| CloudBlockBlob.BeginDownloadBlockList Method (BlockListingFilter, BlobRequestOptions, AsyncCallback, Object) |
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Begins an asynchronous operation to return an enumerable collection of the blob's blocks, using the specified block list filter, using a conditional request based on the BlobRequestOptions specified. Namespace: Microsoft.WindowsAzure.StorageClient
Assembly: Microsoft.WindowsAzure.StorageClient (in Microsoft.WindowsAzure.StorageClient.dll)
Usage
| Visual Basic |
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Dim instance As CloudBlockBlob Dim blockListingFilter As BlockListingFilter Dim options As BlobRequestOptions Dim callback As AsyncCallback Dim state As Object Dim returnValue As IAsyncResult returnValue = instance.BeginDownloadBlockList(blockListingFilter, options, callback, state) |
Syntax
| Visual Basic |
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Public Function BeginDownloadBlockList ( _ blockListingFilter As BlockListingFilter, _ options As BlobRequestOptions, _ callback As AsyncCallback, _ state As Object _ ) As IAsyncResult |
| C# |
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public IAsyncResult BeginDownloadBlockList ( BlockListingFilter blockListingFilter, BlobRequestOptions options, AsyncCallback callback, Object state ) |
| C++ |
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public: IAsyncResult^ BeginDownloadBlockList ( BlockListingFilter blockListingFilter, BlobRequestOptions^ options, AsyncCallback^ callback, Object^ state ) |
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Parameters
- blockListingFilter
Type: Microsoft.WindowsAzure.StorageClient.BlockListingFilter
One of the enumeration values that indicates whether to return committed blocks, uncommitted blocks, or both.
- options
Type: Microsoft.WindowsAzure.StorageClient.BlobRequestOptions
An object that specifies any additional options for the request.
- callback
Type: System.AsyncCallback
The callback delegate that will receive notification when the asynchronous operation completes.
- state
Type: System.Object
A user-defined object that will be passed to the callback delegate.
Return Value
Type: System.IAsyncResultAn IAsyncResult that references the asynchronous operation.Remarks
The BeginDownloadBlockList method begins an operation to download the block list for the blob, using the specified block listing filter. The block listing filter specifies whether to include only committed blobs, only uncommitted blobs, or both.
The committed block list includes the list of blocks that have been successfully committed to a blob. The list of committed blocks is returned in the same order that they were committed to the blob.
You can use the uncommitted block list to determine which blocks are missing from the blob in cases where either writing a block or committing the block list has failed. The list of uncommitted blocks is returned beginning with the most recently uploaded block to the oldest uploaded block. If a block ID has been uploaded more than once, only the most recently uploaded block appears in the list.
When blocks have been uploaded but the blob has not yet been committed with PutBlockList, calling BeginDownloadBlockList with All returns the uncommitted blocks.