CloudPageBlob.BeginOpenRead Method (AccessCondition, BlobRequestOptions, OperationContext, AsyncCallback, Object)

Article
05/14/2014

Begins an asynchronous operation to open a stream for reading from the blob.

Namespace: Microsoft.WindowsAzure.Storage.Blob
Assembly: Microsoft.WindowsAzure.Storage (in Microsoft.WindowsAzure.Storage.dll)

Syntax

'Declaration
<DoesServiceRequestAttribute> _
Public Function BeginOpenRead ( _
    accessCondition As AccessCondition, _
    options As BlobRequestOptions, _
    operationContext As OperationContext, _
    callback As AsyncCallback, _
    state As Object _
) As ICancellableAsyncResult

[DoesServiceRequestAttribute] 
public ICancellableAsyncResult BeginOpenRead (
    AccessCondition accessCondition,
    BlobRequestOptions options,
    OperationContext operationContext,
    AsyncCallback callback,
    Object state
)

[DoesServiceRequestAttribute] 
public:
virtual ICancellableAsyncResult^ BeginOpenRead (
    AccessCondition^ accessCondition, 
    BlobRequestOptions^ options, 
    OperationContext^ operationContext, 
    AsyncCallback^ callback, 
    Object^ state
) sealed

Parameters

accessCondition
An AccessCondition object that represents the condition that must be met in order for the request to proceed. If null, no condition is used.

options
A BlobRequestOptions object that specifies additional options for the request.

operationContext
An OperationContext object that represents the context for the current operation.

callback
An AsyncCallback delegate that will receive notification when the asynchronous operation completes.

state
A user-defined object that will be passed to the callback delegate.

Return Value

An ICancellableAsyncResult that references the asynchronous operation.

Remarks

On the Stream object returned by the EndOpenRead method, the EndRead method must be called exactly once for every BeginRead call. Failing to end the read process before beginning another read process can cause unexpected behavior.

Note that this method always makes a call to the BeginFetchAttributes(AccessCondition,BlobRequestOptions,OperationContext,AsyncCallback,Object) method under the covers.

Set the StreamMinimumReadSizeInBytes property before calling this method to specify the minimum number of bytes to buffer when reading from the stream. The value must be at least 16 KB.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Platforms

Development Platforms

Windows Vista, Windows 7 and Windows Server 2008