Mastering IoT and API Integration with AWS: The Wildcard Advantage

In the dynamic world of IoT, agility and security are paramount. Building on my previous articles about Smart IoT Solutions, AWS Serverless APIs, and High Availability, I engineered a solution that is robust, scalable, and secure. In this post, I walk you through how wildcards in MQTT topics simplify device management while ensuring a seamless data flow—from AWS IoT Core, through Lambda and DynamoDB, to a public API endpoint.

The Wildcard Advantage in AWS IoT

Using a wildcard in a topic like bestsense/poc/*/lab allows you to group devices effortlessly. The asterisk substitutes for any single-level value, enabling dynamic device identification and data aggregation without hardcoding individual IDs. This approach simplifies management, enhances scalability, and reduces configuration overhead.

End-to-End Architecture with AWS Services

Critical CLI Steps You Shouldn't Miss

The IoT policy ensures devices can connect, publish, subscribe, and receive on the necessary topics. For example:

bash

cat << 'EOF' > iot-policy.json
{
    "Version": "2012-10-17",
    "Statement": [{
        "Effect": "Allow",
        "Action": ["iot:Connect", "iot:Publish", "iot:Subscribe", "iot:Receive"],
        "Resource": [
            "arn:aws:iot:ap-southeast-2:XXXXXXXXXXXX:client/*",
            "arn:aws:iot:ap-southeast-2:XXXXXXXXXXXX:topic/bestsense/poc/*/lab"
        ]
    }]
}
EOF

aws iot create-policy \
    --policy-name "poc_policy" \
    --policy-document file://iot-policy.json

This rule listens to topics like bestsense/poc/+/lab and triggers the Lambda function:

bash

aws iot create-topic-rule \
    --rule-name "poc_rule" \
    --topic-rule-payload '{
        "sql": "SELECT * FROM '\''bestsense/poc/+/lab'\''",
        "description": "Process sensor data",
        "ruleDisabled": false,
        "awsIotSqlVersion": "2016-03-23",
        "actions": [{
            "lambda": {
                "functionArn": "arn:aws:lambda:ap-southeast-2:XXXXXXXXXXXX:function:Air-net-PoC"
            }
        }]
    }'

Before creating the DynamoDB table, set up a Lambda function that processes IoT data and writes it to the table:

bash

cat << 'EOF' > Air-net-PoC.py
import json
import boto3
from datetime import datetime

dynamodb = boto3.resource('dynamodb')
table = dynamodb.Table('poc_data')

def lambda_handler(event, context):
    try:
        timestamp = str(datetime.utcnow().isoformat())
        response = table.put_item(
            Item={
                'id': timestamp,
                'raw_data': event
            }
        )
        return {'statusCode': 200, 'body': json.dumps('Data stored successfully')}
    except Exception as e:
        return {'statusCode': 500, 'body': json.dumps(str(e))}
EOF

zip Air-net-PoC.zip Air-net-PoC.py

aws lambda create-function \
    --function-name "Air-net-PoC" \
    --runtime python3.9 \
    --handler Air-net-PoC.lambda_handler \
    --role arn:aws:iam::XXXXXXXXXXXX:role/poc_lambda_role \
    --zip-file fileb://Air-net-PoC.zip

Finally, create a Lambda function to expose the data via API Gateway. Sensitive details have been masked:

bash

cat << 'EOF' > mobile--poc.py
import json
import boto3
from decimal import Decimal

dynamodb = boto3.resource('dynamodb')
table = dynamodb.Table('poc_data')

def lambda_handler(event, context):
    try:
        response = table.scan(Limit=10)
        return {
            'statusCode': 200,
            'headers': {
                'Access-Control-Allow-Origin': '*',
                'Content-Type': 'application/json'
            },
            'body': json.dumps(response['Items'], default=str)
        }
    except Exception as e:
        return {
            'statusCode': 500,
            'body': json.dumps(str(e))
        }
EOF

zip mobile--poc.zip mobile--poc.py

aws lambda create-function \
    --function-name "mobile--poc" \
    --runtime python3.9 \
    --handler mobile--poc.lambda_handler \
    --role arn:aws:iam::XXXXXXXXXXXX:role/poc_lambda_role \
    --zip-file fileb://mobile--poc.zip

Securing Public API Access with Reverse Proxy (Note)

In my simulation, data is generated via a Python script, so I did not implement a reverse proxy. However, in a production environment where real data is exposed publicly, setting up a reverse proxy using Nginx or Apache—with SSL/TLS, a Web Application Firewall (WAF), rate limiting, and IP whitelisting—is highly recommended to safeguard your API.

PM1

Very fine particles

PM2.5

Fine particles, like bacteria and smoke

PM4.25

Slightly larger particles

PM10

Larger particles, like dust and pollen

Bringing It All Together

This solution demonstrates how AWS services can be orchestrated to build an efficient, secure IoT-to-API pipeline. The wildcard mechanism simplifies handling diverse device data, while the comprehensive setup—including IoT policies, rules, Lambda functions, and DynamoDB—ensures your data is processed and stored seamlessly. Although my simulation does not include a reverse proxy, I strongly recommend one for any production environment to secure your public endpoints.

Embrace the power of wildcards. Embrace the future. With this approach, your IoT journey becomes both streamlined and secure.

Leonard S Palad

Author: AWS IoT | Cloud Solutions | AI & Automation

Blog | LinkedIn | GitHub | Disclaimer

Created: February 2025

🚀 From Legacy Systems to AI-Powered Innovation: A 20-Year Journey in IT Mastery 🚀

With over 20 years of hands-on IT expertise, he has lived through every major transformation in technology—from on-premise servers to virtualization, cloud computing, and now AI-driven automation. He doesn't just adapt to change—he anticipates it, engineers it, and drives it forward.

An AWS, IoT, and AI enthusiast, he has built solutions that optimize performance, cut costs, and future-proof businesses. Armed with Microsoft, CCNA, VMware, and Citrix certifications, his knowledge spans the entire IT spectrum, allowing him to bridge the gap between legacy infrastructure and modern cloud architectures.

His mission? To empower businesses with high-impact, scalable cloud solutions that don't just keep up—they dominate.

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Securing Public API Access with Reverse Proxy (Note)

PM1

PM2.5

PM4.25

PM10

Bringing It All Together

Leonard S Palad

Author: AWS IoT | Cloud Solutions | AI & Automation