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Get Messages

Updated: November 26, 2013

The Get Messages operation retrieves one or more messages from the front of the queue.

The Get Messages request may be constructed as follows. HTTPS is recommended. Replace myaccount with the name of your storage account, and myqueue with the name of your queue:

 

Method Request URI HTTP Version

GET

https://myaccount.queue.core.windows.net/myqueue/messages

HTTP/1.1

When making a request against the emulated storage service, specify the emulator hostname and Queue service port as 127.0.0.1:10001, followed by the emulated storage account name:

 

Method Request URI HTTP Version

GET

http://127.0.0.1:10001/devstoreaccount1/myqueue/messages

HTTP/1.1

For more information, see About Development Storage.

The following additional parameters may be specified on the request URI.

 

Parameter Description

numofmessages

Optional. A nonzero integer value that specifies the number of messages to retrieve from the queue, up to a maximum of 32. If fewer are visible, the visible messages are returned. By default, a single message is retrieved from the queue with this operation.

visibilitytimeout

Required. Specifies the new visibility timeout value, in seconds, relative to server time. The new value must be larger than or equal to 1 second, and cannot be larger than 7 days, or larger than 2 hours on REST protocol versions prior to version 2011-08-18. The visibility timeout of a message can be set to a value later than the expiry time.

timeout

Optional. The timeout parameter is expressed in seconds. For more information, see Setting Timeouts for Queue Service Operations.

The following table describes required and optional request headers.

 

Request Header Description

Authorization

Required. Specifies the authentication scheme, account name, and signature. For more information, see Authentication for the Azure Storage Services.

Date or x-ms-date

Required. Specifies the Coordinated Universal Time (UTC) for the request. For more information, see Authentication for the Azure Storage Services.

x-ms-version

Optional. Specifies the version of the operation to use for this request. For more information, see Versioning for the Azure Storage Services.

x-ms-client-request-id

Optional. Provides a client-generated, opaque value with a 1 KB character limit that is recorded in the analytics logs when storage analytics logging is enabled. Using this header is highly recommended for correlating client-side activities with requests received by the server. For more information, see About Storage Analytics Logging and Windows Azure Logging: Using Logs to Track Storage Requests.

The response includes an HTTP status code and a set of response headers.

A successful operation returns status code 200 (OK).

For information about status codes, see Status and Error Codes.

The response for this operation includes the following headers. The response may also include additional standard HTTP headers. All standard headers conform to the HTTP/1.1 protocol specification.

 

Response header Description

x-ms-request-id

This header uniquely identifies the request that was made and can be used for troubleshooting the request. For more information, see Troubleshooting API Operations.

x-ms-version

Indicates the version of the Queue service used to execute the request. This header is returned for requests made against version 2009-09-19 and later.

Date

A UTC date/time value generated by the service that indicates the time at which the response was initiated.

The response XML for the Get Messages operation is returned in the following format.

The MessageID element is a GUID value that identifies the message in the queue. This value is assigned to the message by the Queue service and is opaque to the client. This value may be used together with the value of the PopReceipt element to delete a message from the queue after it has been retrieved with the Get Messages operation. The value of PopReceipt is also opaque to the client; its only purpose is to ensure that a message may be deleted with the Delete Message operation.

The InsertionTime, ExpirationTime, and TimeNextVisible elements are represented as UTC values and formatted as described in RFC 1123.

The DequeueCount element has a value of 1 the first time the message is dequeued. This value is incremented each time the message is subsequently dequeued.

noteNote
The DequeueCount element is returned in the response body only if the queue was created with version 2009-09-19 of the Queue service.

<QueueMessagesList>
    <QueueMessage>
      <MessageId>string-message-id</MessageId>
      <InsertionTime>insertion-time</InsertionTime>
      <ExpirationTime>expiration-time</ExpirationTime>
      <PopReceipt>opaque-string-receipt-data</PopReceipt>
      <TimeNextVisible>time-next-visible</TimeNextVisible>
      <DequeueCount>integer</DequeueCount>
      <MessageText>message-body</MessageText>
    </QueueMessage>
</QueueMessagesList>

Response Status:
HTTP/1.1 200 OK
Response Headers:
Transfer-Encoding: chunked
Content-Type: application/xml
Date: Fri, 16 Sep 2011 21:04:30 GMT
Server: Windows-Azure-Queue/1.0 Microsoft-HTTPAPI/2.0

Response Body:
<?xml version="1.0" encoding="utf-8"?>
<QueueMessagesList>
  <QueueMessage>
    <MessageId>5974b586-0df3-4e2d-ad0c-18e3892bfca2</MessageId>
    <InsertionTime>Fri, 09 Oct 2009 21:04:30 GMT</InsertionTime>
    <ExpirationTime>Fri, 16 Oct 2009 21:04:30 GMT</ExpirationTime>
    <PopReceipt>YzQ4Yzg1MDItYTc0Ny00OWNjLTkxYTUtZGM0MDFiZDAwYzEw</PopReceipt>
    <TimeNextVisible>Fri, 09 Oct 2009 23:29:20 GMT</TimeNextVisible>
    <DequeueCount>1</DequeueCount>
    <MessageText>PHRlc3Q+dGhpcyBpcyBhIHRlc3QgbWVzc2FnZTwvdGVzdD4=</MessageText>
  </QueueMessage>
</QueueMessagesList>

This operation can be performed by the account owner and by anyone with a shared access signature that has permission to perform this operation.

The message content is retrieved in whatever format was used for the Put Message operation.

When a message is retrieved from the queue, the response includes the message and a pop receipt value, which is required to delete the message. The message is not automatically deleted from the queue, but after it has been retrieved, it is not visible to other clients for the time interval specified by the visibilitytimeout parameter.

If multiple messages are retrieved, each message has an associated pop receipt. The maximum number of messages that may be retrieved at a time is 32.

The client that retrieves the message is expected to delete the message after it has been processed, and before the time specified by the TimeNextVisible element of the response, which is calculated based on the value of the visibilitytimeout parameter. The value of visibilitytimeout is added to the time at which the message is retrieved to determine the value of TimeNextVisible.

A message that is retrieved with a certain visibilitytimeout can reappear again before that specified timeout has elapsed, due to clock skew. Note that a client could infer that a message has already been dequeued by a different client based on the pop receipt, which is unique for each dequeueing of a message. If a client’s pop receipt no longer works to delete or update a message, and the client receives a 404 (Not Found) error, then the message has been dequeued by another client.

Typically, when a consumer retrieves a message via Get Messages, that message is usually reserved for deletion until the visibilitytimeout interval expires, but this behavior is not guaranteed. After the visibilitytimeout interval expires, the message again becomes visible to other consumers. If the message is not subsequently retrieved and deleted by another consumer, the original consumer can delete the message using the original pop receipt.

When a message is retrieved for the first time, its DequeueCount property is set to 1. If it is not deleted and is subsequently retrieved again, the DequeueCount property is incremented. The client may use this value to determine how many times a message has been retrieved.

If the visiblitytimeout or numofmessages parameter is out of range, the service returns status code 400 (Bad Request), along with additional error information, as shown in the following example.


HTTP/1.1 400 One of the query parameters specified in the request URI is outside the permissible range.
Connection: Keep-Alive
Content-Length: 455
Via: 1.1 TK5-PRXY-22
Date: Wed, 02 May 2012 19:37:23 GMT
Content-Type: application/xml
Server: Windows-Azure-Queue/1.0 Microsoft-HTTPAPI/2.0
x-ms-request-id: 6a03526c-ca2c-4358-a63a-b5d096988533
x-ms-version: 2011-08-18

<?xml version="1.0" encoding="utf-8"?>
   <Error>
      <Code>OutOfRangeQueryParameterValue</Code>
      <Message>One of the query parameters specified in the request URI is outside the permissible range.
               RequestId:6a03526c-ca2c-4358-a63a-b5d096988533
               Time:2012-05-02T19:37:24.2438463Z
      </Message>
     <QueryParameterName>numofmessages</QueryParameterName>
     <QueryParameterValue>0</QueryParameterValue>
     <MinimumAllowed>1</MinimumAllowed>
     <MaximumAllowed>32</MaximumAllowed>
   </Error>

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