317 lines
8.1 KiB
C#
317 lines
8.1 KiB
C#
/*
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* Copyright (c) 2025 ETH Zürich, IT Services
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using SafeExamBrowser.Configuration.Contracts;
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using SafeExamBrowser.Core.Contracts.OperationModel;
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using SafeExamBrowser.Core.Contracts.OperationModel.Events;
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using SafeExamBrowser.I18n.Contracts;
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using SafeExamBrowser.Server.Contracts;
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using SafeExamBrowser.Server.Contracts.Data;
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using SafeExamBrowser.Settings;
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using SafeExamBrowser.SystemComponents.Contracts;
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using SafeExamBrowser.UserInterface.Contracts;
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namespace SafeExamBrowser.Runtime.Operations.Session
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{
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internal class ServerOperation : ConfigurationBaseOperation
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{
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private readonly IFileSystem fileSystem;
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private readonly IServerProxy server;
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public override event StatusChangedEventHandler StatusChanged;
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public ServerOperation(
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Dependencies dependencies,
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IFileSystem fileSystem,
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IConfigurationRepository repository,
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IServerProxy server,
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IUserInterfaceFactory uiFactory) : base(dependencies, repository, uiFactory)
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{
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this.fileSystem = fileSystem;
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this.server = server;
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}
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public override OperationResult Perform()
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{
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var result = OperationResult.Success;
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if (Context.Next.Settings.SessionMode == SessionMode.Server)
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{
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var browserExamKey = default(string);
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var exam = default(Exam);
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var exams = default(IEnumerable<Exam>);
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var uri = default(Uri);
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Logger.Info("Initializing server...");
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StatusChanged?.Invoke(TextKey.OperationStatus_InitializeServer);
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server.Initialize(Context.Next.Settings.Server);
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var (abort, fallback, success) = TryPerformWithFallback(() => server.Connect());
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if (success)
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{
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(abort, fallback, success) = TryPerformWithFallback(() => server.GetAvailableExams(Context.Next.Settings.Server.ExamId), out exams);
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}
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if (success)
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{
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success = TrySelectExam(exams, out exam);
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}
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if (success)
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{
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(abort, fallback, success) = TryPerformWithFallback(() => server.GetConfigurationFor(exam), out uri);
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}
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if (success)
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{
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result = TryLoadServerSettings(exam, uri);
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}
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if (success && result == OperationResult.Success)
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{
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(abort, fallback, success) = TryPerformWithFallback(() => server.SendSelectedExam(exam), out browserExamKey);
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}
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if (browserExamKey != default)
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{
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Context.Next.Settings.Browser.CustomBrowserExamKey = browserExamKey;
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}
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if (abort)
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{
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result = OperationResult.Aborted;
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Logger.Info("The user aborted the server operation.");
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}
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if (fallback)
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{
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Context.Next.Settings.SessionMode = SessionMode.Normal;
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result = OperationResult.Success;
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Logger.Info("The user chose to fallback and start a normal session.");
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}
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if (result == OperationResult.Success)
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{
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Logger.Info("Successfully initialized server.");
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}
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else if (result == OperationResult.Failed)
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{
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Logger.Error("Failed to initialize server!");
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}
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}
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return result;
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}
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public override OperationResult Repeat()
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{
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var result = OperationResult.Success;
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if (Context.Current.Settings.SessionMode == SessionMode.Server && Context.Next.Settings.SessionMode == SessionMode.Server)
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{
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result = Revert();
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if (result == OperationResult.Success)
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{
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result = Perform();
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}
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else
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{
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Logger.Error($"Cannot start new server session due to failed finalization of current server session! Terminating...");
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}
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}
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else if (Context.Current.Settings.SessionMode == SessionMode.Server)
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{
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result = Revert();
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}
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else if (Context.Next.Settings.SessionMode == SessionMode.Server)
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{
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result = Perform();
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}
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return result;
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}
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public override OperationResult Revert()
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{
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var result = OperationResult.Success;
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if (Context.Current?.Settings.SessionMode == SessionMode.Server || Context.Next?.Settings.SessionMode == SessionMode.Server)
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{
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Logger.Info("Finalizing server...");
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StatusChanged?.Invoke(TextKey.OperationStatus_FinalizeServer);
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var disconnect = server.Disconnect();
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if (disconnect.Success)
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{
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result = OperationResult.Success;
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Logger.Info("Successfully finalized server.");
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}
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else
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{
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result = OperationResult.Failed;
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Logger.Error("Failed to finalize server!");
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}
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}
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return result;
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}
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private OperationResult TryLoadServerSettings(Exam exam, Uri uri)
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{
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var info = server.GetConnectionInfo();
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var result = OperationResult.Failed;
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var status = TryLoadSettings(uri, UriSource.Server, out _, out var settings);
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fileSystem.Delete(uri.LocalPath);
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if (status == LoadStatus.Success)
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{
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var browserSettings = Context.Next.Settings.Browser;
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var invigilationSettings = settings.Server.Invigilation;
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var serverSettings = Context.Next.Settings.Server;
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Context.Next.AppConfig.ServerApi = info.Api;
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Context.Next.AppConfig.ServerConnectionToken = info.ConnectionToken;
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Context.Next.AppConfig.ServerExamId = exam.Id;
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Context.Next.AppConfig.ServerOauth2Token = info.Oauth2Token;
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Context.Next.Settings = settings;
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Context.Next.Settings.Browser.StartUrl = exam.Url;
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Context.Next.Settings.Browser.StartUrlQuery = browserSettings.StartUrlQuery;
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Context.Next.Settings.Server = serverSettings;
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Context.Next.Settings.Server.Invigilation = invigilationSettings;
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Context.Next.Settings.SessionMode = SessionMode.Server;
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result = OperationResult.Success;
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}
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return result;
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}
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private (bool abort, bool fallback, bool success) TryPerformWithFallback(Func<ServerResponse> request)
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{
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var abort = false;
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var fallback = false;
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var success = false;
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while (!success)
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{
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var response = request();
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success = response.Success;
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if (!success && !Retry(response.Message, out abort, out fallback))
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{
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break;
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}
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}
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return (abort, fallback, success);
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}
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private (bool abort, bool fallback, bool success) TryPerformWithFallback<T>(Func<ServerResponse<T>> request, out T value)
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{
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var abort = false;
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var fallback = false;
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var success = false;
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value = default;
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while (!success)
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{
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var response = request();
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success = response.Success;
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value = response.Value;
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if (!success && !Retry(response.Message, out abort, out fallback))
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{
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break;
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}
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}
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return (abort, fallback, success);
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}
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private bool Retry(string message, out bool abort, out bool fallback)
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{
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AskForServerFailureAction(message, out abort, out fallback, out var retry);
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if (retry)
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{
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Logger.Debug("The user chose to retry the current server request.");
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}
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return retry;
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}
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private void AskForServerFailureAction(string message, out bool abort, out bool fallback, out bool retry)
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{
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var showFallback = Context.Next.Settings.Server.PerformFallback;
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if (ClientBridge.IsRequired())
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{
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ClientBridge.TryAskForServerFailureAction(message, showFallback, out abort, out fallback, out retry);
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}
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else
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{
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var dialog = uiFactory.CreateServerFailureDialog(message, showFallback);
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var result = dialog.Show(RuntimeWindow);
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abort = result.Abort;
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fallback = result.Fallback;
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retry = result.Retry;
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}
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}
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private bool TrySelectExam(IEnumerable<Exam> exams, out Exam exam)
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{
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var success = true;
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if (string.IsNullOrWhiteSpace(Context.Next.Settings.Server.ExamId))
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{
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success = TryAskForExamSelection(exams, out exam);
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}
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else
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{
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exam = exams.First();
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Logger.Info("Automatically selected exam as defined in configuration.");
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}
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return success;
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}
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private bool TryAskForExamSelection(IEnumerable<Exam> exams, out Exam exam)
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{
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var success = false;
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if (ClientBridge.IsRequired())
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{
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success = ClientBridge.TryAskForExamSelection(exams, out exam);
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}
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else
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{
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var dialog = uiFactory.CreateExamSelectionDialog(exams);
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var result = dialog.Show(RuntimeWindow);
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exam = result.SelectedExam;
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success = result.Success;
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}
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return success;
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}
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}
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}
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