1  """DynamoDB table for WhatsApp message buffering with stream and TTL.
 2  
 3  Uses from_phone as partition key so messages from the same user land in the
 4  same shard and are processed together by the tumbling window.
 5  
 6  Based on: https://github.com/aws-samples/sample-whatsapp-end-user-messaging-connect-chat
 7  """
 8  
 9  from constructs import Construct
10  from aws_cdk import (
11      RemovalPolicy,
12      aws_dynamodb as ddb,
13  )
14  
15  
16  class MessageDatabase(Construct):
17      """DynamoDB table with stream for tumbling window message aggregation."""
18  
19      def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
20          super().__init__(scope, construct_id, **kwargs)
21  
22          self.table = ddb.Table(
23              self,
24              "MessagesTable",
25              partition_key=ddb.Attribute(name="from_phone", type=ddb.AttributeType.STRING),
26              sort_key=ddb.Attribute(name="id", type=ddb.AttributeType.STRING),
27              billing_mode=ddb.BillingMode.PAY_PER_REQUEST,
28              removal_policy=RemovalPolicy.DESTROY,
29              stream=ddb.StreamViewType.NEW_IMAGE,
30              time_to_live_attribute="ttl",
31          )