4.2 — Design an Application Architecture

Hands-On: Configure Service Bus with Topics and Subscriptions

Step 1: Create Service Bus Namespace

1. Navigate to Service Bus > Create
2. Configure namespace name, pricing tier: Standard (topics) or Premium (VNet, private endpoint)
3. Review and create

Step 2: Create Topic and Subscriptions

1. Open Service Bus namespace > Topics > + Topic
2. Name: order-events, max size: 1 GB, TTL: 14 days
3. Click topic > Subscriptions > + Subscription
4. Create subscriptions: billing-service, inventory-service, notification-service
5. Each subscription receives an independent copy of every message published to the topic

Step 3: Create Azure API Management

1. Navigate to API Management > Create
2. Configure organization name, email, pricing tier (Developer for testing, Standard for production)
3. After creation, go to APIs > Add API > HTTP
4. Configure frontend URL and backend URL
5. Add Policy on the inbound layer:
   • Rate limiting: rate-limit-by-key at 100 calls/minute per subscription key
   • JWT validation: validate-jwt to verify OAuth 2.0 tokens
6. Test via APIM developer portal

Step 4: Configure Azure Cache for Redis

1. Navigate to Azure Cache for Redis > Create
2. Tier: Basic (dev/test), Standard (HA replica), Premium (persistence, VNet, clustering)
3. After creation, get connection string from Access keys
4. Implement cache-aside in application:

   var cached = await redis.GetAsync("product:123");
   if (cached == null) {
     var product = await db.Products.FindAsync(123);
     await redis.SetAsync("product:123", Serialize(product), TimeSpan.FromMinutes(15));
     return product;
   }
   return Deserialize(cached);
   

Step 5: Configure Event Grid Subscription

1. Navigate to target Azure resource (e.g., Storage Account)
2. Go to Events > + Event Subscription
3. Configure:
   • Event types: BlobCreated, BlobDeleted
   • Endpoint type: Azure Function, Webhook, or Service Bus
4. Save — events fire automatically when blobs are created/deleted