Renova Cloud reviewed the customer’s requirements and identified the following:

• The integration should be implemented in code on a platform where it can be easily modified to accommodate future needs
• The platform and services used must have high availability and reliability; downtime should be avoided and the status of the services easy to monitor
• Scalability and elasticity; in the beginning the number of IoT-enabled devices is small, but it’s expected to grow with a pace that is hard to predict
• Cost-effectiveness: since the goal of the project is to build a custom integration between existing platforms, the integration itself should not be a major cost factor

All the requirements suggested that a highly reliable hosting platform with managed services was needed. Selecting AWS to host the services was agreed between Renova Cloud and customer, who saw the advantages of being able to extend the solution in the future.

Renova Cloud identified the following major tasks for the solution:

1. Listen to TUYA IoT Publisher (Pulsar) for device events of interest
2. Call TUYA API to retrieve more details of devices, customers and customer contacts
3. Call SAP C4C API to add or update devices, customers and service requests
4. Store all events and logs for potential auditing, troubleshooting and review purposes
5. Package data by device so that system admin retrieve monitoring reports of devices

The tasks 1-3 have unpredictable volume which depends mainly on the amount of events of interest, such as new user registrations, new device installations and any faults occurring. The task 4 involves storing the data for events of interest, so the volume is related to the cumulative amount of such events in the past. The task 5 involves user such as system administrator accessing the monitoring on-demand, the volume is expected to be correlated with the number of device faults and service requests happening in the recent time period.

The requirements lend themselves well to serverless architecture, with the tasks divided into small functions run whenever needed and can scale massively due to the parallel execution. Renova Cloud drafted an AWS architecture using Lambda functions written in Python and orchestrated with Step Functions, with API Gateway in front and communicating utilizing SQS queues. As storage solution, DynamoDB is used for short term and serving monitoring data for status dashboards, while S3 is used for archival. The calls to external APIs of TUYA and SAP C4C are managed with Lambda functions, with requests and responses logged in CloudWatch. EventBridge sets the schedule of device status monitoring.

TUYA message queue uses Apache Pulsar so an implementation of a subscriber was required. Renova Cloud wrote the Pulsar subscriber application in Java code running in ECS as Docker container with image versions stored in ECR. To achieve the best scalability and elasticity, ECS Fargate launch type is used and therefore the solution is fully serverless.

To ensure security of the solution, all the credentials are stored in Secrets Manager and retrieved securely by the applications. S3 buckets are encrypted using keys from KMS. If any errors are encountered during the workflows, these are logged and SNS notifications are sent to admins.

The overall architecture integrates many AWS serverless services as a complete solution.