Core Event-Driven Concepts - project 3

Week 5 — Core Event-Driven Concepts

1. Learn (Day 1–2)

Understand:

🔹 SQS
Message queue
Stores tasks until processed
One consumer processes message
🔹 SNS
Pub/sub system
Sends same message to multiple subscribers
🔹 EventBridge
Smart event router
Filters and routes events based on rules

1. Extend Your Existing App (Day 2–3)

Start from your Phase 2 API (Orders or Users system).

Modify:

Instead of:
API → DB only
Now:
API → DB + Event Published

Example event:

{
"eventType": "ORDER_CREATED",
"orderId": "123",
"userId": "abc",
"timestamp": "..."
}

1. Add EventBridge (Day 3–4) Create: EventBridge Event Bus (custom bus) Flow: Order Lambda sends event → EventBridge Rule:

Route based on:

eventType = ORDER_CREATED

1. Create First Consumer (Day 4–5) Lambda: Email Simulation

Triggered by EventBridge

Does:

Logs email message like:

"Email sent to user for order 123"

👉 This simulates async email system

📅 Week 6 — Scale with SQS + SNS

1. Add SQS for Reliable Processing (Day 1–2) Use case:

Order processing queue

Flow:

EventBridge → SQS Queue → Lambda Consumer

Why:

Ensures no event is lost
Can retry automatically

1. Add SNS for Fan-out (Day 2–3) Use case:

One event → multiple systems

Flow:

Order Created → SNS Topic
↓ ↓ ↓
Email Analytics Logging

Each Lambda subscribes to SNS topic.

1. Build 3 Async Consumers (Day 3–4)

Create Lambdas:

📧 Email Service Lambda
📊 Analytics Lambda
🪵 Logging Lambda

Each one:

Triggered by SNS or SQS
Runs independently

1. Observability (Day 4–5)

Use:

CloudWatch logs
Event tracing

Check:

Event delivery
Lambda execution logs
Queue processing
🧠 Final Architecture (What you’ve built)

You now have:

🚀 Event-driven system:
API creates order
Event published
Multiple services react independently
🧩 Final Outcome Statement

After this phase, you can confidently say:

“I design event-driven systems using AWS services like SQS, SNS, and EventBridge to build scalable, decoupled architectures.”