services
 {
     public class FarmmapsApiService
     {
+        private readonly ILogger<FarmmapsApiService> _logger;
         private readonly HttpClient _httpClient;
         private readonly OpenIdConnectService _openIdConnectService;
         private readonly Configuration _configuration;
@@ -28,9 +30,10 @@ namespace FarmmapsApi.Services
 
         public event Action<EventMessage> EventCallback;
 
-        public FarmmapsApiService(HttpClient httpClient,
+        public FarmmapsApiService(HttpClient httpClient, ILogger<FarmmapsApiService> logger,
             OpenIdConnectService openIdConnectService, Configuration configuration)
         {
+            _logger = logger;
             _httpClient = httpClient;
             _openIdConnectService = openIdConnectService;
             _configuration = configuration;
@@ -65,13 +68,21 @@ namespace FarmmapsApi.Services
             var uri = new Uri(_configuration.Endpoint);
             var eventEndpoint = $"{uri.Scheme}://{uri.Host}:{uri.Port}/EventHub";
             _hubConnection = new HubConnectionBuilder()
-                .WithUrl(eventEndpoint)
+                .WithUrl(eventEndpoint, HttpTransportType.WebSockets, 
+                    options => options.SkipNegotiation = true)
+                .ConfigureLogging(log => log.AddConsole())
                 .WithAutomaticReconnect()
-                .AddJsonProtocol()
                 .Build();
-            _hubConnection.On("Event", (EventMessage @event) => EventCallback?.Invoke(@event));
 
             await _hubConnection.StartAsync();
+            await AuthenticateEventHub(accessToken);
+            
+            _hubConnection.Reconnected += async s => await AuthenticateEventHub(accessToken);
+            _hubConnection.On("event", (Object @event) => _logger.LogInformation(@event.ToString()));
+        }
+
+        private async Task AuthenticateEventHub(string accessToken)
+        {
             await _hubConnection.SendAsync("authenticate", accessToken);
         }
 

FarmmapsApiSamples/NbsApp.cs

@@ -5,6 +5,7 @@ using FarmmapsApi.Models;
 using FarmmapsApi.Services;
 using Microsoft.Extensions.Logging;
 using Newtonsoft.Json.Linq;
+using static FarmmapsApi.Extensions;
 
 namespace FarmmapsApiSamples
 {
@@ -44,30 +45,10 @@ namespace FarmmapsApiSamples
 
                 if (myDriveRoot != null)
                 {
-                    // create or get a cropfield
+                    var cropfieldItem = await GetOrCreateCropfieldItem(myDriveRoot.Code);
-                    var cropfieldItem = await GetCreateCropfieldItem(myDriveRoot.Code);
+                    var targetN = await CalculateTargetN(cropfieldItem, 60);
-                        
+                    
-                    // create or get target n item
+                    _logger.LogInformation($"TargetN: {targetN}");
-
-                    var targetNItems = await
-                        _farmmapsApiService.GetItemChildrenAsync(myDriveRoot.Code, USERINPUT_ITEMTYPE);
-
-                    Item targetNItem;
-                    if (targetNItems.Count == 0)
-                    {
-                        _logger.LogInformation("Creating targetN item");
-                        var itemRequest = CreateTargetNItemRequest(myDriveRoot.Code);
-                        targetNItem = await _farmmapsApiService.CreateItemAsync(itemRequest);
-                    }
-                    else
-                    {
-                        targetNItem = targetNItems[0];
-                    }
-
-                    await CalculateTargetN(cropfieldItem, targetNItem, 60);
-
-
-                    await Task.Delay(2000);
                 }
             }
             catch (Exception ex)
@@ -76,7 +57,7 @@ namespace FarmmapsApiSamples
             }
         }
 
-        private async Task<Item> GetCreateCropfieldItem(string parentItemCode)
+        private async Task<Item> GetOrCreateCropfieldItem(string parentItemCode)
         {
             var cropfieldItems = await
                 _farmmapsApiService.GetItemChildrenAsync(parentItemCode, "vnd.farmmaps.itemtype.cropfield");
@@ -101,8 +82,25 @@ namespace FarmmapsApiSamples
             return await _farmmapsApiService.CreateItemAsync(cropfieldItemRequest);
         }
 
-        private async Task<Item> CalculateTargetN(Item cropfieldItem, Item targetNItem, int targetYield)
+        private async Task<double> CalculateTargetN(Item cropfieldItem, int targetYield)
         {
+            var targetNItems = await
+                _farmmapsApiService.GetItemChildrenAsync(cropfieldItem.ParentCode, USERINPUT_ITEMTYPE);
+
+            Item targetNItem;
+            if (targetNItems.Count == 0)
+            {
+                _logger.LogInformation("Creating targetN item");
+                var itemRequest = CreateTargetNItemRequest(cropfieldItem.ParentCode);
+                targetNItem = await _farmmapsApiService.CreateItemAsync(itemRequest);
+            }
+            else
+            {
+                targetNItem = targetNItems[0];
+            }
+
+            _logger.LogInformation($"Calculating targetN with targetYield: {targetYield}");
+            
             var nbsTargetNRequest = new TaskRequest {TaskType = VRANBS_TASK};
             nbsTargetNRequest.attributes["operation"] = "targetn";
             nbsTargetNRequest.attributes["inputCode"] = targetNItem.Code;
@@ -111,11 +109,19 @@ namespace FarmmapsApiSamples
             nbsTargetNRequest.attributes["targetYield"] = targetYield.ToString();
             string itemTaskCode = await _farmmapsApiService.QueueTaskAsync(cropfieldItem.Code, nbsTargetNRequest);
             
-            // poll task
+            await PollTask(TimeSpan.FromSeconds(3), async (tokenSource) =>
-            
+            {
-            // get target N item again
+                var itemTask = await _farmmapsApiService.GetTaskStatusAsync(cropfieldItem.Code, itemTaskCode);
 
-            return targetNItem;
+                if (itemTask.State != ItemTaskState.Processing && itemTask.State != ItemTaskState.Scheduled)
+                    tokenSource.Cancel();
+            });
+
+            var item = await _farmmapsApiService.GetItemAsync(targetNItem.Code);
+            if (item.Data.ContainsKey("TargetN"))
+                return item.Data["TargetN"].Value<double>();
+            
+            return 0;
         }
 
         private ItemRequest CreateTargetNItemRequest(string parentItemCode)