ReceiveMessageRequest Class | AWS SDK for .NET V3

Container for the parameters to the ReceiveMessage operation. Retrieves one or more messages (up to 10), from the specified queue. Using the WaitTimeSeconds parameter enables long-poll support. For more information, see Amazon SQS Long Polling in the Amazon SQS Developer Guide.

Short poll is the default behavior where a weighted random set of machines is sampled on a ReceiveMessage call. Therefore, only the messages on the sampled machines are returned. If the number of messages in the queue is small (fewer than 1,000), you most likely get fewer messages than you requested per ReceiveMessage call. If the number of messages in the queue is extremely small, you might not receive any messages in a particular ReceiveMessage response. If this happens, repeat the request.

For each message returned, the response includes the following:

The message body.
An MD5 digest of the message body. For information about MD5, see RFC1321.
The MessageId you received when you sent the message to the queue.
The receipt handle.
The message attributes.
An MD5 digest of the message attributes.

The receipt handle is the identifier you must provide when deleting the message. For more information, see Queue and Message Identifiers in the Amazon SQS Developer Guide.

You can provide the VisibilityTimeout parameter in your request. The parameter is applied to the messages that Amazon SQS returns in the response. If you don't include the parameter, the overall visibility timeout for the queue is used for the returned messages. The default visibility timeout for a queue is 30 seconds.

In the future, new attributes might be added. If you write code that calls this action, we recommend that you structure your code so that it can handle new attributes gracefully.

Inheritance Hierarchy

System.Object
  Amazon.Runtime.AmazonWebServiceRequest
    Amazon.SQS.AmazonSQSRequest
      Amazon.SQS.Model.ReceiveMessageRequest

Namespace: Amazon.SQS.Model
Assembly: AWSSDK.SQS.dll
Version: 3.x.y.z

Syntax

public class ReceiveMessageRequest : AmazonSQSRequest
         IAmazonWebServiceRequest

The ReceiveMessageRequest type exposes the following members

Constructors

	Name	Description
	ReceiveMessageRequest()	Empty constructor used to set properties independently even when a simple constructor is available
	ReceiveMessageRequest(string)	Instantiates ReceiveMessageRequest with the parameterized properties

Properties

Name	Type	Description
AttributeNames	System.Collections.Generic.List<System.String>	Gets and sets the property AttributeNames. This parameter has been discontinued but will be supported for backward compatibility. To provide attribute names, you are encouraged to use `MessageSystemAttributeNames`. A list of attributes that need to be returned along with each message. These attributes include: `All` – Returns all values. `ApproximateFirstReceiveTimestamp` – Returns the time the message was first received from the queue (epoch time in milliseconds). `ApproximateReceiveCount` – Returns the number of times a message has been received across all queues but not deleted. `AWSTraceHeader` – Returns the X-Ray trace header string. `SenderId` For a user, returns the user ID, for example `ABCDEFGHI1JKLMNOPQ23R`. For an IAM role, returns the IAM role ID, for example `ABCDE1F2GH3I4JK5LMNOP:i-a123b456`. `SentTimestamp` – Returns the time the message was sent to the queue (epoch time in milliseconds). `SqsManagedSseEnabled` – Enables server-side queue encryption using SQS owned encryption keys. Only one server-side encryption option is supported per queue (for example, SSE-KMS or SSE-SQS). `MessageDeduplicationId` – Returns the value provided by the producer that calls the `SendMessage` action. `MessageGroupId` – Returns the value provided by the producer that calls the `SendMessage` action. Messages with the same `MessageGroupId` are returned in sequence. `SequenceNumber` – Returns the value provided by Amazon SQS.
MaxNumberOfMessages	System.Int32	Gets and sets the property MaxNumberOfMessages. The maximum number of messages to return. Amazon SQS never returns more messages than this value (however, fewer messages might be returned). Valid values: 1 to 10. Default: 1.
MessageAttributeNames	System.Collections.Generic.List<System.String>	Gets and sets the property MessageAttributeNames. The name of the message attribute, where N is the index. The name can contain alphanumeric characters and the underscore (`_`), hyphen (`-`), and period (`.`). The name is case-sensitive and must be unique among all attribute names for the message. The name must not start with AWS-reserved prefixes such as `AWS.` or `Amazon.` (or any casing variants). The name must not start or end with a period (`.`), and it should not have periods in succession (`..`). The name can be up to 256 characters long. When using `ReceiveMessage`, you can send a list of attribute names to receive, or you can return all of the attributes by specifying `All` or `.` in your request. You can also use all message attributes starting with a prefix, for example `bar.`.
MessageSystemAttributeNames	System.Collections.Generic.List<System.String>	Gets and sets the property MessageSystemAttributeNames. A list of attributes that need to be returned along with each message. These attributes include: `All` – Returns all values. `ApproximateFirstReceiveTimestamp` – Returns the time the message was first received from the queue (epoch time in milliseconds). `ApproximateReceiveCount` – Returns the number of times a message has been received across all queues but not deleted. `AWSTraceHeader` – Returns the X-Ray trace header string. `SenderId` For a user, returns the user ID, for example `ABCDEFGHI1JKLMNOPQ23R`. For an IAM role, returns the IAM role ID, for example `ABCDE1F2GH3I4JK5LMNOP:i-a123b456`. `SentTimestamp` – Returns the time the message was sent to the queue (epoch time in milliseconds). `SqsManagedSseEnabled` – Enables server-side queue encryption using SQS owned encryption keys. Only one server-side encryption option is supported per queue (for example, SSE-KMS or SSE-SQS). `MessageDeduplicationId` – Returns the value provided by the producer that calls the `SendMessage` action. `MessageGroupId` – Returns the value provided by the producer that calls the `SendMessage` action. Messages with the same `MessageGroupId` are returned in sequence. `SequenceNumber` – Returns the value provided by Amazon SQS.
QueueUrl	System.String	Gets and sets the property QueueUrl. The URL of the Amazon SQS queue from which messages are received. Queue URLs and names are case-sensitive.
ReceiveRequestAttemptId	System.String	Gets and sets the property ReceiveRequestAttemptId. This parameter applies only to FIFO (first-in-first-out) queues. The token used for deduplication of `ReceiveMessage` calls. If a networking issue occurs after a `ReceiveMessage` action, and instead of a response you receive a generic error, it is possible to retry the same action with an identical `ReceiveRequestAttemptId` to retrieve the same set of messages, even if their visibility timeout has not yet expired. You can use `ReceiveRequestAttemptId` only for 5 minutes after a `ReceiveMessage` action. When you set `FifoQueue`, a caller of the `ReceiveMessage` action can provide a `ReceiveRequestAttemptId` explicitly. It is possible to retry the `ReceiveMessage` action with the same `ReceiveRequestAttemptId` if none of the messages have been modified (deleted or had their visibility changes). During a visibility timeout, subsequent calls with the same `ReceiveRequestAttemptId` return the same messages and receipt handles. If a retry occurs within the deduplication interval, it resets the visibility timeout. For more information, see Visibility Timeout in the Amazon SQS Developer Guide. If a caller of the `ReceiveMessage` action still processes messages when the visibility timeout expires and messages become visible, another worker consuming from the same queue can receive the same messages and therefore process duplicates. Also, if a consumer whose message processing time is longer than the visibility timeout tries to delete the processed messages, the action fails with an error. To mitigate this effect, ensure that your application observes a safe threshold before the visibility timeout expires and extend the visibility timeout as necessary. While messages with a particular `MessageGroupId` are invisible, no more messages belonging to the same `MessageGroupId` are returned until the visibility timeout expires. You can still receive messages with another `MessageGroupId` as long as it is also visible. If a caller of `ReceiveMessage` can't track the `ReceiveRequestAttemptId`, no retries work until the original visibility timeout expires. As a result, delays might occur but the messages in the queue remain in a strict order. The maximum length of `ReceiveRequestAttemptId` is 128 characters. `ReceiveRequestAttemptId` can contain alphanumeric characters (`a-z`, `A-Z`, `0-9`) and punctuation (!"#$%&'()+,-./:;<=>?@[\]^_`{\|}~). For best practices of using `ReceiveRequestAttemptId`, see Using the ReceiveRequestAttemptId Request Parameter in the Amazon SQS Developer Guide*.
VisibilityTimeout	System.Int32	Gets and sets the property VisibilityTimeout. The duration (in seconds) that the received messages are hidden from subsequent retrieve requests after being retrieved by a `ReceiveMessage` request. If not specified, the default visibility timeout for the queue is used, which is 30 seconds. Understanding `VisibilityTimeout`: When a message is received from a queue, it becomes temporarily invisible to other consumers for the duration of the visibility timeout. This prevents multiple consumers from processing the same message simultaneously. If the message is not deleted or its visibility timeout is not extended before the timeout expires, it becomes visible again and can be retrieved by other consumers. Setting an appropriate visibility timeout is crucial. If it's too short, the message might become visible again before processing is complete, leading to duplicate processing. If it's too long, it delays the reprocessing of messages if the initial processing fails. You can adjust the visibility timeout using the `--visibility-timeout` parameter in the `receive-message` command to match the processing time required by your application. A message that isn't deleted or a message whose visibility isn't extended before the visibility timeout expires counts as a failed receive. Depending on the configuration of the queue, the message might be sent to the dead-letter queue. For more information, see Visibility Timeout in the Amazon SQS Developer Guide.
WaitTimeSeconds	System.Int32	Gets and sets the property WaitTimeSeconds. The duration (in seconds) for which the call waits for a message to arrive in the queue before returning. If a message is available, the call returns sooner than `WaitTimeSeconds`. If no messages are available and the wait time expires, the call does not return a message list. If you are using the Java SDK, it returns a `ReceiveMessageResponse` object, which has a empty list instead of a Null object. To avoid HTTP errors, ensure that the HTTP response timeout for `ReceiveMessage` requests is longer than the `WaitTimeSeconds` parameter. For example, with the Java SDK, you can set HTTP transport settings using the NettyNioAsyncHttpClient for asynchronous clients, or the ApacheHttpClient for synchronous clients.

Examples

This example shows how to receive a message.

Receive message example

var client = new AmazonSQSClient();

var request = new ReceiveMessageRequest
{
  AttributeNames = new List<string>() { "All" },
  MaxNumberOfMessages = 5,
  QueueUrl = "https://sqs.us-east-1.amazonaws.com/80398EXAMPLE/MyTestQueue",
  VisibilityTimeout = (int)TimeSpan.FromMinutes(10).TotalSeconds,
  WaitTimeSeconds = (int)TimeSpan.FromSeconds(5).TotalSeconds
};

var response = client.ReceiveMessage(request);

if (response.Messages.Count > 0)
{
  foreach (var message in response.Messages)
  {
    Console.WriteLine("For message ID '" + message.MessageId + "':");
    Console.WriteLine("  Body: " + message.Body);
    Console.WriteLine("  Receipt handle: " + message.ReceiptHandle);
    Console.WriteLine("  MD5 of body: " + message.MD5OfBody);
    Console.WriteLine("  MD5 of message attributes: " +
      message.MD5OfMessageAttributes);
    Console.WriteLine("  Attributes:");

    foreach (var attr in message.Attributes)
    {
      Console.WriteLine("    " + attr.Key + ": " + attr.Value);
    }
  }
}
else
{
  Console.WriteLine("No messages received.");
}

Version Information

.NET:
Supported in: 8.0 and newer, Core 3.1

.NET Standard:
Supported in: 2.0

.NET Framework:
Supported in: 4.5 and newer, 3.5