[This topic is part of the Microsoft Azure Storage Client Library 1.7, which has been deprecated. See Storage Client Library for the latest version.]
Begins an asynchronous operation to create the queue if it does not exist. Namespace: Microsoft.WindowsAzure.StorageClient
Assembly: Microsoft.WindowsAzure.StorageClient (in Microsoft.WindowsAzure.StorageClient.dll)
Begins an asynchronous operation to create the queue if it does not exist. Namespace: Microsoft.WindowsAzure.StorageClient
Assembly: Microsoft.WindowsAzure.StorageClient (in Microsoft.WindowsAzure.StorageClient.dll)
Usage
| Visual Basic |
|---|
Dim instance As CloudQueue Dim callback As AsyncCallback Dim state As Object Dim returnValue As IAsyncResult returnValue = instance.BeginCreateIfNotExist(callback, state) |
Syntax
| Visual Basic |
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Public Function BeginCreateIfNotExist ( _ callback As AsyncCallback, _ state As Object _ ) As IAsyncResult |
| C# |
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public IAsyncResult BeginCreateIfNotExist ( AsyncCallback callback, Object state ) |
| C++ |
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public: IAsyncResult^ BeginCreateIfNotExist ( AsyncCallback^ callback, Object^ state ) |
| J# |
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| JScript |
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Parameters
- 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.Example
The following code example illustrates using state when calling BeginCreateIfNotExist.
| C# | Copy Code |
|---|---|
using System;
using System.Diagnostics;
using Microsoft.WindowsAzure;
using Microsoft.WindowsAzure.StorageClient;
namespace QueueAsyncExample
{
public class QueueAsyncStateExample
{
public CloudQueue queueObject;
public object customStateInformation;
// Constructor for the example state class
public QueueAsyncStateExample( CloudQueue queue, object yourAdditionalStateObject )
{
this.queueObject = queue;
this.customStateInformation = yourAdditionalStateObject;
}
// Static call that starts creating a queue if it does not already exist
// (the 'queue' parameter is a CloudQueue reference obtained from CloudQueueClient)
static void CreateQueueIfNotExistAsync( CloudQueue queue, object stateObject )
{
queue.BeginCreateIfNotExist( QueueCreateIfNotExistCallback,
new QueueAsyncStateExample( queue, stateObject ) );
}
// The callback method that is called once the create-if-not-exist operation is complete
static void QueueCreateIfNotExistCallback( IAsyncResult opResult )
{
QueueAsyncStateExample state = (QueueAsyncStateExample) opResult.AsyncState;
CloudQueue queue = state.queueObject;
// End the BeginCreateIfNotExist operation
string yesNo = ( queue.EndCreateIfNotExist( opResult ) ) ? "actually" : "not";
Trace.WriteLine( string.Format( "The '{0}' queue was {1} created...",
queue.Name, yesNo ) );
// ...other asynchronous operations could be started here if appropriate
}
}
}
| |
Remarks
You can specify user-defined metadata on the queue at the time that it is created. To specify metadata for the queue, add name-value pairs to the queue's Metadata.
For guidance about valid names for queues and metadata, see Naming Queues and Metadata.
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.