Get Messages operation retrieves one or more messages from the front of the queue.
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|
Emulated Storage Service URI
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|
The following additional parameters may be specified on the request URI.
||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.|
||Optional. Specifies the new visibility timeout value, in seconds, relative to server time. The default value is 30 seconds.
A specified 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.
The following table describes required and optional request headers.
||Required. Specifies the authentication scheme, account name, and signature. For more information, see Authentication for the Azure Storage Services.|
||Required. Specifies the Coordinated Universal Time (UTC) for the request. For more information, see Authentication for the Azure Storage Services.|
||Optional. Specifies the version of the operation to use for this request. For more information, see Versioning for the Azure Storage Services.|
||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 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.
||This header uniquely identifies the request that was made and can be used for troubleshooting the request. For more information, see Troubleshooting API Operations.|
||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.|
||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.
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.
TimeNextVisible elements are represented as UTC values and formatted as described in RFC 1123.
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.
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
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
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>