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Where a lease exists the storage service enforces exclusive writes (put, set and delete operations) however ensuring exclusivity for read operations requires the developer to ensure that all client applications use a lease ID and that only one client at a time has a valid lease ID.Read operations that do not include a lease ID result in shared reads. This operation will succeed const string hello Text = "Blob updated"; var access Condition = Access Condition. Upload Text(hello Text, access Condition: access Condition); Console.If exclusivity of update (put or set) or read operations is required then developers should ensure all clients use a lease ID and that only one client at a time has a valid lease ID.The following container operations can use leases to manage pessimistic concurrency: · Delete Container · Get Container Properties · Get Container Metadata · Set Container Metadata · Get Container ACL · Set Container ACL · Lease Container For more information see: - Specifying Conditional Headers for Blob Service Operations - Lease Container - Lease Blob The table service uses optimistic concurrency checks as the default behavior when you are working with entities, unlike the blob service where you must explicitly choose to perform optimistic concurrency checks.There are three main data concurrency strategies developers will typically consider: 1.Optimistic concurrency – An application performing an update will as part of its update verify if the data has changed since the application last read that data.If you do not explicitly specify a strategy last writes wins is the default.
This indicates to the client that another process has updated the blob since the client retrieved it. If the current ETag value of the blob is the same version as the ETag in the If-Match conditional header in the request, the service performs the requested operation and updates the current ETag value of the blob to show that it has created a new version. ETag); // Now try to update the blob using the orignal ETag provided when the blob was created try catch (Storage Exception ex) The Storage Service also includes support for additional conditional headers such as If-Modified-Since, If-Unmodified-Since and If-None-Match as well as combinations thereof.The snippet below uses an Access Condition object to encapsulate the lease information when it makes a request to update the blob in the storage service. // Acquire lease for 15 seconds string lease = block Blob. For more information about managing lease expiry times and lease ids, see the Lease Blob REST documentation.The following blob operations can use leases to manage pessimistic concurrency: · Put Blob · Get Blob · Get Blob Properties · Set Blob Properties · Get Blob Metadata · Set Blob Metadata · Delete Blob · Put Block · Put Block List · Get Block List · Put Page · Get Page Ranges · Snapshot Blob - lease id optional if a lease exists · Copy Blob - lease id required if a lease exists on the destination blob · Abort Copy Blob - lease id required if an infinite lease exists on the destination blob · Lease Blob Leases on containers enable the same synchronization strategies to be supported as on blobs (exclusive write / shared read, exclusive write / exclusive read and shared write / exclusive read) however unlike blobs the storage service only enforces exclusivity on delete operations.This identifier is updated every time an update operation is performed on an object.The identifier is returned to the client as part of an HTTP GET response using the ETag (entity tag) header that is defined within the HTTP protocol.
It can also be useful where short-lived data streams are being processed.