Evefan is architected to scale horizontally on Cloudflare Workers. It has been tested at 300 events per second over a sustained period of time achieving 99.999% delivery rate.
Evefan consists of several key components:
- Worker Router
- Durable Objects for Batching and Error Tracking
- Queues for Failure Handling
The worker router is the entry point for all incoming requests. It's responsible for:
- Parsing incoming requests
- Routing requests to the appropriate handlers
- Initializing and coordinating with other components
The router is implemented in the app.fetch function, which is exported as the main fetch handler in src/index.ts.
The Batcher Durable Object is used to aggregate events before sending them to destinations. This helps in:
- Reducing the number of API calls to destinations
- Improving overall throughput
- Minimizing the risk of rate limiting
The Batcher is implemented in src/batcher.ts.
The HealthChecker Durable Object is responsible for:
- Tracking errors in processing events for destinations
- Providing insights into the error rates for each destination
The HealthChecker is implemented in src/health.ts.
Queues are used to handle failures when sending events to destinations. The queue system:
- Stores failed events for retry
- Implements a backoff strategy for retries
- Ensures eventual delivery of events
The queue handler is implemented in the handleQueueEventConsumer function in src/queue.ts.