System Design

Kompyuter va tarmoq asoslari

System design tushunish uchun kompyuter va tarmoq asoslarini bilish shart.

Kompyuter arxitekturasi

Asosiy komponentlar

┌──────────────────────────────┐
│         CPU (Protsessor)     │ ← Hisoblashlar
├──────────────────────────────┤
│         RAM (Xotira)         │ ← Tez, vaqtinchalik
├──────────────────────────────┤
│         Disk (Storage)       │ ← Sekin, doimiy
├──────────────────────────────┤
│      Network (Tarmoq)        │ ← Aloqa
└──────────────────────────────┘

Tezlik taqqoslash

Operatsiya	Vaqt	Real hayot analogiyasi
CPU registr	1 ns	1 soniya
RAM o’qish	100 ns	1.5 minut
SSD o’qish	10 μs	2.7 soat
HDD o’qish	10 ms	4 oy
Internet	100 ms	3 yil

Xulosa: Disk va tarmoq eng sekin operatsiyalar. System design’da asosan shu ikkalasini optimize qilish kerak.

OSI Model (7 qatlam)

Tarmoq 7 ta qatlamdan iborat:

7. Application   ← HTTP, FTP (sizning ilovangiz)
6. Presentation  ← SSL/TLS, Encryption
5. Session       ← Authentication, Session
4. Transport     ← TCP, UDP (port: 80, 443)
3. Network       ← IP, Routing (IP address)
2. Data Link     ← MAC address, Ethernet
1. Physical      ← Kabel, WiFi

System design’da asosiy 3 ta:

Application (7): HTTP/HTTPS
Transport (4): TCP/UDP
Network (3): IP addressing

Client-Server modeli

Zamonaviy internet client-server modelida ishlaydi:

┌─────────┐                    ┌─────────┐
│ Client  │ ──── Request ────→ │ Server  │
│ (Phone) │                    │ (AWS)   │
│         │ ←─── Response ──── │         │
└─────────┘                    └─────────┘

Client

Foydalanuvchi qurilmasi (telefon, brauzer)
So’rov yuboradi (request)
Javobni ko’rsatadi (render)

Server

Har doim online
So’rovlarni qayta ishlaydi
Ma’lumotlarni qaytaradi

IP Address va Port

IP Address

Har bir kompyuterning internet’dagi manzili:

IPv4: 192.168.1.1 (4 milliard manzil)
IPv6: 2001:0db8:85a3::8a2e:0370:7334 (340 undecillion)

Private IP (ichki tarmoq):

192.168.x.x
10.x.x.x

Public IP (internet):

Server’ning tashqi manzili

Port

Bitta kompyuterdagi turli xil xizmatlar:

IP: 192.168.1.1
  ├─ Port 80  → HTTP (web server)
  ├─ Port 443 → HTTPS (secure web)
  ├─ Port 22  → SSH (remote access)
  ├─ Port 5432 → PostgreSQL
  └─ Port 6379 → Redis

Full address: 192.168.1.1:443

Request-Response Lifecycle

Brauzerda facebook.com yozganingizda nima bo’ladi?

1. DNS Lookup
   facebook.com → 157.240.241.35

2. TCP Connection
   Client ←→ Server (3-way handshake)

3. HTTP Request
   GET / HTTP/1.1
   Host: facebook.com

4. Server Processing
   - Database'dan ma'lumot olish
   - HTML generatsiya qilish

5. HTTP Response
   HTTP/1.1 200 OK
   Content-Type: text/html
   <html>...</html>

6. Rendering
   Brauzer HTML'ni ko'rsatadi

Vaqt: Jami ~100-500 millisekund

Latency va Throughput

Latency (Kechikish)

Bitta requestning vaqti:

Latency = 100 ms
User → [100ms] → Server → [100ms] → User

Low latency muhim: Gaming, video call, trading

Throughput (O’tkazish qobiliyati)

Soniyasiga nechta request:

Throughput = 1000 req/sec

High throughput muhim: Video streaming, file downloads

Trade-off

Ko’pincha latency va throughput o’rtasida tanlov qilish kerak:

Latency optimize: Har bir request tez (caching)
Throughput optimize: Ko’p requestlar (batching)

Bandwidth va Data Transfer

Bandwidth

Tarmoq “quvur” o’lchami:

10 Mbps  → Uy interneti
100 Mbps → Biznes internet
10 Gbps  → Data center

Data Transfer narxi

Cloud provayderlar trafik uchun pul oladi:

AWS pricing:

Ichki trafik: $0
Tashqariga: $0.09/GB

Real misollar:

1 TB video streaming = ~$90
10 TB = ~$900

Optimization: CDN va caching bilan kamaytiramiz

Protokollar

TCP (Transmission Control Protocol)

Ishonchli: paketlar yetib borishi kafolati
Tartibli: ketma-ketlik saqlanadi
Sekinroq: confirmation kutish kerak

Qachon: HTTP, Database, File transfer

UDP (User Datagram Protocol)

Tez: confirmation yo’q
Ishonchsiz: paketlar yo’qolishi mumkin
Tartibsiz: aralashishi mumkin

Qachon: Video streaming, gaming, DNS

Xulosa

Muhim tushunchalar:

Disk va tarmoq eng sekin — bu yerda optimize qiling
Client-Server — asosiy arxitektura modeli
IP va Port — manzil tizimi
Latency vs Throughput — ikkalasini balanslashtiring
TCP vs UDP — ishonchlilik vs tezlik

Keyingi dars: Internet protokollari (HTTP, DNS va boshqalar).