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Lessons (25)

• VPC Endpoints, Transit Gateway and Hybrid Networking

  … redundancy Direct Connect Dedicated private link; consistent latency; takes weeks to provision VPN over Direct Connect or a …

• Graphs: BFS & DFS

  … stations are connected by lines. Some stations connect to many others; you can often reach a station by …

• Message Queues & RabbitMQ

  … producer and consumer (Node.js, amqplib) js // producer.js import amqp from "amqplib"; const connection = await amqp.connect …

• Kafka vs RabbitMQ & the Kafka Ecosystem

  … Elasticsearch, S3, Snowflake, BigQuery, MongoDB, Postgres. json { "name": "orders-cdc", "config": { "connector.class": "io.debezium.connector.postgresql.PostgresConnector …

• VPC Networking Without the Confusion

  … 10.42.0.0/16 → local local connects VPC addresses. 0.0.0.0/0 is the default …

• Design a Chat Application

  … work, preserve priority for direct/security messages, and record delivery progress. Track connected users, reconnect rate, undelivered-message …

• 10,000 Users Do Not Need 10,000 Database Connections

  A practical mental model for connection pools, database pressure, query latency and safe scaling in Node.js applications …

• What Is Apache Kafka?

  … append an event const producer = kafka.producer(); await producer.connect(); await producer.send({ topic: "orders", messages: [{ key: "customer …

• C4 Architecture Diagrams: Context, Container, Component and Code

  … Show the major things that run inside Acme Shop and how they connect. What to include For each …

• Monolith vs Microservices

  … many independent shops, each with its own staff, stockroom and opening hours, connected by shared corridors. A mall …

• L6 Production Debugging Casebook

  … See [connection pooling](./connection-pooling-and-database-pressure). 5. Post-full-GC heap remains at 70% and rises …

• AWS Databases: Choose the Right One

  … A private database is not expected to be directly reachable from your home laptop. A public IP and …

• Hexagonal Architecture (Ports & Adapters)

  … the database is at the bottom"] direction TB L1[UI] -- L2[Business] -- L3[(Database)] end subgraph Hex["Hexagonal …

• Services and Ingress: Let Traffic Find Your App

  … traffic LoadBalancer Cloud creates a public load balancer Directly expose one service NodePort Opens a port on each …

• Real-Time, Pub/Sub, Webhooks and CDC

  … and recovery A partner returns success but the connection closes before the sender sees it. Retry the same …

• Kubernetes Cluster Architecture, Simply

  … namespaces? kubectl cluster-info Which cluster am I connected to? kubectl config current-context Which cluster/context will …

• Domains, Load Balancers and HTTPS

  … Once the browser learns the endpoint address, it connects to the endpoint. This explains why a correct DNS …

• AWS Interview Questions: Clear Answers

  … It has a route to an internet gateway, but direct IPv4 internet communication also depends on a public …

• REST vs GraphQL vs gRPC

  … on one connection, and nothing is parsed from text. Limits: browsers can't call gRPC directly (you need …

• Consumers & Consumer Groups

  … offset. mermaid flowchart LR subgraph P["Partition 0"] direction LR r0[0 ✓] -- r1[1 ✓] -- r2[2 ✓] -- r3[3 …

• Frontend Security

  … default-src 'self'; script-src 'self' 'nonce-r4nd0m'; img-src 'self' https://cdn.example.com data:; connect-src …

• Event-Driven Patterns, Step Functions and Reliable Lambdas

  … tokens to pause for a human approval, and direct SDK integrations that call 200+ AWS services without a …

• Practical Project: Deploy a Real CRM App on EKS

  … The pod has credentials, reads the secret and connects to PostgreSQL. The application exhausts its database connection pool …

• AWS Messaging: Queues, Topics and Events

  … With an SNS topic connected to separate queues, email and analytics each receive their own copy. With EventBridge …

• Go Concurrency: Goroutines, Channels and Context

  … the compiler enforces direction defer close(out) // ✅ only the SENDER closes for i := range 5 { out <- i } } func …