SEBWIN-219: Started refining communication API & mechanics.

SafeExamBrowser.Client/Behaviour/ClientController.cs

@@ -86,6 +86,7 @@ namespace SafeExamBrowser.Client.Behaviour
 			if (success)
 			{
 				RegisterEvents();
+				// TODO: Handle communication exception!
 				runtime.InformClientReady();
 				splashScreen.Hide();
 
@@ -174,14 +175,9 @@ namespace SafeExamBrowser.Client.Behaviour
 
 		private void Taskbar_QuitButtonClicked()
 		{
-			// TODO: MessageBox asking whether user really wants to quit -> args.Cancel
-
-			var acknowledged = runtime.RequestShutdown();
-
-			if (!acknowledged)
-			{
-				logger.Warn("The runtime did not acknowledge the shutdown request!");
-			}
+			// TODO: MessageBox asking whether user really wants to quit -> only then request shutdown!
+			// TODO: Handle communication exception!
+			runtime.RequestShutdown();
 		}
 
 		private void WindowMonitor_WindowChanged(IntPtr window)

SafeExamBrowser.Contracts/Communication/IClientProxy.cs

@@ -15,11 +15,13 @@ namespace SafeExamBrowser.Contracts.Communication
 		/// <summary>
 		/// Instructs the client to initiate its shutdown procedure.
 		/// </summary>
+		/// <exception cref="System.ServiceModel.*">If the communication failed.</exception>
 		void InitiateShutdown();
 
 		/// <summary>
 		/// Instructs the client to submit its authentication data.
 		/// </summary>
+		/// <exception cref="System.ServiceModel.*">If the communication failed.</exception>
 		AuthenticationResponse RequestAuthentication();
 	}
 }

SafeExamBrowser.Contracts/Communication/ICommunicationProxy.cs

@@ -13,13 +13,15 @@ namespace SafeExamBrowser.Contracts.Communication
 	public interface ICommunicationProxy
 	{
 		/// <summary>
-		/// Tries to establish a connection. Returns <c>true</c> if successful, otherwise <c>false</c>.
+		/// Tries to establish a connection. Returns <c>true</c> if the connection has been accepted, otherwise <c>false</c>.
 		/// </summary>
+		/// <exception cref="System.ServiceModel.*">If the communication failed.</exception>
 		bool Connect(Guid? token = null);
 
 		/// <summary>
-		/// Terminates an open connection. Returns <c>true</c> if successful, otherwise <c>false</c>.
+		/// Terminates an open connection. Returns <c>true</c> if the disconnection has been acknowledged, otherwise <c>false</c>.
 		/// </summary>
+		/// <exception cref="System.ServiceModel.*">If the communication failed.</exception>
 		bool Disconnect();
 	}
 }

SafeExamBrowser.Contracts/Communication/IRuntimeProxy.cs

@@ -15,18 +15,19 @@ namespace SafeExamBrowser.Contracts.Communication
 		/// <summary>
 		/// Retrieves the application configuration from the runtime.
 		/// </summary>
-		/// <exception cref="System.ServiceModel.CommunicationException">If the configuration could not be retrieved.</exception>
+		/// <exception cref="System.ServiceModel.*">If the communication failed.</exception>
 		ClientConfiguration GetConfiguration();
 
 		/// <summary>
 		/// Informs the runtime that the client is ready.
 		/// </summary>
-		/// <exception cref="System.ServiceModel.CommunicationException">If the runtime did not acknowledge the status update.</exception>
+		/// <exception cref="System.ServiceModel.*">If the communication failed.</exception>
 		void InformClientReady();
 
 		/// <summary>
-		/// Requests the runtime to shut down the application. Returns <c>true</c> if the request was acknowledged, otherwise <c>false</c>.
+		/// Requests the runtime to shut down the application.
 		/// </summary>
-		bool RequestShutdown();
+		/// <exception cref="System.ServiceModel.*">If the communication failed.</exception>
+		void RequestShutdown();
 	}
 }

SafeExamBrowser.Contracts/Communication/IServiceProxy.cs

@@ -22,11 +22,13 @@ namespace SafeExamBrowser.Contracts.Communication
 		/// <summary>
 		/// Instructs the service to start a new session according to the given parameters.
 		/// </summary>
+		/// <exception cref="System.ServiceModel.*">If the communication failed.</exception>
 		void StartSession(Guid sessionId, Settings settings);
 
 		/// <summary>
 		/// Instructs the service to stop the specified session.
 		/// </summary>
+		/// <exception cref="System.ServiceModel.*">If the communication failed.</exception>
 		void StopSession(Guid sessionId);
 	}
 }

SafeExamBrowser.Contracts/Communication/Responses/SimpleResponsePurport.cs

@@ -18,6 +18,11 @@ namespace SafeExamBrowser.Contracts.Communication.Responses
 		/// </summary>
 		Acknowledged = 1,
 
+		/// <summary>
+		/// Signals an interlocutor that it is not authorized to communicate.
+		/// </summary>
+		Unauthorized,
+
 		/// <summary>
 		/// Signals an interlocutor that a message has not been understood.
 		/// </summary>

SafeExamBrowser.Core/Communication/BaseHost.cs

@@ -97,7 +97,7 @@ namespace SafeExamBrowser.Core.Communication
 		{
 			lock (@lock)
 			{
-				var response = default(Response);
+				var response = new SimpleResponse(SimpleResponsePurport.Unauthorized) as Response;
 
 				if (IsAuthorized(message?.CommunicationToken))
 				{

SafeExamBrowser.Core/Communication/RuntimeProxy.cs

@@ -37,21 +37,23 @@ namespace SafeExamBrowser.Core.Communication
 		{
 			var response = Send(SimpleMessagePurport.ClientIsReady);
 
-			if (!IsAcknowledgeResponse(response))
+			if (!IsAcknowledged(response))
 			{
 				throw new CommunicationException($"Runtime did not acknowledge that client is ready! Response: {ToString(response)}.");
 			}
 		}
 
-		public bool RequestShutdown()
+		public void RequestShutdown()
 		{
 			var response = Send(SimpleMessagePurport.RequestShutdown);
-			var acknowledged = IsAcknowledgeResponse(response);
 
-			return acknowledged;
+			if (!IsAcknowledged(response))
+			{
+				throw new CommunicationException($"Runtime did not acknowledge shutdown request! Response: {ToString(response)}.");
+			}
 		}
 
-		private bool IsAcknowledgeResponse(Response response)
+		private bool IsAcknowledged(Response response)
 		{
 			return response is SimpleResponse simpleResponse && simpleResponse.Purport == SimpleResponsePurport.Acknowledged;
 		}

SafeExamBrowser.Runtime.UnitTests/Behaviour/Operations/SessionSequenceOperationTests.cs

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2018 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace SafeExamBrowser.Runtime.UnitTests.Behaviour.Operations
+{
+	[TestClass]
+	public class SessionSequenceOperationTests
+	{
+		[TestMethod]
+		public void TODO()
+		{
+			Assert.Fail();
+		}
+	}
+}

SafeExamBrowser.Runtime.UnitTests/SafeExamBrowser.Runtime.UnitTests.csproj

@@ -83,6 +83,7 @@
     <Compile Include="Behaviour\Operations\ConfigurationOperationTests.cs" />
     <Compile Include="Behaviour\Operations\KioskModeOperationTests.cs" />
     <Compile Include="Behaviour\Operations\ServiceConnectionOperationTests.cs" />
+    <Compile Include="Behaviour\Operations\SessionSequenceOperationTests.cs" />
     <Compile Include="Behaviour\RuntimeControllerTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>

SafeExamBrowser.Runtime/Behaviour/Operations/ConfigurationOperation.cs

@@ -58,9 +58,9 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 				logger.Info($"Loading configuration from '{uri.AbsolutePath}'...");
 				settings = repository.LoadSettings(uri);
 
-				if (settings.ConfigurationMode == ConfigurationMode.ConfigureClient && UserWantsToAbortStartup())
+				if (settings.ConfigurationMode == ConfigurationMode.ConfigureClient)
 				{
-					Abort = true;
+					Abort = IsConfigurationSufficient();
 					logger.Info($"The user chose to {(Abort ? "abort" : "continue")} the application startup after successful client configuration.");
 				}
 			}
@@ -75,6 +75,7 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 		{
 			// TODO: How will the new settings be retrieved? Uri passed to the repository? If yes, how does the Uri get here?!
 			//		-> IDEA: Use configuration repository as container?
+			//		-> IDEA: Introduce IRepeatParams or alike?
 		}
 
 		public void Revert()
@@ -115,7 +116,7 @@ namespace SafeExamBrowser.Runtime.Behaviour.Operations
 			return isValidUri;
 		}
 
-		private bool UserWantsToAbortStartup()
+		private bool IsConfigurationSufficient()
 		{
 			var message = text.Get(TextKey.MessageBox_ConfigureClientSuccess);
 			var title = text.Get(TextKey.MessageBox_ConfigureClientSuccessTitle);

SafeExamBrowser.Runtime/Communication/RuntimeHost.cs

@@ -7,7 +7,6 @@
  */
 
 using System;
-using System.Threading.Tasks;
 using SafeExamBrowser.Contracts.Communication;
 using SafeExamBrowser.Contracts.Communication.Messages;
 using SafeExamBrowser.Contracts.Communication.Responses;
@@ -39,7 +38,7 @@ namespace SafeExamBrowser.Runtime.Communication
 
 		protected override void OnDisconnect()
 		{
-			Task.Run(() => ClientDisconnected?.Invoke());
+			ClientDisconnected?.Invoke();
 		}
 
 		protected override Response OnReceive(Message message)