Versioning for the Azure Storage Services

The Microsoft Azure storage services support multiple versions. To make a request against the storage services, you must specify the version that you want to use for that operation, unless the request is anonymous.

The current version of the Azure storage services is 2016-05-31, and using that version is recommended where possible. For a list of all other supported versions, and for information about using each version, see Azure Storage Services Versions 2015-12-11 and Earlier.

Version 2016-05-31

Version 2016-05-31 includes these changes:

  • The maximum size of blocks has been increased to 100 MB. This means that the maximum size of a block blob is now 5,000,000 MB, or about 4.75 TB.
  • The public access level of a container is now returned from the List Containers and Get Container Properties APIs. Previously this information could only be obtained by calling Get Container ACL.
  • The Put Message API now returns information about the message that was just added, including the pop receipt. This enables the you to call Update Message and Delete Message on the newly enqueued message.
  • The List Directories and Files API now accepts a new parameter that limits the listing to a specified prefix.
  • Several error messages have been clarified or made more specific.
  • All table APIs now accept and enforce the timeout query parameter.
  • The stored Content-MD5 property is now returned when requesting a range of a blob or file. Previously this was only returned for full blob and file downloads.
  • A new Incremental Copy Blob API is now available. This allows efficient copying and backup of page blob snapshots.
  • Using If-None-Match: * will now fail when reading a blob. Previously this header was ignored for blob reads.
  • During authentication, the canonicalized header list now includes headers with empty values. Previously these were omitted from the list.

Specifying Storage Service Versions in Requests

How you specify the version of the storage services to use for a request relates to how that request is authenticated. The following sections describe authentication options and how the service version is specified for each:

  1. Requests using Shared Key or Shared Key Lite. To authenticate a request with Shared Key/Shared Key Lite, you must pass the x-ms-version header on the request. In the case of the Blob service, you can specify the default version for all requests by calling Set Blob Service Properties.

  2. Requests using a Shared Access Signature (SAS). You can specify two versioning options on a shared access signature. If specified, the optional api-version header indicates which service version to use to execute the API operation. The SignedVersion (sv) parameter specifies the service version to use to authorize and authenticate the request made with the SAS. If the api-version header is not specified, then the value of the SignedVersion (sv) parameter also indicates the version to use to execute the API operation.

  3. Requests using anonymous access. In the case of anonymous access against the Blob service, no version is passed in; the heuristics for which version is used for the request are described below.

Requests Authenticated Using Shared Key/Shared Key Lite

To authenticate a request with Shared Key/Shared Key Lite, specify the x-ms-version header on the request. The x-ms-version request header value must be specified in the format YYYY-MM-DD. For example:

Request Headers:  
x-ms-version: 2015-12-11

The following rules indicates how requests using Shared Key/Shared Key Lite are evaluated to determine the version to use in processing the request.

  • If a request has a valid x-ms-version header, the storage service uses the specified version. All requests to the Table and Queue services that do not use a shared access signature must specify an x-ms-version header. All requests to the Blob service that do not use a shared access signature must specify an x-ms-version header unless the default version has been set, as described below.

  • If a request to the Blob service does not have an x-ms-version header, but the account owner has set a default version using Set Blob Service Properties, then the specified default version is used as the version for the request.

Requests Authenticated With a Shared Access Signature

A shared access signature (SAS) generated using version 2014-02-14 or later supports two versioning options:

  • The api-version query parameter defines the REST protocol version to use for processing a request made using the SAS.

  • The SignedVersion (sv) query parameter defines the SAS version to use for authentication and authorization.

    The SignedVersion query parameter is used for authentication and authorization when a client makes a request using the SAS. Authentication and authorization parameters such as si, sr, sp, sig, st, se, tn, spk, srk, epk, and erk are all interpreted using the specified version.

    REST protocol parameters such as rscc, rscd, rsce, rscl, and rsct are enforced using the version provided in the api-version parameter header. If the api-version header is not specified, then the service version provided for SignedVersion is used.

    Note that the api-version parameter is not part of the string-to-sign in the authentication as described in Constructing a Service SAS.

    The following table explains the versioning scheme used by the service for authentication and authorization and for calling the REST protocol when the SignedVersion parameter is set to version 2014-02-14 or later.

Value of api-version parameter Version used for authentication and authorization Version used for protocol behavior
Not specified Version specified in the sv parameter Version specified in the sv parameter
Any valid storage services version in format XXXX-XX-XX Version specified in the sv parameter Valid storage services version XXXX-XX-XX

Example 1

The following sample request calls List Blobs with sv=2015-04-05, and without the api-version parameter.

https://myaccount.blob.core.windows.net/mycontainer?restype=container&comp=list&sv=2015-04-05&si=readpolicy&sig=a39 %2BYozJhGp6miujGymjRpN8tsrQfLo9Z3i8IRyIpnQ%3d

In this case, the service authenticates and authorizes the request using version 2015-04-05 and also executes the operation using version 2015-04-05.

Example 2

The following sample request calls List Blobs with sv=2015-04-05 and with the api-version parameter.

https://myaccount.blob.core.windows.net/mycontainer?restype=container&comp=list&sv=2015-04-05&si=readpolicy&sig=a39 %2BYozJhGp6miujGymjRpN8tsrQfLo9Z3i8IRyIpnQ%3d&api-version=2012-02-12

Here, the service authenticates and authorizes the request using version 2015-04-05 and executes the operation using version 2012-02-12.

Note

The .NET Storage Client Library will always set the REST protocol version (in the api-version parameter) to the version that it is based on.

Requests Via Anonymous Access

If a request to the Blob service does not specify the x-ms-version header, and the default version for the service has not been set using Set Blob Service Properties, then the earliest version of the Blob service is used to process the request. However, if the container was made public with a Set Container ACL operation performed using version 2009-09-19 or newer, then the request is processed using version 2009-09-19.

See Also

Storage Services REST
Versioning Best Practices
Protocol Version Support for .NET Client Library Versions