CloudQueue.BeginCreateIfNotExist Method
From Storage Client Library NET API
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 |
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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.IAsyncResult
An 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
}
}
}
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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.