#255 - Throw exception when server API version is not supported.

src/Money.Api/Startup.cs

@@ -160,6 +160,7 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
                 p.AllowCredentials();
                 p.AllowAnyHeader();
                 p.SetPreflightMaxAge(TimeSpan.FromMinutes(10));
+                p.WithExposedHeaders(VersionHeader.Name);
             });
 
             app.UseAuthentication();

src/Money.UI.Blazor/Program.cs

@@ -53,6 +53,7 @@ private static void ConfigureServices(IServiceCollection services)
                 .AddSingleton<AuthenticationStateProvider>(provider => provider.GetRequiredService<ApiAuthenticationStateProvider>())
                 .AddSingleton<SignalRListener>()
                 .AddSingleton<ApiHubService>()
+                .AddSingleton<ApiVersionChecker>()
                 .AddTransient<Interop>()
                 .AddSingleton<PwaInstallInterop>()
                 .AddTransient<NetworkStateInterop>()

src/Money.UI.Blazor/Services/ApiClient.cs

@@ -21,6 +21,7 @@ namespace Money.Services
     public class ApiClient
     {
         private readonly ApiClientConfiguration configuration;
+        private readonly ApiVersionChecker versionChecker;
         private readonly HttpClient http;
         private readonly CommandMapper commandMapper;
         private readonly QueryMapper queryMapper;
@@ -29,9 +30,10 @@ public class ApiClient
         private readonly ILog log;
         private readonly Json json;
 
-        public ApiClient(IOptions<ApiClientConfiguration> configuration, HttpClient http, CommandMapper commandMapper, QueryMapper queryMapper, IExceptionHandler exceptionHandler, ApiAuthenticationStateProvider authenticationState, ILogFactory logFactory, Json json)
+        public ApiClient(IOptions<ApiClientConfiguration> configuration, ApiVersionChecker versionChecker, HttpClient http, CommandMapper commandMapper, QueryMapper queryMapper, IExceptionHandler exceptionHandler, ApiAuthenticationStateProvider authenticationState, ILogFactory logFactory, Json json)
         {
             Ensure.NotNull(configuration, "configuration");
+            Ensure.NotNull(versionChecker, "versionChecker");
             Ensure.NotNull(http, "http");
             Ensure.NotNull(commandMapper, "commandMapper");
             Ensure.NotNull(queryMapper, "queryMapper");
@@ -40,6 +42,7 @@ public ApiClient(IOptions<ApiClientConfiguration> configuration, HttpClient http
             Ensure.NotNull(logFactory, "logFactory");
             Ensure.NotNull(json, "json");
             this.configuration = configuration.Value;
+            this.versionChecker = versionChecker;
             this.http = http;
             this.commandMapper = commandMapper;
             this.queryMapper = queryMapper;
@@ -61,8 +64,20 @@ private HttpContent CreateJsonContent<T>(T request)
         private static StringContent CreateStringContent(string requestContent)
             => new StringContent(requestContent, Encoding.UTF8, "text/json");
 
-        private async Task EnsureStatusCodeAsync(HttpResponseMessage responseMessage)
+        private async Task EnsureSuccessResponseAsync(HttpResponseMessage responseMessage)
         {
+            log.Debug($"Api headers: '{responseMessage.Headers}'.");
+
+            if (responseMessage.Headers.TryGetValues(VersionHeader.Name, out var versions))
+            {
+                var rawVersion = versions.FirstOrDefault();
+
+                log.Debug($"ApiVersion is '{rawVersion}'.");
+
+                if (!String.IsNullOrEmpty(rawVersion) && Version.TryParse(rawVersion, out var version))
+                    versionChecker.Ensure(version);
+            }
+
             if (responseMessage.StatusCode == HttpStatusCode.OK)
             {
                 return;
@@ -84,11 +99,11 @@ private async Task EnsureStatusCodeAsync(HttpResponseMessage responseMessage)
 
         private async Task<T> ReadJsonResponseAsync<T>(HttpResponseMessage responseMessage)
         {
+            await EnsureSuccessResponseAsync(responseMessage);
+
             string responseContent = await responseMessage.Content.ReadAsStringAsync();
             log.Debug($"Response: '{responseContent}'.");
 
-            await EnsureStatusCodeAsync(responseMessage);
-
             T response = json.Deserialize<T>(responseContent);
             return response;
         }
@@ -159,7 +174,7 @@ public async Task CommandAsync(Type type, string payload)
             try
             {
                 HttpResponseMessage responseMessage = await PostToUniformApiAsync(commandMapper, "/api/command", type, payload);
-                await EnsureStatusCodeAsync(responseMessage);
+                await EnsureSuccessResponseAsync(responseMessage);
             }
             catch (Exception e)
             {

src/Money.UI.Blazor/Services/ApiVersionChecker.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Money.Services
+{
+    public class ApiVersionChecker
+    {
+        public bool IsPassed(Version version)
+        {
+            // TODO: Check for compatibility.
+            return false;
+        }
+
+        public void Ensure(Version version)
+        {
+            if (!IsPassed(version))
+                throw new NotSupportedApiVersionException(version);
+        }
+    }
+}

src/Money.UI.Blazor/Services/NotSupportedApiVersionException.cs

@@ -0,0 +1,40 @@
+using Neptuo;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Runtime.Serialization;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Money.Services
+{
+    /// <summary>
+    /// Exception raised when server API is not supported by the current client version.
+    /// </summary>
+    [Serializable]
+    public class NotSupportedApiVersionException : Exception
+    {
+        public Version ApiVersion { get; }
+
+        /// <summary>
+        /// Creates a new instance with server api version.
+        /// </summary>
+        /// <param name="apiVersion">The server API version.</param>
+        public NotSupportedApiVersionException(Version apiVersion)
+            : base($"Server API version is 'v{apiVersion}' which is not support by current client version.")
+        {
+            Ensure.NotNull(apiVersion, "apiVersion");
+            ApiVersion = apiVersion;
+        }
+
+        /// <summary>
+        /// Creates new instance for deserialization.
+        /// </summary>
+        /// <param name="info">The serialization info.</param>
+        /// <param name="context">The streaming context.</param>
+        protected NotSupportedApiVersionException(SerializationInfo info, StreamingContext context)
+            : base(info, context)
+        { }
+    }
+}