Ants are remarkable creatures. Each one acts autonomously, following simple rules and responding to environmental triggers. 

Despite their simplicity, their collective actions yield complex, organized behavior: building colonies, foraging for food, or defending their nest.

In this blog post, I’ll elaborate on how we can draw inspiration from the behavior of ant colonies to design a collaborative, event-driven system using AWS Serverless technologies. 

By embracing this approach, we at Essent’s Smart Charging team simplified our architecture while ensuring scalability and flexibility. 

And unlike ants, we didn’t need pheromone trails, just some EventBridge magic.

ANTS AND EVENT-DRIVEN SYSTEMS

The behavior of an ant colony mirrors the essence of an event-driven system:

• Events as triggers: In an ant colony, pheromone trails signal events, prompting specific actions from other ants. 

In AWS, events published to EventBridge act as these triggers, activating downstream processes (mostly Lambdas, in our case).

• Decentralized tasks: They don’t rely on a central authority to delegate work. Similarly, in an event-driven architecture, producers and consumers operate independently.
• Adaptability: When the environment changes, ants adjust seamlessly. With EventBridge's dynamic routing and rules, our system can adapt to new requirements with minimal rework. Like ants suddenly discovering your picnic blanket and reorganizing to raid it immediately. 

This approach aligns perfectly with AWS and serverless computing, where scalability, modularity, and flexibility take center stage.

BEFORE THE COLONY

In a previous project, we designed a system that leaned heavily on Amazon SQS and SNS. 

While this approach initially worked well, as the system grew, it started to feel like we were endlessly building SQS → Lambda or SNS → SQS → Lambda patterns.

Here’s what the setup looked like:

1. SNS for Broadcast: SNS enabled us to fan out messages to multiple subscribers, ensuring downstream systems received the updates they needed.
2. SQS for Decoupling: SQS queues acted as message buffers, allowing consumers to process events at their own pace.
3. Lambda Functions for Processing: Each SQS queue triggered a Lambda function responsible for a specific task.

While functional, the architecture became increasingly more complex 

Complexity in Routing: Managing SNS topics and subscriptions for every new integration became cumbersome as the system grew.
Scaling Frustrations: The number of connections between SNS, SQS, and Lambda functions made the architecture feel like an endlessly growing web. Every new feature required untangling and adding more layers to this web, making it harder to understand.

It worked, but it often felt like an ant carrying a humongous potato chip. It is very well possible, but unnecessarily clunky.

SIMPLIFYING THE COLONY

For our current project, we took a different approach. We started leveraging AWS EventBridge as the backbone of our architecture.

And in some way, it looks like a well-organized ant colony:

1. Dynamic Event Routing: EventBridge allows for fine-grained routing based on event patterns. Unlike SNS, where routing is tied to topics, EventBridge lets us define rules that adapt to our evolving needs. No more carrying around unwieldy potato chips!
2. Reduced Operational Overhead: By eliminating the need to manage separate SQS queues for every consumer, we reduced infrastructure complexity. Or, as ants might say, "fewer crumbs to carry".
3. Seamless Integration: EventBridge integrates effortlessly with AWS services like Lambda, DynamoDB and Kafka, making it a true hub for event-driven workflows.

DESIGNING THE COLONY

To give you a sense of how this architecture works in practice, here's a high-level overview of our setup:

1. Producers: Various microservices and systems publish events to EventBridge. Each event includes contextual information like timestamps, identifiers, and payload data.
2. Event Bus: Ants use pheromone trails to communicate and guide ants in the right direction. Our custom event bus is the pheromone trail of our system and acts as the central hub for our application's events.
3. Routing Rules: Using EventBridge rules, we route events to the appropriate targets based on their time. For example:
   
   - When a customer subscribes to our product, a subscription is created in our system and a “SubscriptionCreated” event is raised.
   - In turn, when a customer ends that subscription, a “SubscriptionEnded” event is raised.
4. Consumers: Ants have specialties and tasks. Some might be worker ants, while others might be soldier ants. Similarly, Lambda functions have certain tasks to process, tasks of a certain type. They contain a single piece of business logic and possibly trigger their own event(s).
5. Error Handling: Dead-letter queues (DLQs) capture unprocessed events, while retry policies ensure issues don’t disrupt workflows. Even ants occasionally stumble, and DLQs are their version of backup plans.
6. EventBridge Archive: Just like an ant colony keeps a history of past trails, we leverage EventBridge's archive feature to retain historical events. 

This allows us to replay past events if needed—whether for debugging, backfilling data, or recovering from failures. 

It ensures our system stays resilient even if some ants (or services) miss the original event.

TRADE-OFFS OF THE COLONY

We enjoy building our colony with EventBridge rules and tiny consumer Lambdas. 

However, it also comes with some challenges:

• Debugging event flows can be trickier than with SQS, where you can inspect messages directly. With EventBridge, structured logging, tracing, and dedicated monitoring (e.g., CloudWatch Insights) become essential for visibility.
• Handling event failures requires extra effort compared to SQS, which has built-in retry logic. We addressed this by routing failed events to a DLQ and redriving them to a queue linked back to EventBridge for reprocessing.

CONCLUSION: THE POWER OF THE COLONY

Much like an ant colony, an event-driven architecture thrives on collaboration, autonomy, and adaptability. 

By leveraging EventBridge, we streamlined our system, enabling seamless communication between services while preserving the scalability and resilience of serverless architecture.

If you're building a distributed system, consider taking inspiration from the ants. With EventBridgeas your backbone, you'll find yourself crafting a solution that's not only efficient but also elegantly simple, just like nature intended. 

And remember, if ants can achieve so much with tiny brains and pheromones, imagine what we can do!

As always, it is important to start building your application simple: EventBridge's flexibility can be overwhelming. Start with basic routing rules and expand as your needs evolve. 

Ants are incredible builders, but they wouldn’t have built Rome in a day either.