Ahmed's Blog

Backend Communication Fundamentals: Day 1 Notes

 
  • Mar 29, 2025
  • 0 views

Backend Communication Fundamentals

🔹 Section 1: Introduction

📌 Key Vocabulary

  • Multiplexing, Demultiplexing, HTTP, TCP, Multipath TCP, HTTP/2
  • Browser Demultiplexer, STB, Protocol (Rules, Properties), UDP
  • OSI Model, gRPC, Reverse Proxy, UDP Datagrams
  • Handshake, Flow Control, Congestion Control, Reliable Communication
  • HTTP/3, WebRTC, HTTPS, Zero Round Trip, Kernel
  • Single Listener, Multiple Listeners, Multiple Threads, Single Process, Multiple Processes
  • Latency, Performance, Proxies, Load Balancers, Layer 7, Reverse Proxy

📒 Key Notes

1️⃣ First Principles of Backend Communication

  • Request-Response Model: The client sends a request, the server processes it, and returns a response.
  • Push-Pull Model: The server pushes updates or the client pulls data as needed.
  • Long Polling Model: The client repeatedly requests updates at intervals.
  • Publish-Subscribe Model: Clients subscribe to topics and receive notifications when new data is available.

🔹 Section 2: Backend Communication Design Patterns

📌 Key Vocabulary

  • Protocol Buffer, RPC (Remote Procedure Call), REST, SOAP, GraphQL

📒 Key Notes

1️⃣ Request-Response Model

📌 How it works:

  1. The client sends a request.
  2. The server parses the request.
  3. The server processes the request.
  4. The server sends a response.
  5. The client parses and consumes the response.

2️⃣ Request Parsing & Processing

  • Parsing the request: Identifying the start and end of a message.
  • Processing the request: Handling various data formats (JSON, form data, HTML, etc.).

3️⃣ Where is it used?

  • Web protocols: HTTP, DNS, SSH
  • RPC communication
  • SQL & Database Protocols
  • API architectures: REST, SOAP, GraphQL

4️⃣ Anatomy of a Request-Response

  • Each request is structured according to an agreed-upon format between the client and server.
  • Defined by protocol & message structure.
  • Example HTTP request: 
    GET /resource HTTP/1.1
Host: example.com
Content-Type: application/json

5️⃣ Uploading an Image Using Request-Response

Two Approaches:

  1. Single Large Request: Upload the entire image in one request.
  2. Chunked Upload: Split the image into chunks and send them separately.
    • ✅ Allows pause & resume functionality.
    • ❌ Adds complexity compared to a single request.

6️⃣ Limitations of Request-Response

  • Not efficient for:
    • Real-time applications (e.g., chat, notifications)
    • Long-running requests
    • Handling client disconnections

7️⃣ Understanding cURL Response Chunking

  • When using curl -v --trace out.txt, responses arrive in chunks due to TCP segmentation.
  • Typical chunk size: 1388 bytes (based on TCP Maximum Segment Size ≈ 1460 bytes).
  • Why 1388 bytes?
    • Standard TCP Maximum Segment Size (MSS) is 1460 bytes.
    • Some bytes are reserved for TCP headers, leaving 1388 bytes for data.
  • Who controls this?
    • The OS’s TCP stack negotiates MSS during the handshake.
    • The server may adjust chunk sizes based on network conditions.

📌 Key takeaway: TCP segmentation determines chunk sizes, not cURL or the server directly.

🔮 Next Steps

  • Explore Synchronous vs. Asynchronous Workloads.
  • Compare alternative communication patterns like WebSockets & gRPC.
  • Dive into REST vs. GraphQL vs. RPC comparisons.
  • Implement real-world examples of backend communication patterns.

📢 Stay tuned for more insights as I continue this course! 🚀

Search