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Implementación de un escenario de streaming de conmutación por error

Actualizado: febrero de 2014

Este tutorial explica cómo copiar contenido (blobs) de un recurso a otro con el fin de controlar la redundancia del streaming a petición. Este escenario es útil para los consumidores que desean configurar su red CDN para conmutación por error entre dos centros de datos en caso de que se produzca una interrupción en alguno de nuestros centros de datos.

En este tutorial se usa el SDK de Servicios multimedia de Microsoft Azure, la API REST de Servicios multimedia de Microsoft Azure y el SDK de Almacenamiento de Azure para demostrar las siguientes tareas.

  1. Configurar una cuenta de Media Services en el ”Centro de datos A”.

  2. Cargar un archivo intermedio (mezzanine) en un recurso de origen.

  3. Codificar el recurso en archivos MP4 con velocidad de bits múltiple.

  4. Crear un localizador SAS de solo lectura para que el recurso de origen tenga acceso de lectura al contenedor en la cuenta de Storage asociada al recurso de origen.

  5. Obtener el nombre del contenedor del recurso de origen a partir del localizador SAS de solo lectura creado en el paso anterior. Necesitamos esta información para copiar blobs entre cuentas de almacenamiento (se explica más adelante en el tema).

  6. Crear un localizador de origen para el recurso que se creó con la tarea de codificación.



    Después, para controlar la conmutación por error:



  7. Configurar una cuenta de Media Services en el ”Centro de datos B”.

  8. Crear un recurso de destino vacío en la cuenta de Media Services de destino.

  9. Crear un localizador SAS de escritura para que el recurso de destino vacío tenga acceso de escritura al contenedor en la cuenta de Storage de destino asociada con el recurso de destino.

  10. Usar el SDK de Almacenamiento de Azure para copiar blobs (archivos de recursos) entre la cuenta de almacenamiento de origen del ”Centro de datos A” y la cuenta de almacenamiento de destino del ”Centro de datos B” (estas cuentas de almacenamiento están asociadas con los recursos de interés).

  11. Asociar los blobs (archivos de recursos) que se copiaron en el contenedor de blobs de destino con el recurso de destino.

  12. Crear un localizador de origen para el recurso del ”Centro de datos B” y especificar el Id del localizador que se generó para el recurso en el ”Centro de datos A”.

    Esto proporciona las direcciones URL de streaming donde las rutas de acceso relativas de las direcciones URL son las mismas (solo las URL base son diferentes).

  13. A continuación, para controlar las posibles interrupciones, puede crear una red CDN por encima de estos localizadores de origen.

Debe tenerse en cuenta lo siguiente:

  • La versión actual del SDK de Media Services no admite la creación de un localizador con un identificador de localizador especificado. Para realizar esta tarea, usaremos una API REST de Media Services.

  • La versión actual del SDK de Media Services no admite la generación mediante programación de información de IAssetFile que asociaría un recurso con archivos de recursos. Para realizar esta tarea, usaremos la API REST CreateFileInfos de Media Services.

  • No se admiten recursos cifrados con almacenamiento (AssetCreationOptions.StorageEncrypted) para replicación, ya que la clave de cifrado será diferente en ambas cuentas de Media Services.

  • Si desea sacar partido de los paquetes dinámicos, primero debe obtener al menos una unidad reservada de streaming a petición. Para obtener más información, consulte Paquetes dinámicos.

TipSugerencia
Tenga en cuenta el uso de Media Services Replicator Tool como alternativa para implementar un escenario de streaming de conmutación por error manualmente. Esta herramienta le permite replicar recursos entre dos cuentas de Media Services.

  • Dos cuentas de Media Services en una suscripción a Azure nueva o existente. Consulte el tema sobre la creación de una cuenta de Media Services.

  • Sistemas operativos: Windows 7, Windows 2008 R2 o Windows 8.

  • .NET Framework 4.5 o .NET Framework 4.

  • Visual Studio 2012 o Visual Studio 2010 SP1 (Professional, Premium, Ultimate o Express).

En esta sección, creará y configurará un proyecto de Aplicación de consola de C#.

  1. Use Visual Studio 2012 o Visual Studio 2010 SP1 para crear una nueva solución que contenga el proyecto Aplicación de consola de C#. Escriba HandleRedundancyForOnDemandStreaming en el campo Nombre y haga clic en Aceptar.

  2. Cree la carpeta SupportFiles en mismo nivel que el archivo de proyecto HandleRedundancyForOnDemandStreaming.csproj. Debajo la carpeta SupportFiles, cree las carpetasOutputFiles y MP4Files. Copie un archivo .mp4 en la carpeta MP4Files (en este ejemplo se usa el archivo BigBuckBunny.mp4).

  3. Use Nuget para agregar referencias a DLL relacionadas con Media Services. En el menú principal de Visual Studio, seleccione HERRAMIENTAS -> Administrador de paquetes de biblioteca -> Consola del Administrador de paquetes. En la ventana de la consola, escriba Install-Package windowsazure.mediaservices y presione ENTRAR.

  4. Agregue otras referencias que son necesarias para este proyecto: System.Configuration, System.Runtime.Serialization y System.Web.

  5. Reemplace las instrucciones que se agregaron al archivo Programs.cs de forma predeterminada por las siguientes:

    using System;
    using System.Configuration;
    using System.Globalization;
    using System.IO;
    using System.Net;
    using System.Runtime.Serialization.Json;
    using System.Text;
    using System.Threading;
    using System.Threading.Tasks;
    using System.Web;
    using System.Xml;
    using System.Linq;
    using Microsoft.WindowsAzure;
    using Microsoft.WindowsAzure.MediaServices.Client;
    using Microsoft.WindowsAzure.Storage;
    using Microsoft.WindowsAzure.Storage.Blob;
    using Microsoft.WindowsAzure.Storage.Auth;
    
    
  6. Agregue la sección appSettings al archivo .config y actualice los valores en función de su clave y nombre para Media Services y Almacenamiento.

    <appSettings>
      <add key="MediaServicesAccountNameSource" value="Media-Services-Account-Name-Source"/>
      <add key="MediaServicesAccountKeySource" value="Media-Services-Account-Key-Source"/>
      <add key="MediaServicesStorageAccountNameSource" value="Media-Services-Storage-Account-Name-Source"/>
      <add key="MediaServicesStorageAccountKeySource" value="Media-Services-Storage-Account-Key-Source"/>
      <add key="MediaServicesAccountNameTarget" value="Media-Services-Account-Name-Target" />
      <add key="MediaServicesAccountKeyTarget" value=" Media-Services-Account-Key-Target" />
      <add key="MediaServicesStorageAccountNameTarget" value=" Media-Services-Storage-Account-Name-Target" />
      <add key="MediaServicesStorageAccountKeyTarget" value=" Media-Services-Storage-Account-Key-Target" />
    </appSettings>
    
    

  1. Agregue los siguientes campos a la clase Program.

    // Read values from the App.config file.
    private static readonly string MediaServicesAccountNameSource = ConfigurationManager.AppSettings["MediaServicesAccountNameSource"];
    private static readonly string MediaServicesAccountKeySource = ConfigurationManager.AppSettings["MediaServicesAccountKeySource"];
    private static readonly string StorageNameSource = ConfigurationManager.AppSettings["MediaServicesStorageAccountNameSource"];
    private static readonly string StorageKeySource = ConfigurationManager.AppSettings["MediaServicesStorageAccountKeySource"];
    
    private static readonly string MediaServicesAccountNameTarget = ConfigurationManager.AppSettings["MediaServicesAccountNameTarget"];
    private static readonly string MediaServicesAccountKeyTarget = ConfigurationManager.AppSettings["MediaServicesAccountKeyTarget"];
    private static readonly string StorageNameTarget = ConfigurationManager.AppSettings["MediaServicesStorageAccountNameTarget"];
    private static readonly string StorageKeyTarget = ConfigurationManager.AppSettings["MediaServicesStorageAccountKeyTarget"];
    
    // Base support files path.  Update this field to point to the base path  
    // for the local support files folder that you create. 
    private static readonly string SupportFiles = Path.GetFullPath(@"../..\SupportFiles");
    
    // Paths to support files (within the above base path). 
    private static readonly string SingleInputMp4Path = Path.GetFullPath(SupportFiles + @"\MP4Files\BigBuckBunny.mp4");
    private static readonly string OutputFilesFolder = Path.GetFullPath(SupportFiles + @"\OutputFiles");
    
    // Class-level field used to keep a reference to the service context.
    static private CloudMediaContext _contextSource = null;
    static private CloudMediaContext _contextTarget = null;
    static private MediaServicesCredentials _cachedCredentialsSource = null;
    static private MediaServicesCredentials _cachedCredentialsTarget = null;
    
  2. Reemplace la definición predeterminada del método Main por la siguiente:

    static void Main(string[] args)
    {
        _cachedCredentialsSource = new MediaServicesCredentials(
                        MediaServicesAccountNameSource,
                        MediaServicesAccountKeySource);
    
        _cachedCredentialsTarget = new MediaServicesCredentials(
                        MediaServicesAccountNameTarget,
                        MediaServicesAccountKeyTarget);
    
        // Get server context.    
        _contextSource = new CloudMediaContext(_cachedCredentialsSource);
        _contextTarget = new CloudMediaContext(_cachedCredentialsTarget);
    
    
        IAsset assetSingleFile = CreateAssetAndUploadSingleFile(_contextSource,
                                    AssetCreationOptions.None,
                                    SingleInputMp4Path);
    
        IJob job = CreateEncodingJob(_contextSource, assetSingleFile);
    
        if (job.State != JobState.Error)
        {
            IAsset sourceOutputAsset = job.OutputMediaAssets[0];
            // Get the locator for Smooth Streaming
            var sourceOriginLocator = GetStreamingOriginLocator(_contextSource, sourceOutputAsset);
    
            Console.WriteLine("Locator Id: {0}", sourceOriginLocator.Id);
    
    
            // 1.Create a read-only SAS locator for the source asset to have read access to the container in the source Storage account (associated with the source Media Services account)
            var readSasLocator = GetSasReadLocator(_contextSource, sourceOutputAsset);
    
    
            // 2.Get the container name of the source asset from the read-only SAS locator created in the previous step
            string containerName = (new Uri(readSasLocator.Path)).Segments[1];
    
    
            // 3.Create a target empty asset in the target Media Services account
            var targetAsset = CreateTargetEmptyAsset(_contextTarget, containerName);
    
            // 4.Create a write SAS locator for the target empty asset to have write access to the container in the target Storage account (associated with the target Media Services account)
            ILocator writeSasLocator = CreateSasWriteLocator(_contextTarget, targetAsset);
    
            // Get asset container name.
            string targetContainerName = (new Uri(writeSasLocator.Path)).Segments[1];
    
    
            // 5.Copy the blobs in the source container (source asset) to the target container (target empty asset)
            CopyBlobsFromDifferentStorage(containerName, targetContainerName, StorageNameSource, StorageKeySource, StorageNameTarget, StorageKeyTarget);
    
    
            // 6.Use the CreateFileInfos Media Services REST API to automatically generate all the IAssetFile’s for the target asset. 
            //      This API call is not supported in the current Media Services SDK for .NET. 
            CreateFileInfosForAssetWithRest(_contextTarget, targetAsset, MediaServicesAccountNameTarget, MediaServicesAccountKeyTarget);
    
            // Check if the AssetFiles are now  associated with the asset.
            Console.WriteLine("Asset files assocated with the {0} asset:", targetAsset.Name);
            foreach (var af in targetAsset.AssetFiles)
            {
                Console.WriteLine(af.Name);
            }
    
            // 7.Copy the Origin locator of the source asset to the target asset by using the same Id
            var replicatedLocatorPath = CreateOriginLocatorWithRest(_contextTarget,
                        MediaServicesAccountNameTarget, MediaServicesAccountKeyTarget,
                        sourceOriginLocator.Id, targetAsset.Id);
    
            // Create a full URL to the manifest file. Use this for playback
            // in streaming media clients. 
            string originalUrlForClientStreaming = sourceOriginLocator.Path + GetPrimaryFile(sourceOutputAsset).Name + "/manifest";
    
            Console.WriteLine("Original Locator Path: {0}\n", originalUrlForClientStreaming);
    
            string replicatedUrlForClientStreaming = replicatedLocatorPath + GetPrimaryFile(sourceOutputAsset).Name + "/manifest";
    
            Console.WriteLine("Replicated Locator Path: {0}", replicatedUrlForClientStreaming);
    
            readSasLocator.Delete();
            writeSasLocator.Delete();
    }
    
  3. A continuación se definen las definiciones de método que se llaman desde Main.

    public static IAsset CreateAssetAndUploadSingleFile(CloudMediaContext context,
                                                    AssetCreationOptions assetCreationOptions,
                                                    string singleFilePath)
    {
        // For the AssetCreationOptions you can specify 
        // encryption options.
        //      None:  no encryption. By default, storage encryption is used. If you want to 
        //        create an unencrypted asset, you must set this option.
        //      StorageEncrypted:  storage encryption. Encrypts a clear input file 
        //        before it is uploaded to Azure storage. This is the default if not specified
        //      CommonEncryptionProtected:  for Common Encryption Protected (CENC) files. An 
        //        example is a set of files that are already PlayReady encrypted. 
    
        var assetName = "UploadSingleFile_" + DateTime.UtcNow.ToString();
    
        var asset = context.Assets.Create(assetName, assetCreationOptions);
    
        Console.WriteLine("Asset name: " + asset.Name);
    
        var fileName = Path.GetFileName(singleFilePath);
    
        var assetFile = asset.AssetFiles.Create(fileName);
    
        Console.WriteLine("Created assetFile {0}", assetFile.Name);
    
        Console.WriteLine("Upload {0}", assetFile.Name);
    
        assetFile.Upload(singleFilePath);
        Console.WriteLine("Done uploading of {0}", assetFile.Name);
    
        return asset;
    }
    
    public static IJob CreateEncodingJob(CloudMediaContext context, IAsset asset)
    {
        // Declare a new job.
        IJob job = context.Jobs.Create("My encoding job");
    
        // Get a media processor reference, and pass to it the name of the 
        // processor to use for the specific task.
        IMediaProcessor processor = GetLatestMediaProcessorByName(context,
                                                "Windows Azure Media Encoder");
    
        // Create a task with the encoding details, using a string preset.
        // In this case "H264 Adaptive Bitrate MP4 Set 720p" preset is used.
        ITask task = job.Tasks.AddNew("My encoding task",
            processor,
            "H264 Adaptive Bitrate MP4 Set 720p",
            TaskOptions.ProtectedConfiguration);
    
        // Specify the input asset to be encoded.
        task.InputAssets.Add(asset);
    
        // Add an output asset to contain the results of the job. 
        // This output is specified as AssetCreationOptions.None, which 
        // means the output asset is in the clear (unencrypted). 
        var outputAssetName = "OutputAsset_" + Guid.NewGuid();
        task.OutputAssets.AddNew(outputAssetName,
            AssetCreationOptions.None);
    
        // Use the following event handler to check job progress.  
        job.StateChanged += new
                EventHandler<JobStateChangedEventArgs>(StateChanged);
    
        // Launch the job.
        job.Submit();
    
        // Optionally log job details. This displays basic job details
        // to the console and saves them to a JobDetails-{JobId}.txt file 
        // in your output folder.
        LogJobDetails(context, job.Id);
    
        // Check job execution and wait for job to finish. 
        Task progressJobTask = job.GetExecutionProgressTask(CancellationToken.None);
        progressJobTask.Wait();
    
        // Get an updated job reference.
        job = GetJob(context, job.Id);
    
        // Since we the output asset contains a set of Smooth Streaming files,
        // set the .ism file to be the primary file
        if (job.State != JobState.Error)
            SetPrimaryFile(job.OutputMediaAssets[0]);
    
        return job;
    }
    
    // Create a locator URL to a streaming media asset 
    // on an origin server.
    public static ILocator GetStreamingOriginLocator(CloudMediaContext context, IAsset assetToStream)
    {
        // Get a reference to the streaming manifest file from the  
        // collection of files in the asset. 
        IAssetFile manifestFile = GetPrimaryFile(assetToStream);
    
        // Create a 30-day readonly access policy. 
        IAccessPolicy policy = context.AccessPolicies.Create("Streaming policy",
            TimeSpan.FromDays(30),
            AccessPermissions.Read);
    
        // Create a locator to the streaming content on an origin. 
        ILocator originLocator = context.Locators.CreateLocator(LocatorType.OnDemandOrigin,
            assetToStream,
            policy,
            DateTime.UtcNow.AddMinutes(-5));
    
        // Return the locator. 
        return originLocator;
    }
    
    public static ILocator GetSasReadLocator(CloudMediaContext context, IAsset asset)
    {
        IAccessPolicy accessPolicy = context.AccessPolicies.Create("File Download Policy",
            TimeSpan.FromDays(30), AccessPermissions.Read);
    
        ILocator sasLocator = context.Locators.CreateLocator(LocatorType.Sas,
            asset, accessPolicy);
    
        return sasLocator;
    }
    
    public static ILocator CreateSasWriteLocator(CloudMediaContext context, IAsset asset)
    {
    
        IAccessPolicy writePolicy = context.AccessPolicies.Create("Write Policy",
            TimeSpan.FromDays(30), AccessPermissions.Write);
    
        ILocator sasLocator = context.Locators.CreateLocator(LocatorType.Sas,
            asset, writePolicy);
    
        return sasLocator;
    }
    
    public static IAsset CreateTargetEmptyAsset(CloudMediaContext context, string containerName)
    {
        // Create a new asset.
        IAsset assetToBeProcessed = context.Assets.Create(containerName,
            AssetCreationOptions.None);
    
        return assetToBeProcessed;
    }
    
    public static void CreateFileInfosForAssetWithRest(CloudMediaContext context, IAsset asset, string mediaServicesAccountNameTarget,
        string mediaServicesAccountKeyTarget)
    {
        string apiServer = "";
        string scope = "";
        string acsBaseAddress = "";
    
        string acsToken = GetAcsBearerToken(mediaServicesAccountNameTarget,
                                mediaServicesAccountKeyTarget, scope, acsBaseAddress);
    
        if (!string.IsNullOrEmpty(acsToken))
        {
            CreateFileInfos(apiServer, acsToken, asset.Id);
        }
    }
    
    public static string CreateOriginLocatorWithRest(CloudMediaContext context, string mediaServicesAccountNameTarget,
        string mediaServicesAccountKeyTarget, string locatorIdToReplicate, string targetAssetId)
    {
        //Make sure we are not asking for a duplicate:
        var locator = context.Locators.Where(l => l.Id == locatorIdToReplicate).FirstOrDefault();
        if (locator != null)
            return "";
    
        string locatorNewPath = "";
        string apiServer = "";
        string scope = "";
        string acsBaseAddress = "";
    
        string acsToken = GetAcsBearerToken(mediaServicesAccountNameTarget,
                                mediaServicesAccountKeyTarget, scope, acsBaseAddress);
    
        if (!string.IsNullOrEmpty(acsToken))
        {
            var asset = context.Assets.Where(a => a.Id == targetAssetId).FirstOrDefault();
    
            var accessPolicy = context.AccessPolicies.Create("RestTest", TimeSpan.FromDays(100),
                                                                AccessPermissions.Read);
            if (asset != null)
            {
                string redirectedServiceUri = null;
    
                var xmlResponse = CreateLocator(apiServer, out redirectedServiceUri, acsToken,
                                                            asset.Id, accessPolicy.Id,
                                                            (int)LocatorType.OnDemandOrigin,
                                                            DateTime.UtcNow.AddMinutes(-10), locatorIdToReplicate);
    
                Console.WriteLine("Redirected to: " + redirectedServiceUri);
                if (xmlResponse != null)
                {
                    Console.WriteLine(String.Format("Locator Id: {0}",
                                                    xmlResponse.GetElementsByTagName("Id")[0].InnerText));
                    Console.WriteLine(String.Format("Locator Path: {0}",
                            xmlResponse.GetElementsByTagName("Path")[0].InnerText));
    
    
                    locatorNewPath = xmlResponse.GetElementsByTagName("Path")[0].InnerText;
                }
            }
        }
    
        return locatorNewPath;
    }
    
    
    public static void SetPrimaryFile(IAsset asset)
    {
    
        var ismAssetFiles = asset.AssetFiles.ToList().
                    Where(f => f.Name.EndsWith(".ism", StringComparison.OrdinalIgnoreCase))
                    .ToArray();
    
        if (ismAssetFiles.Count() != 1)
            throw new ArgumentException("The asset should have only one, .ism file");
    
        ismAssetFiles.First().IsPrimary = true;
        ismAssetFiles.First().Update();
    }
    
    public static IAssetFile GetPrimaryFile(IAsset asset)
    {
        var theManifest =
                from f in asset.AssetFiles
                where f.Name.EndsWith(".ism")
                select f;
    
        // Cast the reference to a true IAssetFile type. 
        IAssetFile manifestFile = theManifest.First();
    
        return manifestFile;
    }
    
    public static IAsset RefreshAsset(CloudMediaContext context, IAsset asset)
    {
        asset = context.Assets.Where(a => a.Id == asset.Id).FirstOrDefault();
        return asset;
    }
    
    
    public static void CopyBlobsFromDifferentStorage(string sourceContainerName, string targetContainerName,
                                        string srcAccountName, string srcAccountKey,
                                        string destAccountName, string destAccountKey)
    {
        var srcAccount = new CloudStorageAccount(new StorageCredentials(srcAccountName, srcAccountKey), true);
        var destAccount = new CloudStorageAccount(new StorageCredentials(destAccountName, destAccountKey), true);
    
        var cloudBlobClient = srcAccount.CreateCloudBlobClient();
        var targetBlobClient = destAccount.CreateCloudBlobClient();
    
        var sourceContainer = cloudBlobClient.GetContainerReference(sourceContainerName);
        var targetContainer = targetBlobClient.GetContainerReference(targetContainerName);
        targetContainer.CreateIfNotExists();
    
    
        string blobToken = sourceContainer.GetSharedAccessSignature(new SharedAccessBlobPolicy()
        {
            // Specify the expiration time for the signature.
            SharedAccessExpiryTime = DateTime.Now.AddDays(1),
            // Specify the permissions granted by the signature.
            Permissions = SharedAccessBlobPermissions.Write | SharedAccessBlobPermissions.Read
        });
    
    
        foreach (var sourceBlob in sourceContainer.ListBlobs())
        {
            string fileName = (sourceBlob as ICloudBlob).Name;
            var sourceCloudBlob = sourceContainer.GetBlockBlobReference(fileName);
            sourceCloudBlob.FetchAttributes();
    
            if (sourceCloudBlob.Properties.Length > 0)
            {
                var destinationBlob = targetContainer.GetBlockBlobReference(fileName);
                destinationBlob.StartCopyFromBlob(new Uri(sourceBlob.Uri.AbsoluteUri + blobToken));
    
                while (true)
                {
                    // The StartCopyFromBlob is an async operation, 
                    // so we want to check if the copy operation is completed before proceeding. 
                    // To do that, we call FetchAttributes on the blob and check the CopyStatus. 
                    destinationBlob.FetchAttributes();
                    if (destinationBlob.CopyState.Status != CopyStatus.Pending)
                    {
                        break;
                    }
                    //It's still not completed. So wait for some time.
                    System.Threading.Thread.Sleep(1000);
                }
            }
    
            Console.WriteLine(fileName);
        }
    
        Console.WriteLine("Done copying.");
    }
    private static IMediaProcessor GetLatestMediaProcessorByName(CloudMediaContext context, string mediaProcessorName)
    {
        // The possible strings that can be passed into the 
        // method for the mediaProcessor parameter:
        // Windows Azure Media Encoder
        // Windows Azure Media Packager
        // Windows Azure Media Encryptor
        //   Storage Decryption
    
        var processor = context.MediaProcessors.Where(p => p.Name == mediaProcessorName).
            ToList().OrderBy(p => new Version(p.Version)).LastOrDefault();
    
        if (processor == null)
            throw new ArgumentException(string.Format("Unknown media processor", mediaProcessorName));
    
        return processor;
    }
    
    // This method is a handler for events that track job progress.   
    private static void StateChanged(object sender, JobStateChangedEventArgs e)
    {
        Console.WriteLine("Job state changed event:");
        Console.WriteLine("  Previous state: " + e.PreviousState);
        Console.WriteLine("  Current state: " + e.CurrentState);
    
        switch (e.CurrentState)
        {
            case JobState.Finished:
                Console.WriteLine();
                Console.WriteLine("********************");
                Console.WriteLine("Job is finished.");
                Console.WriteLine("Please wait while local tasks or downloads complete...");
                Console.WriteLine("********************");
                Console.WriteLine();
                Console.WriteLine();
                break;
            case JobState.Canceling:
            case JobState.Queued:
            case JobState.Scheduled:
            case JobState.Processing:
                Console.WriteLine("Please wait...\n");
                break;
            case JobState.Canceled:
            case JobState.Error:
                // Cast sender as a job.
                IJob job = (IJob)sender;
                // Display or log error details as needed.
                LogJobStop(null, job.Id);
                break;
            default:
                break;
        }
    }
    
    private static void LogJobStop(CloudMediaContext context, string jobId)
    {
        StringBuilder builder = new StringBuilder();
        IJob job = GetJob(context, jobId);
    
        builder.AppendLine("\nThe job stopped due to cancellation or an error.");
        builder.AppendLine("***************************");
        builder.AppendLine("Job ID: " + job.Id);
        builder.AppendLine("Job Name: " + job.Name);
        builder.AppendLine("Job State: " + job.State.ToString());
        builder.AppendLine("Job started (server UTC time): " + job.StartTime.ToString());
        // Log job errors if they exist.  
        if (job.State == JobState.Error)
        {
            builder.Append("Error Details: \n");
            foreach (ITask task in job.Tasks)
            {
                foreach (ErrorDetail detail in task.ErrorDetails)
                {
                    builder.AppendLine("  Task Id: " + task.Id);
                    builder.AppendLine("    Error Code: " + detail.Code);
                    builder.AppendLine("    Error Message: " + detail.Message + "\n");
                }
            }
        }
        builder.AppendLine("***************************\n");
        // Write the output to a local file and to the console. The template 
        // for an error output file is:  JobStop-{JobId}.txt
        string outputFile = OutputFilesFolder + @"\JobStop-" + JobIdAsFileName(job.Id) + ".txt";
        WriteToFile(outputFile, builder.ToString());
        Console.Write(builder.ToString());
    }
    
    private static void LogJobDetails(CloudMediaContext context, string jobId)
    {
        StringBuilder builder = new StringBuilder();
        IJob job = GetJob(context, jobId);
    
        builder.AppendLine("\nJob ID: " + job.Id);
        builder.AppendLine("Job Name: " + job.Name);
        builder.AppendLine("Job submitted (client UTC time): " + DateTime.UtcNow.ToString());
    
        // Write the output to a local file and to the console. The template 
        // for an error output file is:  JobDetails-{JobId}.txt
        string outputFile = OutputFilesFolder + @"\JobDetails-" + JobIdAsFileName(job.Id) + ".txt";
        WriteToFile(outputFile, builder.ToString());
        Console.Write(builder.ToString());
    }
    
    // Replace ":" with "_" in Job id values so they can 
    // be used as log file names.  
    private static string JobIdAsFileName(string jobID)
    {
        return jobID.Replace(":", "_");
    }
    
    // Write method output to the output files folder.
    private static void WriteToFile(string outFilePath, string fileContent)
    {
        StreamWriter sr = File.CreateText(outFilePath);
        sr.WriteLine(fileContent);
        sr.Close();
    }
    
    private static IJob GetJob(CloudMediaContext context, string jobId)
    {
        // Use a Linq select query to get an updated 
        // reference by Id. 
        var jobInstance =
            from j in context.Jobs
            where j.Id == jobId
            select j;
    
        // Return the job reference as an Ijob. 
        IJob job = jobInstance.FirstOrDefault();
    
        return job;
    }
    
    private static IAsset GetAsset(CloudMediaContext context, string assetId)
    {
        // Use a LINQ Select query to get an asset.
        var assetInstance =
            from a in context.Assets
            where a.Id == assetId
            select a;
    
        // Reference the asset as an IAsset.
        IAsset asset = assetInstance.FirstOrDefault();
    
        return asset;
    }
    
    public static void DeleteAllAssets(CloudMediaContext context)
    {
        // Loop through and delete all assets.
        foreach (IAsset asset in context.Assets)
        {
            DeleteLocatorsForAsset(context, asset);
    
            asset.Delete();
        }
    }
    
    public static void DeleteLocatorsForAsset(CloudMediaContext context, IAsset asset)
    {
        string assetId = asset.Id;
        var locators = from a in context.Locators
                        where a.AssetId == assetId
                        select a;
        foreach (var locator in locators)
        {
            Console.WriteLine("Deleting locator {0} for asset {1}", locator.Path, assetId);
    
            locator.Delete();
        }
    }
    
    public static void DeleteAccessPolicy(CloudMediaContext context, string existingPolicyId)
    {
        // To delete a specific access policy, get a reference to the policy.  
        // based on the policy Id passed to the method.
        var policyInstance =
                from p in context.AccessPolicies
                where p.Id == existingPolicyId
                select p;
    
        IAccessPolicy policy = policyInstance.FirstOrDefault();
    
        policy.Delete();
    
    }
    
    //////////////////////////////////////////////////////
    /// The following methods use REST calls.
    //////////////////////////////////////////////////////
    
    public static string GetAcsBearerToken(string clientId, string clientSecret, string scope, string accessControlServiceUri)
    {
        if (string.IsNullOrEmpty(clientId))
            throw new ArgumentNullException("clientId");
    
        if (string.IsNullOrEmpty(clientSecret))
            throw new ArgumentNullException("clientSecret");
    
        if (string.IsNullOrEmpty(scope))
        {
            scope = "urn:WindowsAzureMediaServices";
        }
        else if (!scope.ToLower().StartsWith("urn:"))
        {
            scope = "urn:" + scope;
        }
    
        if (string.IsNullOrEmpty(accessControlServiceUri))
        {
            accessControlServiceUri = "https://wamsprodglobal001acs.accesscontrol.windows.net/v2/OAuth2-13";
        }
        else if (!accessControlServiceUri.ToLower().EndsWith("/v2/oauth2-13"))
        {
            accessControlServiceUri = accessControlServiceUri.TrimEnd('/') + "/v2/OAuth2-13";
        }
    
        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(accessControlServiceUri);
        request.Method = "POST";
        request.ContentType = "application/x-www-form-urlencoded";
        request.KeepAlive = true;
        string acsBearerToken = null;
    
        var requestBytes = Encoding.ASCII.GetBytes("grant_type=client_credentials&client_id=" +
            clientId + "&client_secret=" + HttpUtility.UrlEncode(clientSecret) +
            "&scope=" + HttpUtility.UrlEncode(scope));
        request.ContentLength = requestBytes.Length;
    
        var requestStream = request.GetRequestStream();
        requestStream.Write(requestBytes, 0, requestBytes.Length);
        requestStream.Close();
    
        var response = (HttpWebResponse)request.GetResponse();
    
        if (response.StatusCode == HttpStatusCode.OK)
        {
            using (Stream responseStream = response.GetResponseStream())
            {
                using (StreamReader stream = new StreamReader(responseStream))
                {
                    string responseString = stream.ReadToEnd();
                    var reader = JsonReaderWriterFactory.CreateJsonReader(Encoding.UTF8.GetBytes(responseString),
                        new XmlDictionaryReaderQuotas());
    
                    while (reader.Read())
                    {
                        if ((reader.Name == "access_token") && (reader.NodeType == XmlNodeType.Element))
                        {
                            if (reader.Read())
                            {
                                acsBearerToken = reader.Value;
                                break;
                            }
                        }
                    }
                }
            }
        }
    
        return acsBearerToken;
    }
    
    public static XmlDocument CreateLocator(string mediaServicesApiServerUri,
                                            out string redirectedMediaServicesApiServerUri,
                                            string acsBearerToken, string assetId,
                                            string accessPolicyId, int locatorType,
                                            DateTime startTime, string locatorIdToReplicate = null,
                                            bool autoRedirect = true)
    {
        if (string.IsNullOrEmpty(mediaServicesApiServerUri))
        {
            mediaServicesApiServerUri = "https://media.windows.net/api/";
        }
        if (!mediaServicesApiServerUri.EndsWith("/"))
            mediaServicesApiServerUri = mediaServicesApiServerUri + "/";
    
        if (string.IsNullOrEmpty(acsBearerToken)) throw new ArgumentNullException("acsBearerToken");
        if (string.IsNullOrEmpty(assetId)) throw new ArgumentNullException("assetId");
        if (string.IsNullOrEmpty(accessPolicyId)) throw new ArgumentNullException("accessPolicyId");
    
        redirectedMediaServicesApiServerUri = null;
        XmlDocument xmlResponse = null;
    
        StringBuilder sb = new StringBuilder();
        sb.Append("{ \"AssetId\" : \"" + assetId + "\"");
        sb.Append(", \"AccessPolicyId\" : \"" + accessPolicyId + "\"");
        sb.Append(", \"Type\" : \"" + locatorType + "\"");
        if (startTime != DateTime.MinValue)
            sb.Append(", \"StartTime\" : \"" + startTime.ToString("G", CultureInfo.CreateSpecificCulture("en-us")) + "\"");
        if (!string.IsNullOrEmpty(locatorIdToReplicate))
            sb.Append(", \"Id\" : \"" + locatorIdToReplicate + "\"");
        sb.Append("}");
    
        string requestbody = sb.ToString();
    
        try
        {
            var request = GenerateRequest("POST", mediaServicesApiServerUri, "Locators",
                null, acsBearerToken, requestbody);
            var response = (HttpWebResponse)request.GetResponse();
    
            switch (response.StatusCode)
            {
                case HttpStatusCode.MovedPermanently:
                    //Recurse once with the mediaServicesApiServerUri redirect Location:
                    if (autoRedirect)
                    {
                        redirectedMediaServicesApiServerUri = response.Headers["Location"];
                        string secondRedirection = null;
                        xmlResponse = CreateLocator(redirectedMediaServicesApiServerUri,
                                                    out secondRedirection, acsBearerToken,
                                                    assetId, accessPolicyId, locatorType,
                                                    startTime, locatorIdToReplicate, false);
                    }
                    else
                    {
                        Console.WriteLine("Redirection to {0} failed.",
                            mediaServicesApiServerUri);
                        return null;
                    }
                    break;
                case HttpStatusCode.Created:
                    using (Stream responseStream = response.GetResponseStream())
                    {
                        using (StreamReader stream = new StreamReader(responseStream))
                        {
                            string responseString = stream.ReadToEnd();
                            var reader = JsonReaderWriterFactory.
                                CreateJsonReader(Encoding.UTF8.GetBytes(responseString),
                                    new XmlDictionaryReaderQuotas());
    
                            xmlResponse = new XmlDocument();
                            reader.Read();
                            xmlResponse.LoadXml(reader.ReadInnerXml());
                        }
                    }
                    break;
    
                default:
                    Console.WriteLine(response.StatusDescription);
                    break;
            }
        }
        catch (WebException ex)
        {
            Console.WriteLine(ex.Message);
        }
    
        return xmlResponse;
    }
    
    public static void CreateFileInfos(string mediaServicesApiServerUri,
                                string acsBearerToken,
                                string assetId
                                )
    {
        if (String.IsNullOrEmpty(mediaServicesApiServerUri))
        {
            mediaServicesApiServerUri = "https://media.windows.net/api/";
        }
        if (!mediaServicesApiServerUri.EndsWith("/"))
            mediaServicesApiServerUri = mediaServicesApiServerUri + "/";
    
        if (String.IsNullOrEmpty(acsBearerToken)) throw new ArgumentNullException("acsBearerToken");
        if (String.IsNullOrEmpty(assetId)) throw new ArgumentNullException("assetId");
    
    
        string id = assetId.Replace(":", "%");
    
        UriBuilder builder = new UriBuilder(mediaServicesApiServerUri);
        builder.Path = Path.Combine(builder.Path, "CreateFileInfos");
        builder.Query = String.Format(CultureInfo.InvariantCulture, "assetid='{0}'", assetId);
    
        try
        {
            var request = GenerateRequest("GET", mediaServicesApiServerUri, "CreateFileInfos",
                String.Format(CultureInfo.InvariantCulture, "assetid='{0}'", assetId), acsBearerToken, null);
    
            using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
            {
                if (response.StatusCode == HttpStatusCode.MovedPermanently)
                {
                    string redirectedMediaServicesApiUrl = response.Headers["Location"];
    
                    CreateFileInfos(redirectedMediaServicesApiUrl, acsBearerToken, assetId);
                }
                else if ((response.StatusCode != HttpStatusCode.OK) &&
                    (response.StatusCode != HttpStatusCode.Accepted) &&
                    (response.StatusCode != HttpStatusCode.Created) &&
                    (response.StatusCode != HttpStatusCode.NoContent))
                {
                    // TODO: Throw a more specific exception.
                    throw new Exception("Invalid response received ");
                }
            }
        }
        catch (WebException ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
    
    
    private static HttpWebRequest GenerateRequest(string verb,
                                                    string mediaServicesApiServerUri,
                                                    string resourcePath, string query,
                                                    string acsBearerToken, string requestbody)
    {
        var uriBuilder = new UriBuilder(mediaServicesApiServerUri);
        uriBuilder.Path += resourcePath;
        if (query != null)
        {
            uriBuilder.Query = query;
        }
        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(uriBuilder.Uri);
        request.AllowAutoRedirect = false; //We manage our own redirects.
        request.Method = verb;
    
        if (resourcePath == "$metadata")
            request.MediaType = "application/xml";
        else
        {
            request.ContentType = "application/json;odata=verbose";
            request.Accept = "application/json;odata=verbose";
        }
    
        request.Headers.Add("DataServiceVersion", "3.0");
        request.Headers.Add("MaxDataServiceVersion", "3.0");
        request.Headers.Add("x-ms-version", "2.1");
        request.Headers.Add(HttpRequestHeader.Authorization, "Bearer " + acsBearerToken);
    
        if (requestbody != null)
        {
            var requestBytes = Encoding.ASCII.GetBytes(requestbody);
            request.ContentLength = requestBytes.Length;
    
            var requestStream = request.GetRequestStream();
            requestStream.Write(requestBytes, 0, requestBytes.Length);
            requestStream.Close();
        }
        else
        {
            request.ContentLength = 0;
        }
        return request;
    }
    
    
    

Ahora puede usar un administrador de tráfico para redirigir solicitudes entre dos centros de datos y, por lo tanto, aplicar la conmutación por error en caso de interrupción.

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