Windows Azure Storage Release - Introducing CORS, JSON, Minute Metrics, and More

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We are excited to announce the availability of a new storage version 2013-08-15 that provides various new functionalities across Windows Azure Blobs, Tables and Queues. With this version, we are adding the following major features:

1. CORS (Cross Origin Resource Sharing): Windows Azure Blobs, Tables and Queues now support CORS to enable users to access/manipulate resources from within the browser serving a web page in a different domain than the resource being accessed. CORS is an opt-in model which users can turn on using Set/Get Service Properties. Windows Azure Storage supports both CORS preflight OPTIONS request and actual CORS requests. Please see https://msdn.microsoft.com/en-us/library/windowsazure/dn535601.aspx for more information.

2. JSON ( JavaScript Object Notation) : Windows Azure Tables now supports OData 3.0’s JSON format. The JSON format enables efficient wire transfer as it eliminates transferring predictable parts of the payload which are mandatory in AtomPub.

JSON is supported in 3 forms:

  • No Metadata – This format is the most efficient transfer which is useful when the client is aware on how to interpret the data type for custom properties.
  • Minimal Metadata – This format contains data type information for custom properties of certain types that cannot be implicitly interpreted. This is useful for query when the client is unaware of the data types such as general tools or Azure Table browsers.
  • Full metadata – This format is useful for generic OData readers that requires type definition for even system properties and requires OData information like edit link, id, etc.

More information about JSON for Windows Azure Tables can be found at https://msdn.microsoft.com/en-us/library/windowsazure/dn535600.aspx

3. Minute Metrics in Windows Azure Storage Analytics: Up till now, Windows Azure Storage supported hourly aggregates of metrics, which is very useful in monitoring service availability, errors, ingress, egress, API usage, access patterns and to improve client applications and we had blogged about it here. In this new 2013-08-15 version, we are introducing Minute Metrics where data is aggregated at a minute level and typically available within five minutes. Minute level aggregates allow users to monitor client applications in a more real time manner as compared to hourly aggregates and allows users to recognize trends like spikes in request/second. With the introduction of minute level metrics, we now have the following tables in your storage account where Hour and Minute Metrics are stored:

  • $MetricsHourPrimaryTransactionsBlob
  • $MetricsHourPrimaryTransactionsTable
  • $MetricsHourPrimaryTransactionsQueue
  • $MetricsMinutePrimaryTransactionsBlob
  • $MetricsMinutePrimaryTransactionsTable
  • $MetricsMinutePrimaryTransactionsQueue

Please note the change in table names for hourly aggregated metrics. Though the names have changed, your old data will still be available via the new table name too.

To configure minute metrics, please use Set Service Properties REST API for Windows Azure Blob, Table and Queue with 2013-08-15 version. The Windows Azure Portal at this time does not allow configuring minute metrics but it will be available in future.

In addition to the major features listed above, we have the following below additions to our service with this release. More detailed list of changes in 2013-08-15 version can be found at https://msdn.microsoft.com/en-us/library/windowsazure/dd894041.aspx:

  • Copy blob now allows Shared Access Signature (SAS) to be used for the destination blob if the copy is within the same storage account.
  • Windows Azure Blob service now supports Content-Disposition and ability to control response headers like cache-control, content-disposition etc. via query parameters included via SAS. Content-Disposition can also be set statically through Set Blob Properties.
  • Windows Azure Blob service now supports multiple HTTP conditional headers for Get Blob and Get Blob Properties; this feature is particularly useful for access from web-browsers which are going through proxies or CDN servers which may add additional headers.
  • Windows Azure Blob Service now allows Delete Blob operation on uncommitted blob (a blob that is created using Put Block operation but not committed yet using Put Block List API). Previously, the blob needed to be committed before deleting it.
  • List Containers, List Blobs and List Queues starting with 2013-08-15 version will no longer return the URL address field for the resource. This was done to reduce fields that can be reconstructed on client side.
  • Lease Blob and Lease Container starting with 2013-08-15 version will return ETag and Last Modified Time response headers which can be used by the lease holder to easily check if the resource has changed since it was last tracked (e.g., if the blob or its metadata was updated). The ETag value does not change for blob lease operations. Starting with 2013-08-15 version, the container lease operation will not change the ETag too.

We are also releasing an updated Windows Azure Storage Client Library here that supports the features listed above and can be used to exercise the new features. In the next couple of months, we will also release an update to the Windows Azure Storage Emulator for Windows Azure SDK 2.2. This update will support “2013-08-15” version and the new features.

In addition to the above changes, please also read the following two blog posts that discuss known issues and breaking changes for this release:

Storage Emulator Guidance

As mentioned above an updated Windows Azure Storage Emulator is expected to ship with full support of these new features in the next couple of months. Users attempting to develop against the current version of the Storage emulator will receive Bad Request errors as the protocol version (2013-08-15) is unsupported.  Until then, users wanting to use the new features would need to develop and test against a Windows Azure Storage Account to leverage the 2013-08-15 REST version.

Please let us know if you have any further questions either via forum or comments on this post.

Jai Haridas and Brad Calder