public override void Run()
{
try
{
Trace.TraceInformation("PoP.ServiceTier entry point called");
var queueValetKeyUrl = ConfigurationManager.AppSettings["MediaIngestionQueueValetKeyUrl"];
var queueValet = new QueueValet(queueValetKeyUrl);
var blobValetKeyUrl = ConfigurationManager.AppSettings["MediaStorageValetKeyUrl"];
var blobValet = new BlobValet(blobValetKeyUrl);
InitStorage(queueValet, blobValet);
while (true)
{
Trace.TraceInformation("Working on the next iteration from PoP.ServiceTier.Run");
NewMediaProcessor.ProcessNextMediaMessage(queueValet, blobValet);
Thread.Sleep(TimeSpan.FromSeconds(2));
}
}
catch (Exception)
{
Trace.TraceError("PoP.ServiceTier.Run has detected an uncaught exception was thrown - this should never happen", "Error");
throw;
}
}
private static void InitStorage(QueueValet queueValet, BlobValet blobValet)
{
queueValet.CreateQueue("media-ingestion");
blobValet.CreateBlobContainer("popmedia", true);
var container = blobValet.CreateBlobContainer("popuploads", false);
string sasPolicy = BlobValet.CreateBlobSASPolicy(
container,
"untrusted-uploader",
DateTime.UtcNow.AddYears(10),
new SharedAccessBlobPermissions[] { SharedAccessBlobPermissions.Write }
);
}
/// <summary>
/// Upload the blob and then (if nothing went wrong) drop a message on the queue announcing the blob
/// </summary>
/// <param name="queueValet"></param>
/// <param name="mediaByteStream">Might be from File Upload via web page</param>
/// <param name="origFilename"></param>
/// <param name="mimeType"></param>
/// <param name="byteCount">Count of bytes in the stream. Not used at this time. May be used in future to optimize the upload to blob storage, for telemetry, or to block uploads over a certain size.</param>
/// <param name="destinationUrl"></param>
/// <param name="blobValet"></param>
public static void CaptureUploadedMedia(BlobValet blobValet, QueueValet queueValet, Stream mediaByteStream,
string origFilename,
string mimeType, int byteCount, string destinationUrl)
{
try
{
// TODO: obviate MediaStorageUrlFile.ExtTemplate by basing on MediaStorageValetKeyUrl value --- value="http://127.0.0.1:10000/devstoreaccount1/popmedia/{0}{1}" & "http://127.0.0.1:10000/devstoreaccount1/popmedia?sr=c&si=open-wide-container-access-policy&sig=X0yGw1Ydmu%2BCwk%2FTY7nj5HFgzv%2BIYg%2Bun%2BHQhNMmThk%3D"
#if false
var destinationUrl =
String.Format(ConfigurationManager.AppSettings["MediaStorageUrlFile.ExtTemplate"],
Guid.NewGuid(),
new FileInfo(origFilename).Extension
);
var valetKeyUrl = ConfigurationManager.AppSettings["MediaStorageValetKeyUrl"];
// if that worked, notify via queue
var mediaIngestionQueueValetKeyUrl = ConfigurationManager.AppSettings["MediaIngestionQueueValetKeyUrl"];
#endif
blobValet.UploadStream(new Uri(destinationUrl), mediaByteStream, mimeType); // TODO: at moment is sync (not async) to avoid race condition mentioned below
var info = new MediaUploadModel
{
BlobUrl = destinationUrl,
Username = "******"
};
// prep an arbitrary object to send on the queue, not just a string (not rich enough for our use case)
var queueMessage = new CloudQueueMessage(ByteArraySerializer<MediaUploadModel>.Serialize(info));
// TODO: race condition when both uploading a BLOB and posting the Queue message - the queue message processing
// TODO: ... can begin before the blob upload is complete -- need to sync these
// TODO: ... BUT! for now it will still FUNCTION CORRECTLY (if inefficiently) due to Queue-Centric Workflow Pattern retries IF not determined to be a Poison Message
// There is no real need for a 50ms delay before the message can appear in queue, but just showing how to do it.
// Technique is sometimes useful when there's a reason to delay its processing. You could use it to implement a
// scheduler, for example. In the case of PoP, there are no obvious use cases. A made-up use case might be if PoP
// introduced a way to make photos show up in the future allowing the user uploading them to indicate PoP should
// delay processing for, say, up to 24 hours, and let the user optionally specify a delay within that range.
queueValet.AddMessage(queueMessage, initialVisibilityDelay: TimeSpan.FromMilliseconds(50));
}
catch (StorageException ex)
{
System.Diagnostics.Trace.TraceError("Exception thrown in BlobExtensions.UploadFile: " + ex);
throw;
}
}
public static void ProcessNextMediaMessage(QueueValet queueValet, BlobValet blobValet)
{
try
{
var msg = queueValet.GetMessage(TimeSpan.FromMinutes(5));
if (msg != null)
{
if (msg.DequeueCount <= 1)
Trace.TraceInformation("DequeueCount = {0}", msg.DequeueCount);
else
Trace.TraceWarning("DequeueCount = {0}", msg.DequeueCount);
//TODO: if (msg.DequeueCount > 5) return;
// Is it a photo or video? -- only photo supported for now... so assume that
// (alternatively, might have a photo queue and a video queue)
var mediaUploadInfo = ByteArraySerializer<MediaUploadModel>.Deserialize(msg.AsBytes);
var uploadedPhotoUrl = mediaUploadInfo.BlobUrl;
var username = mediaUploadInfo.Username;
ProcessNextPhotoUpload(username, uploadedPhotoUrl, blobValet);
queueValet.DeleteMessage(msg);
// TODO: Ensure proper Poison Message Handling
}
}
catch (Exception ex)
{
// this method CANNOT throw an exception - that's bad manners - even if there is a failure
// SEE: Queue-Centric Workflow Pattern (chapter 3) plus Poison Message and Reliable Queue concepts
// SEE: Strong Exception Guarantee http://en.wikipedia.org/wiki/Exception_safety
// or relate to the NoFail Guaranteed from http://c2.com/cgi/wiki?ExceptionGuarantee
var debugMsg =
String.Format("Exception in PoP.ServiceTier.NewMediaProcessor.ProcessNextMediaMessage [{0}]\n[{1}]",
ex.GetBaseException(), ex);
Trace.TraceError(debugMsg);
}
}
public ActionResult Upload(IEnumerable<HttpPostedFileBase> files)
{
var fileList = String.Empty;
var firstFile = true;
foreach (var file in files.Where(file => file != null && file.ContentLength > 0))
{
Contract.Assert(file.FileName == Path.GetFileName(file.FileName)); // browsers should not send path info - but synthetic test could
var fileExtension = Path.GetExtension(file.FileName);
if (!String.IsNullOrWhiteSpace(fileExtension)) fileExtension = fileExtension.ToLower();
var destinationUrl = String.Format(ConfigurationManager.AppSettings["MediaStorageUrlFile.ExtTemplate"], Guid.NewGuid(), fileExtension);
var blobValetKeyUrl = ConfigurationManager.AppSettings["MediaStorageValetKeyUrl"];
var queueValetKeyUrl = ConfigurationManager.AppSettings["MediaIngestionQueueValetKeyUrl"];
var blobValet = new BlobValet(blobValetKeyUrl);
var queueValet = new QueueValet(queueValetKeyUrl);
MediaIngester.CaptureUploadedMedia(blobValet, queueValet, file.InputStream, file.FileName, file.ContentType, file.ContentLength, destinationUrl);
if (!firstFile) fileList += ", ";
fileList += file.FileName;
firstFile = false;
}
if (String.IsNullOrWhiteSpace(fileList))
{
return RedirectToAction("Upload");
}
else
{
var message = String.Format("Upload successful for: {0}", fileList);
return RedirectToAction("Upload", new { msg = message });
}
}