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  DynamoDB Streams are one of the most powerful—but often under‑explained—features in DynamoDB. A DynamoDB Stream captures every change to items in a table: INSERT MODIFY REMOVE You can then process these changes using: AWS Lambda Kinesis Custom consumers This is how you build event‑driven architectures with DynamoDB. Enable Streams on the Table: You choose a stream view type, e.g.: NEW_IMAGE → only the new item OLD_IMAGE → only the old item NEW_AND_OLD_IMAGES → both KEYS_ONLY → only keys I have table created by the name called " order ". I have enabled "Streams" to capture the changes to the table. And I have added the lambda function to process the streams. Lambda gets triggered , whenever there is a change in the DB items. Below is the lambda snippet: import json def lambda_handler(event, context):     for record in event[ "Records" ]:         event_name = record[ "eventName" ]         keys = record[ "dynamo...

  In this post, let see a demo application which is accessible by the users via API GW and the back end logic for the application is served by AWS lambda function. For persistent storage, we are using DynamoDB table. Lets start with DynamoDB table: I created a DynamoDB table by the name " employee_table ". Table has a primary key " employee_id " of datatype Number. So, any query to the table must be made through the key " employee_id ", else we need to scan the entire table. Let's add an item to the table from console. Now, we added an item to the table. Let's do the same and other action via API GW and Lambda Functions. Let's create a lambda function. One lambda function, based on the query parameter it invokes the function within the lambda. import json import boto 3 from botocore.exceptions import ClientError from decimal import Decimal from boto 3 .dynamodb.conditions import Key # Initialize the DynamoDB client dynamodb = boto 3 .resource(...

  In this post, we will see how to read objects from S3 using AWS API GW. I already have a bucket with a JSON file. Here is the lambda function for reading the object from the bucket. In the below code, I have hardcoded the bucket name and the object name. import json import boto3 client = boto3.client( 's3' ) def lambda_handler ( event , context ):     response = client.get_object(     Bucket = 'demo-001-first' ,-------------> Bucket Name     Key = 'bucket1.json' ,------------------> Object Name )     # convert from streaming to bytes     data_bytes = response[ 'Body' ].read()     #bytes to string     data_strings = data_bytes.decode( "UTF-8" ) # convert from strings to dict     data_dict = json.loads(data_strings)     return {         'statusCode' : 200 ,         'body' : data_dict     } Finally, I have my API GW (REST) as belo...