# PublishBatchRequestEntry
Contains the details of a single Amazon SNS message along with an `Id` that identifies a message within the batch.
## Contents
** Id **
An identifier for the message in this batch.
The `Ids` of a batch request must be unique within a request.
This identifier can have up to 80 characters. The following characters are accepted: alphanumeric characters, hyphens(-), and underscores (\$1).
Type: String
Required: Yes
** Message **
The body of the message.
Type: String
Required: Yes
** MessageAttributes ** MessageAttributes.entry.N.Name (key) MessageAttributes.entry.N.Value (value)
Each message attribute consists of a `Name`, `Type`, and `Value`. For more information, see [Amazon SNS message attributes](https://docs.aws.amazon.com/sns/latest/dg/sns-message-attributes.html) in the Amazon SNS Developer Guide.
Type: String to [MessageAttributeValue](API_MessageAttributeValue.md) object map
Required: No
** MessageDeduplicationId **
This parameter applies only to FIFO (first-in-first-out) topics.
+ This parameter applies only to FIFO (first-in-first-out) topics. The `MessageDeduplicationId` can contain up to 128 alphanumeric characters `(a-z, A-Z, 0-9)` and punctuation `(!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~)`.
+ Every message must have a unique `MessageDeduplicationId`, which is a token used for deduplication of sent messages within the 5 minute minimum deduplication interval.
+ The scope of deduplication depends on the `FifoThroughputScope` attribute, when set to `Topic` the message deduplication scope is across the entire topic, when set to `MessageGroup` the message deduplication scope is within each individual message group.
+ If a message with a particular `MessageDeduplicationId` is sent successfully, subsequent messages within the deduplication scope and interval, with the same `MessageDeduplicationId`, are accepted successfully but aren't delivered.
+ Every message must have a unique `MessageDeduplicationId`.
+ You may provide a `MessageDeduplicationId` explicitly.
+ If you aren't able to provide a `MessageDeduplicationId` and you enable `ContentBasedDeduplication` for your topic, Amazon SNS uses a SHA-256 hash to generate the `MessageDeduplicationId` using the body of the message (but not the attributes of the message).
+ If you don't provide a `MessageDeduplicationId` and the topic doesn't have `ContentBasedDeduplication` set, the action fails with an error.
+ If the topic has a `ContentBasedDeduplication` set, your `MessageDeduplicationId` overrides the generated one.
+ When `ContentBasedDeduplication` is in effect, messages with identical content sent within the deduplication scope and interval are treated as duplicates and only one copy of the message is delivered.
+ If you send one message with `ContentBasedDeduplication` enabled, and then another message with a `MessageDeduplicationId` that is the same as the one generated for the first `MessageDeduplicationId`, the two messages are treated as duplicates, within the deduplication scope and interval, and only one copy of the message is delivered.
The `MessageDeduplicationId` is available to the consumer of the message (this can be useful for troubleshooting delivery issues).
If a message is sent successfully but the acknowledgement is lost and the message is resent with the same `MessageDeduplicationId` after the deduplication interval, Amazon SNS can't detect duplicate messages.
Amazon SNS continues to keep track of the message deduplication ID even after the message is received and deleted.
Type: String
Required: No
** MessageGroupId **
FIFO topics: The tag that specifies that a message belongs to a specific message group. Messages that belong to the same message group are processed in a FIFO manner (however, messages in different message groups might be processed out of order). To interleave multiple ordered streams within a single topic, use `MessageGroupId` values (for example, session data for multiple users). In this scenario, multiple consumers can process the topic, but the session data of each user is processed in a FIFO fashion. You must associate a non-empty `MessageGroupId` with a message. If you do not provide a `MessageGroupId`, the action fails.
Standard topics: The `MessageGroupId` is optional and is forwarded only to Amazon SQS standard subscriptions to activate [fair queues](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-fair-queues.html). The `MessageGroupId` is not used for, or sent to, any other endpoint types.
The length of `MessageGroupId` is 128 characters.
`MessageGroupId` can contain alphanumeric characters `(a-z, A-Z, 0-9)` and punctuation `(!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~)`.
Type: String
Required: No
** MessageStructure **
Set `MessageStructure` to `json` if you want to send a different message for each protocol. For example, using one publish action, you can send a short message to your SMS subscribers and a longer message to your email subscribers. If you set `MessageStructure` to `json`, the value of the `Message` parameter must:
+ be a syntactically valid JSON object; and
+ contain at least a top-level JSON key of "default" with a value that is a string.
You can define other top-level keys that define the message you want to send to a specific transport protocol (for example, http).
Type: String
Required: No
** Subject **
The subject of the batch message.
Type: String
Required: No
## See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
+ [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/sns-2010-03-31/PublishBatchRequestEntry)
+ [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/sns-2010-03-31/PublishBatchRequestEntry)
+ [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/sns-2010-03-31/PublishBatchRequestEntry)