Architecture

This project implements the CAMARA Energy Footprint Notification (EFN) API using an event-driven microservices architecture.

Overview

The system is composed of several decoupled services that communicate primarily through CloudEvents and a shared MongoDB database. The EFN API enables API consumers to retrieve energy consumption and carbon footprint information for services deployed on the operator's infrastructure.

Components

1. API Service (cmd/api)

   • Role: Entry point for API consumers.
   • Responsibilities:
     • Validates incoming requests against the OpenAPI specification.
     • Authorizes access to requested application instances via Policy Decision Point (PDP).
     • Creates job records in MongoDB.
     • Publishes gatherinfo.requested events to the event broker.
   • Endpoints:
     • POST /calculate-energy-consumption - Calculate energy consumption for specified applications.
     • POST /calculate-carbon-footprint - Calculate carbon footprint for specified applications.

2. Worker Service (cmd/worker)

   • Role: Performs the actual energy/carbon calculations.
   • Responsibilities:
     • Listens for multiple event types (gatherinfo.requested, app.consumption.requested, networkelement.energy.requested, networkelement.traffic.requested, calculation.requested).
     • For each application instance:
       • Retrieves energy consumption from the Cloud Observability interface.
       • Retrieves traffic volumes from the Traffic Volume interface.
       • Calculates network elements energy consumption proportionally.
     • Aggregates results and calculates total energy consumption or carbon footprint.
     • Stores calculation results to MongoDB.
     • Publishes notification.requested or notification.error.requested events.

3. Notification Service (cmd/notification)

   • Role: Handles callbacks to the API consumer.
   • Responsibilities:
     • Listens for notification.requested and notification.error.requested events.
     • Retrieves the full job result from MongoDB.
     • Sends a webhook notification to the sink URL provided in the initial subscription request.
     • Publishes notification.sent event after successful delivery.

4. Sink Receiver (cmd/sinkreceiver)

   • Role: Testing utility.
   • Responsibilities:
     • Acts as a mock endpoint for receiving webhook notifications during local development.
     • Logs all incoming requests for debugging purposes.

Knative Eventing

The system relies on Knative Eventing for asynchronous communication. The following table describes the events and their flow through the system.

Event Type	Source	Producer	Consumer(s)	Description
it.tim.efn.gatherinfo.requested	urn:tim:efn-api	API	Worker	Sent when a user requests energy consumption or carbon footprint calculation. Contains the job ID and request details.
it.tim.efn.app.consumption.requested	urn:tim:efn-worker	Worker	Worker	Sent to get energy consumption for an application instance.
it.tim.efn.networkelement.energy.requested	urn:tim:efn-worker	Worker	Worker	Sent to get energy consumption for a single network element.
it.tim.efn.networkelement.traffic.requested	urn:tim:efn-worker	Worker	Worker	Sent to get traffic volume info for network elements.
it.tim.efn.calculation.requested	urn:tim:efn-worker	Worker	Worker	Sent to trigger final calculation after all values are gathered.
it.tim.efn.notification.requested	urn:tim:efn-worker	Worker	Notification	Sent when the calculation has completed successfully.
it.tim.efn.notification.error.requested	urn:tim:efn-worker	Worker	Notification	Sent when an error occurs during processing.
it.tim.efn.notification.sent	urn:tim:efn-notification	Notification	N/A	Sent when a notification has been delivered.

Triggers

The following Knative Triggers are defined to route events from the Broker to the services:

• gatherinfo-requested-trigger: Routes gatherinfo.requested -> efn-worker.
• app-consumption-requested-trigger: Routes app.consumption.requested -> efn-worker.
• networkelement-energy-requested-trigger: Routes networkelement.energy.requested -> efn-worker.
• networkelement-traffic-requested-trigger: Routes networkelement.traffic.requested -> efn-worker.
• calculation-requested-trigger: Routes calculation.requested -> efn-worker.
• notification-requested-trigger: Routes notification.requested -> efn-notification.
• notification-error-requested-trigger: Routes notification.error.requested -> efn-notification.

Data Flow

1. Request: User sends POST /calculate-energy-consumption or POST /calculate-carbon-footprint.
2. Validation: API validates request against OpenAPI spec and time period constraints.
3. Authorization: API checks if user is authorized to access the requested application instances.
4. Persistence: API creates a Job with the request information in MongoDB.
5. Event: API sends gatherinfo.requested to Broker.
6. Processing: Worker receives event and for each application:
   • Retrieves application energy consumption from Cloud Observability.
   • Retrieves traffic volumes for network elements.
   • Calculates proportional network energy consumption.
7. Calculation: Worker aggregates all results and calculates final energy/carbon value.
8. Completion: Worker updates job status to completed and sends notification.requested.
9. Notification: Notification service receives completion event and sends webhook to user's sink URL, then emits notification.sent.