Retry logic in the Media Services SDK for .NET

  • Article

When working with Microsoft Azure services, transient faults can occur. If a transient fault occurs, in most cases, after a few retries the operation succeeds. The Media Services SDK for .NET implements the retry logic to handle transient faults associated with exceptions and errors that are caused by web requests, executing queries, saving changes, and storage operations. By default, the Media Services SDK for .NET executes four retries before re-throwing the exception to your application. The code in your application must then handle this exception properly.

The following is a brief guideline of Web Request, Storage, Query, and SaveChanges policies:

  • The Storage policy is used for blob storage operations (uploads or download of asset files).

  • The Web Request policy is used for generic web requests (for example, for getting an authentication token and resolving the users cluster endpoint).

  • The Query policy is used for querying entities from REST (for example, mediaContext.Assets.Where(…)).

  • The SaveChanges policy is used for doing anything that changes data within the service (for example, creating an entity updating an entity, calling a service function for an operation).

    This topic lists exception types and error codes that are handled by the Media Services SDK for .NET retry logic.

Exception types

The following table describes exceptions that the Media Services SDK for .NET handles or does not handle for some operations that may cause transient faults.

Exception Web Request Storage Query SaveChanges
WebException
For more information, see the WebException status codes section.		 Yes Yes Yes Yes
DataServiceClientException
For more information, see HTTP error status codes.		 No Yes Yes Yes
DataServiceQueryException
For more information, see HTTP error status codes.		 No Yes Yes Yes
DataServiceRequestException
For more information, see HTTP error status codes.		 No Yes Yes Yes
DataServiceTransportException No No Yes Yes
TimeoutException Yes Yes Yes No
SocketException Yes Yes Yes Yes
StorageException No Yes No No
IOException No Yes No No

WebException status codes

The following table shows for which WebException error codes the retry logic is implemented. The WebExceptionStatus enumeration defines the status codes.

Status Web Request Storage Query SaveChanges
ConnectFailure Yes Yes Yes Yes
NameResolutionFailure Yes Yes Yes Yes
ProxyNameResolutionFailure Yes Yes Yes Yes
SendFailure Yes Yes Yes Yes
PipelineFailure Yes Yes Yes No
ConnectionClosed Yes Yes Yes No
KeepAliveFailure Yes Yes Yes No
UnknownError Yes Yes Yes No
ReceiveFailure Yes Yes Yes No
RequestCanceled Yes Yes Yes No
Timeout Yes Yes Yes No
ProtocolError
The retry on ProtocolError is controlled by the HTTP status code handling. For more information, see HTTP error status codes.		 Yes Yes Yes Yes

HTTP error status codes

When Query and SaveChanges operations throw DataServiceClientException, DataServiceQueryException, or DataServiceQueryException, the HTTP error status code is returned in the StatusCode property. The following table shows for which error codes the retry logic is implemented.

Status Web Request Storage Query SaveChanges
401 No Yes No No
403 No Yes
Handling retries with longer waits.		 No No
408 Yes Yes Yes Yes
429 Yes Yes Yes Yes
500 Yes Yes Yes No
502 Yes Yes Yes No
503 Yes Yes Yes Yes
504 Yes Yes Yes No

If you want to take a look at the actual implementation of the Media Services SDK for .NET retry logic, see azure-sdk-for-media-services.