public static void GenerateThumbnail(
[QueueTrigger("thumbnailrequest")] BlobInformation blobInfo,
[Blob("images/{BlobName}", FileAccess.Read)] Stream input,
[Blob("images/{BlobNameWithoutExtension}_thumbnail.jpg")] CloudBlockBlob outputBlob)
{
using (Stream output = outputBlob.OpenWrite())
{
ConvertImageToThumbnailJPG(input, output);
outputBlob.Properties.ContentType = "image/jpeg";
}
// Entity Framework context class is not thread-safe, so it must
// be instantiated and disposed within the function.
ContosoAdsContext tableContext = new ContosoAdsContext();
var id = blobInfo.AdId;
Ad ad = tableContext.GetAd(id);
if (ad == null)
{
throw new Exception(String.Format("AdId {0} not found, can't create thumbnail", id.ToString()));
}
ad.ThumbnailURL = outputBlob.Uri.ToString();
TableOperation updateOperation = TableOperation.Replace(ad);
// Execute the operation.
tableContext.Table.Execute(updateOperation);
}
// A production app would also include an OnStop override to provide for
// graceful shut-downs of worker-role VMs. See
// http://azure.microsoft.com/en-us/documentation/articles/cloud-services-dotnet-multi-tier-app-storage-3-web-role/#restarts
public override bool OnStart()
{
// Set the maximum number of concurrent connections.
ServicePointManager.DefaultConnectionLimit = 12;
// Read database connection string and open database.
var dbConnString = CloudConfigurationManager.GetSetting("ContosoAdsDbConnectionString");
db = new ContosoAdsContext(dbConnString);
// Open storage account using credentials from .cscfg file.
var storageAccount = CloudStorageAccount.Parse
(RoleEnvironment.GetConfigurationSettingValue("StorageConnectionString"));
Trace.TraceInformation("Creating images blob container");
var blobClient = storageAccount.CreateCloudBlobClient();
imagesBlobContainer = blobClient.GetContainerReference("images");
if (imagesBlobContainer.CreateIfNotExists())
{
// Enable public access on the newly created "images" container.
imagesBlobContainer.SetPermissions(
new BlobContainerPermissions
{
PublicAccess = BlobContainerPublicAccessType.Blob
});
}
Trace.TraceInformation("Creating images queue");
CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();
imagesQueue = queueClient.GetQueueReference("images");
imagesQueue.CreateIfNotExists();
Trace.TraceInformation("Storage initialized");
return base.OnStart();
}
