What You’ll Build

You’re building a notification system that runs automatically. When someone uploads a file to cloud storage, an email gets sent. No manual steps. No servers to keep running.

Here’s the flow:

Why This Matters

This pattern shows up everywhere in real products:

Document Management Systems

• Team uploads a contract → stakeholders get notified
• New report uploaded → manager receives email

Data Processing Pipelines

• Raw data file arrives → data team gets alert
• Processing completes → results emailed automatically

Content Management

• Image uploaded → content team notified
• Video processing done → creator gets email

Compliance & Auditing

• Sensitive file uploaded → security team alerted
• Audit log entry created → compliance officer notified

The common thread: something happens, and someone needs to know about it. That’s event-driven architecture.

Key Terms Explained

Let’s define the important concepts you’ll work with:

Event

An event is something that happens. In our case, it’s a file being uploaded.

Examples:

• File uploaded to storage bucket
• Database record created
• Message received in queue
• Timer fired at scheduled time

Key point: Events happen automatically. You don’t poll or check. The system tells you when something occurs.

Trigger

A trigger connects an event source to your code. It’s the link that says “when this event happens, run that function.”

In our system:

• Event source: Storage bucket
• Event type: Object created
• Target: Serverless function

Key point: Triggers are configured once. After that, they work automatically.

Serverless Function

Code that runs in response to events. You write the function, the cloud runs it when needed.

Characteristics:

• No server management
• Pay only when it runs
• Scales automatically
• Stateless (each run is independent)

Key point: You focus on code, not infrastructure.

Notification Service

Sends emails, SMS, or other alerts. Can be cloud-native or third-party.

Options:

• AWS SES (Simple Email Service)
• Azure Logic Apps / SendGrid
• GCP Cloud Functions + SendGrid
• Third-party: SendGrid, Mailgun, Twilio

Key point: Handles the complexity of sending reliable emails.

The Complete Workflow

Here’s what happens step by step:

1. User uploads file → File goes to storage bucket
2. Storage emits event → “Object created” event fired
3. Trigger activates → Event routed to serverless function
4. Function receives event → Gets file metadata (name, size, path)
5. Function processes → Extracts info, formats email message
6. Function sends email → Calls notification service
7. Email delivered → Recipient receives notification

Each step happens automatically. No manual intervention needed.

What Makes This “Event-Driven”

Traditional approach:

• Code runs on a schedule
• Checks if files exist
• Processes if found
• Waits, then checks again

Event-driven approach:

• File uploaded → event fires immediately
• Function runs right away
• No polling, no waiting
• More efficient, faster response

Benefits:

• Faster response time
• Lower cost (only runs when needed)
• Simpler code (no polling logic)
• Better scalability

What You’ll Learn

By the end of this tutorial:

✅ Understand event-driven architecture - How events flow through systems

✅ Work with cloud storage - Create buckets, understand events

✅ Write serverless functions - Code that runs on demand

✅ Configure triggers - Connect events to functions

✅ Send notifications - Integrate email services

✅ Debug and test - Find and fix issues

✅ Understand costs - Know what you’re paying for

Prerequisites Check

Before moving forward, make sure you have:

• Basic HTTP and JSON knowledge
• Comfort with Node.js or Python
• Cloud account (AWS, Azure, or GCP)
• Email service account (SendGrid, Mailgun, or cloud-native)

Don’t worry if you’re not an expert. We’ll explain everything as we go.

What’s Next?

In the next page, we’ll dive into the architecture. You’ll see how storage, functions, and notifications fit together. We’ll also cover prerequisites in detail and show you how to set up your cloud account.