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Bike Rental Sistem Dizaynı

Bu sualda bizdən bike rental sistem dizayn etməyimizi istəyirlər.

Requirements​

  • İstifadəçilər qeydiyyatdan keçə bilər (login/register)
  • Mobil proqramı açaraq boş olan velosipedləri rent edə bilər
  • Subscription və ya bir dəfəlik ödəniş ola bilər
  • Notification sistemi olacaq
  • Admin velosipedləri idarə edə bilər status check edə bilər

Komponentlər və Dizayn​

  • User Service - qeydiyyat, auth. və s.
  • Rent Service - clientdən sorğu bura gəlir, bu servis həm payment həm də booking işlərini idarə edir
  • Payment Service - subscription ödəmə və s. işlərə nəzarət edir
  • Bike Service - həm inventory işi görür, velosipedlərin statusu harda olduğu göstərilir
  • Notification Service - bildirşlərə nəzarət edir

High Level Detailed Arxitektura və Komponent Dizayn​

bike-rental

Komponent detayları:​

Client Layer:

  • Mobile App: İstifadəçi interfeysi, velosiped axtarışı, booking, ödəmə
  • Web Admin: Admin panel, velosiped idarəetməsi, analytics

API Gateway:

  • Rate limiting, authentication, routing, load balancing
  • SSL termination və request/response logging

Microservices:

  • User Service: Authentication, authorization, user profile management
  • Rental Service: Booking logic, rental lifecycle, availability check
  • Payment Service: Payment processing, subscription management, billing
  • Bike Service: Inventory management, location tracking, maintenance
  • Notification Service: Push notifications, SMS, email alerts
  • Analytics Service: Usage analytics, reporting, business intelligence

Sadə Class Diagram (UML)​

bike-rental

Database Table Dizayn və Aralarındakı Əlaqə​

Koda bax

Users Table​

CREATE TABLE users (
    user_id VARCHAR(36) PRIMARY KEY,
    email VARCHAR(255) UNIQUE NOT NULL,
    phone_number VARCHAR(20) UNIQUE,
    first_name VARCHAR(100) NOT NULL,
    last_name VARCHAR(100) NOT NULL,
    password_hash VARCHAR(255) NOT NULL,
    status ENUM('ACTIVE', 'INACTIVE', 'SUSPENDED') DEFAULT 'ACTIVE',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    INDEX idx_email (email),
    INDEX idx_phone (phone_number)
);

Stations Table​

CREATE TABLE stations (
    station_id VARCHAR(36) PRIMARY KEY,
    name VARCHAR(255) NOT NULL,
    latitude DECIMAL(10, 8) NOT NULL,
    longitude DECIMAL(11, 8) NOT NULL,
    address TEXT,
    capacity INTEGER NOT NULL DEFAULT 20,
    status ENUM('ACTIVE', 'MAINTENANCE', 'CLOSED') DEFAULT 'ACTIVE',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    INDEX idx_location (latitude, longitude)
);

Bikes Table​

CREATE TABLE bikes (
    bike_id VARCHAR(36) PRIMARY KEY,
    model VARCHAR(100) NOT NULL,
    type ENUM('STANDARD', 'ELECTRIC', 'PREMIUM') NOT NULL,
    status ENUM('AVAILABLE', 'RENTED', 'MAINTENANCE', 'OUT_OF_SERVICE') DEFAULT 'AVAILABLE',
    station_id VARCHAR(36),
    current_latitude DECIMAL(10, 8),
    current_longitude DECIMAL(11, 8),
    battery_level INTEGER DEFAULT 100,
    last_maintenance DATE,
    is_locked BOOLEAN DEFAULT TRUE,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    FOREIGN KEY (station_id) REFERENCES stations(station_id),
    INDEX idx_status (status),
    INDEX idx_station (station_id),
    INDEX idx_location (current_latitude, current_longitude)
);

Bookings Table​

CREATE TABLE bookings (
    booking_id VARCHAR(36) PRIMARY KEY,
    user_id VARCHAR(36) NOT NULL,
    bike_id VARCHAR(36) NOT NULL,
    start_station_id VARCHAR(36),
    end_station_id VARCHAR(36),
    start_time TIMESTAMP,
    end_time TIMESTAMP,
    status ENUM('PENDING', 'ACTIVE', 'COMPLETED', 'CANCELLED') DEFAULT 'PENDING',
    total_amount DECIMAL(10, 2),
    payment_method ENUM('CREDIT_CARD', 'SUBSCRIPTION', 'WALLET') NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (user_id) REFERENCES users(user_id),
    FOREIGN KEY (bike_id) REFERENCES bikes(bike_id),
    FOREIGN KEY (start_station_id) REFERENCES stations(station_id),
    FOREIGN KEY (end_station_id) REFERENCES stations(station_id),
    INDEX idx_user (user_id),
    INDEX idx_bike (bike_id),
    INDEX idx_status (status),
    INDEX idx_time (start_time, end_time)
);

Payments Table​

CREATE TABLE payments (
    payment_id VARCHAR(36) PRIMARY KEY,
    booking_id VARCHAR(36),
    subscription_id VARCHAR(36),
    user_id VARCHAR(36) NOT NULL,
    amount DECIMAL(10, 2) NOT NULL,
    status ENUM('PENDING', 'COMPLETED', 'FAILED', 'REFUNDED') DEFAULT 'PENDING',
    payment_method ENUM('CREDIT_CARD', 'DEBIT_CARD', 'PAYPAL', 'APPLE_PAY') NOT NULL,
    transaction_id VARCHAR(255),
    processed_at TIMESTAMP,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (booking_id) REFERENCES bookings(booking_id),
    FOREIGN KEY (user_id) REFERENCES users(user_id),
    INDEX idx_user (user_id),
    INDEX idx_status (status),
    INDEX idx_transaction (transaction_id)
);

Subscriptions Table​

CREATE TABLE subscriptions (
    subscription_id VARCHAR(36) PRIMARY KEY,
    user_id VARCHAR(36) NOT NULL,
    type ENUM('MONTHLY', 'QUARTERLY', 'YEARLY', 'UNLIMITED') NOT NULL,
    start_date DATE NOT NULL,
    end_date DATE NOT NULL,
    monthly_fee DECIMAL(8, 2) NOT NULL,
    status ENUM('ACTIVE', 'EXPIRED', 'CANCELLED') DEFAULT 'ACTIVE',
    remaining_rides INTEGER,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (user_id) REFERENCES users(user_id),
    INDEX idx_user (user_id),
    INDEX idx_status (status),
    INDEX idx_dates (start_date, end_date)
);

Notifications Table​

CREATE TABLE notifications (
    notification_id VARCHAR(36) PRIMARY KEY,
    user_id VARCHAR(36) NOT NULL,
    type ENUM('BOOKING_CONFIRMED', 'BIKE_UNLOCKED', 'PAYMENT_SUCCESSFUL', 'SUBSCRIPTION_EXPIRED', 'MAINTENANCE_ALERT') NOT NULL,
    title VARCHAR(255) NOT NULL,
    message TEXT NOT NULL,
    status ENUM('PENDING', 'SENT', 'READ', 'FAILED') DEFAULT 'PENDING',
    sent_at TIMESTAMP,
    read_at TIMESTAMP,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (user_id) REFERENCES users(user_id),
    INDEX idx_user (user_id),
    INDEX idx_status (status),
    INDEX idx_type (type)
);

Database Əlaqə Diaqramı:​

erDiagram
    USERS {
        varchar user_id PK
        varchar email UK
        varchar phone_number UK
        varchar first_name
        varchar last_name
        varchar password_hash
        enum status
        timestamp created_at
    }
    
    STATIONS {
        varchar station_id PK
        varchar name
        decimal latitude
        decimal longitude
        text address
        int capacity
        enum status
    }
    
    BIKES {
        varchar bike_id PK
        varchar model
        enum type
        enum status
        varchar station_id FK
        decimal current_latitude
        decimal current_longitude
        int battery_level
        date last_maintenance
        boolean is_locked
    }
    
    BOOKINGS {
        varchar booking_id PK
        varchar user_id FK
        varchar bike_id FK
        varchar start_station_id FK
        varchar end_station_id FK
        timestamp start_time
        timestamp end_time
        enum status
        decimal total_amount
        enum payment_method
    }
    
    PAYMENTS {
        varchar payment_id PK
        varchar booking_id FK
        varchar subscription_id FK
        varchar user_id FK
        decimal amount
        enum status
        enum payment_method
        varchar transaction_id
    }
    
%%    SUBSCRIPTIONS {
%%        varchar subscription_id PK
%%        varchar user_id FK
%%        enum type
%%        date start_date
%%        date end_date
%%        decimal monthly_fee
%%        enum status
%%        int remaining_rides
%%    }
%%    
%%    NOTIFICATIONS {
%%        varchar notification_id PK
%%        varchar user_id FK
%%        enum type
%%        varchar title
%%        text message
%%        enum status
%%        timestamp sent_at
%%        timestamp read_at
%%    }
    
    USERS ||--o{ BOOKINGS : creates
%%    USERS ||--o{ SUBSCRIPTIONS : has
    USERS ||--o{ PAYMENTS : makes
%%    USERS ||--o{ NOTIFICATIONS : receives
    STATIONS ||--o{ BIKES : contains
    BIKES ||--o{ BOOKINGS : used_in
    BOOKINGS ||--|| PAYMENTS : has_payment
%%    SUBSCRIPTIONS ||--o{ PAYMENTS : subscription_payment
    STATIONS ||--o{ BOOKINGS : start_station
    STATIONS ||--o{ BOOKINGS : end_station

API Dizayn​

RESTful API Endpoints​

Ətraflı izah

1. User Service API​

Base URL: /api/v1/users

POST /api/v1/users/register
Content-Type: application/json
Authorization: Not required

Request Body:
{
  "email": "user@example.com",
  "password": "securePassword123",
  "firstName": "John",
  "lastName": "Doe",
  "phoneNumber": "+1234567890"
}

Response (201 Created):
{
  "userId": "uuid-string",
  "email": "user@example.com",
  "firstName": "John",
  "lastName": "Doe",
  "status": "ACTIVE",
  "createdAt": "2023-09-21T16:45:00Z"
}
POST /api/v1/users/login
Content-Type: application/json

Request Body:
{
  "email": "user@example.com",
  "password": "securePassword123"
}

Response (200 OK):
{
  "token": "jwt-token-string",
  "refreshToken": "refresh-token-string",
  "user": {
    "userId": "uuid-string",
    "email": "user@example.com",
    "firstName": "John",
    "lastName": "Doe"
  },
  "expiresIn": 3600
}
GET /api/v1/users/profile
Authorization: Bearer jwt-token

Response (200 OK):
{
  "userId": "uuid-string",
  "email": "user@example.com",
  "firstName": "John",
  "lastName": "Doe",
  "phoneNumber": "+1234567890",
  "status": "ACTIVE",
  "subscriptions": []
}

2. Bike Service API​

Base URL: /api/v1/bikes

GET /api/v1/bikes/nearby?lat=40.7128&lng=-74.0060&radius=1000
Authorization: Bearer jwt-token

Response (200 OK):
{
  "bikes": [
    {
      "bikeId": "bike-uuid-1",
      "type": "ELECTRIC",
      "batteryLevel": 85,
      "location": {
        "latitude": 40.7129,
        "longitude": -74.0058,
        "stationId": "station-uuid-1",
        "stationName": "Central Park Station"
      },
      "status": "AVAILABLE"
    }
  ],
  "totalCount": 15
}
PUT /api/v1/bikes/{bikeId}/lock
Authorization: Bearer jwt-token

Response (200 OK):
{
  "bikeId": "bike-uuid-1",
  "status": "LOCKED",
  "timestamp": "2023-09-21T16:45:00Z"
}
PUT /api/v1/bikes/{bikeId}/unlock
Authorization: Bearer jwt-token

Request Body:
{
  "bookingId": "booking-uuid-1"
}

Response (200 OK):
{
  "bikeId": "bike-uuid-1",
  "status": "UNLOCKED",
  "unlockCode": "1234",
  "timestamp": "2023-09-21T16:45:00Z"
}

3. Rental Service API​

Base URL: /api/v1/rentals

POST /api/v1/rentals/book
Authorization: Bearer jwt-token
Content-Type: application/json

Request Body:
{
  "bikeId": "bike-uuid-1",
  "startStationId": "station-uuid-1",
  "paymentMethod": "CREDIT_CARD"
}

Response (201 Created):
{
  "bookingId": "booking-uuid-1",
  "bikeId": "bike-uuid-1",
  "userId": "user-uuid-1",
  "status": "PENDING",
  "startTime": "2023-09-21T16:45:00Z",
  "estimatedCost": 5.50
}
PUT /api/v1/rentals/{bookingId}/start
Authorization: Bearer jwt-token

Response (200 OK):
{
  "bookingId": "booking-uuid-1",
  "status": "ACTIVE",
  "startTime": "2023-09-21T16:45:00Z",
  "bikeUnlockCode": "1234"
}
PUT /api/v1/rentals/{bookingId}/end
Authorization: Bearer jwt-token
Content-Type: application/json

Request Body:
{
  "endStationId": "station-uuid-2",
  "endLocation": {
    "latitude": 40.7150,
    "longitude": -74.0070
  }
}

Response (200 OK):
{
  "bookingId": "booking-uuid-1",
  "status": "COMPLETED",
  "startTime": "2023-09-21T16:45:00Z",
  "endTime": "2023-09-21T17:15:00Z",
  "duration": 30,
  "totalCost": 7.50,
  "paymentStatus": "COMPLETED"
}
GET /api/v1/rentals/history?page=1&limit=20
Authorization: Bearer jwt-token

Response (200 OK):
{
  "bookings": [
    {
      "bookingId": "booking-uuid-1",
      "bikeId": "bike-uuid-1",
      "startTime": "2023-09-21T16:45:00Z",
      "endTime": "2023-09-21T17:15:00Z",
      "duration": 30,
      "totalCost": 7.50,
      "status": "COMPLETED"
    }
  ],
  "pagination": {
    "page": 1,
    "limit": 20,
    "total": 45,
    "hasNext": true
  }
}

4. Payment Service API​

Base URL: /api/v1/payments

POST /api/v1/payments/process
Authorization: Bearer jwt-token
Content-Type: application/json

Request Body:
{
  "bookingId": "booking-uuid-1",
  "amount": 7.50,
  "paymentMethod": "CREDIT_CARD",
  "cardToken": "encrypted-card-token"
}

Response (200 OK):
{
  "paymentId": "payment-uuid-1",
  "status": "COMPLETED",
  "amount": 7.50,
  "transactionId": "txn-12345",
  "processedAt": "2023-09-21T17:16:00Z"
}
POST /api/v1/payments/subscriptions
Authorization: Bearer jwt-token
Content-Type: application/json

Request Body:
{
  "subscriptionType": "MONTHLY",
  "paymentMethod": "CREDIT_CARD",
  "cardToken": "encrypted-card-token"
}

Response (201 Created):
{
  "subscriptionId": "subscription-uuid-1",
  "type": "MONTHLY",
  "startDate": "2023-09-21",
  "endDate": "2023-10-21",
  "monthlyFee": 29.99,
  "status": "ACTIVE",
  "paymentId": "payment-uuid-2"
}

5. Station Service API​

Base URL: /api/v1/stations

GET /api/v1/stations/nearby?lat=40.7128&lng=-74.0060&radius=2000
Authorization: Bearer jwt-token

Response (200 OK):
{
  "stations": [
    {
      "stationId": "station-uuid-1",
      "name": "Central Park Station",
      "location": {
        "latitude": 40.7129,
        "longitude": -74.0058,
        "address": "Central Park West, New York, NY"
      },
      "capacity": 20,
      "availableBikes": 8,
      "availableSpaces": 12,
      "status": "ACTIVE"
    }
  ],
  "totalCount": 5
}
GET /api/v1/stations/{stationId}
Authorization: Bearer jwt-token

Response (200 OK):
{
  "stationId": "station-uuid-1",
  "name": "Central Park Station",
  "location": {
    "latitude": 40.7129,
    "longitude": -74.0058,
    "address": "Central Park West, New York, NY"
  },
  "capacity": 20,
  "availableBikes": 8,
  "bikes": [
    {
      "bikeId": "bike-uuid-1",
      "type": "ELECTRIC",
      "batteryLevel": 85,
      "status": "AVAILABLE"
    }
  ],
  "status": "ACTIVE"
}

6. Notification Service API​

Base URL: /api/v1/notifications

GET /api/v1/notifications?page=1&limit=20&status=UNREAD
Authorization: Bearer jwt-token

Response (200 OK):
{
  "notifications": [
    {
      "notificationId": "notification-uuid-1",
      "type": "BOOKING_CONFIRMED",
      "title": "Booking Confirmed",
      "message": "Your bike rental has been confirmed for Bike #1234",
      "status": "UNREAD",
      "createdAt": "2023-09-21T16:45:00Z"
    }
  ],
  "unreadCount": 3,
  "pagination": {
    "page": 1,
    "limit": 20,
    "total": 15,
    "hasNext": false
  }
}
PUT /api/v1/notifications/{notificationId}/read
Authorization: Bearer jwt-token

Response (200 OK):
{
  "notificationId": "notification-uuid-1",
  "status": "READ",
  "readAt": "2023-09-21T17:00:00Z"
}

API Authentication və Security​

JWT Token Structure:​

{
  "header": {
    "alg": "HS256",
    "typ": "JWT"
  },
  "payload": {
    "sub": "user-uuid",
    "email": "user@example.com",
    "role": "USER",
    "iat": 1695312300,
    "exp": 1695315900
  }
}

Error Response Format:​

{
  "error": {
    "code": "BIKE_NOT_AVAILABLE",
    "message": "The requested bike is not available for rental",
    "details": {
      "bikeId": "bike-uuid-1",
      "currentStatus": "MAINTENANCE"
    },
    "timestamp": "2023-09-21T16:45:00Z"
  }
}

HTTP Status Codes:​

  • 200 OK: Successful GET, PUT requests
  • 201 Created: Successful POST requests (resource creation)
  • 400 Bad Request: Invalid request parameters
  • 401 Unauthorized: Missing or invalid authentication
  • 403 Forbidden: Insufficient permissions
  • 404 Not Found: Resource not found
  • 409 Conflict: Resource conflict (e.g., bike already booked)
  • 422 Unprocessable Entity: Validation errors
  • 429 Too Many Requests: Rate limit exceeded
  • 500 Internal Server Error: Server-side errors

Rate Limiting:​

  • Authenticated users: 1000 requests/hour
  • Anonymous users: 100 requests/hour
  • Bike availability queries: 10 requests/minute per user
  • Booking operations: 5 requests/minute per user

API Versioning Strategy:​

  • URL path versioning: /api/v1/, /api/v2/
  • Header-based versioning support: API-Version: v1
  • Backward compatibility məhdudiyyəti: minimum 2 major versions

Sequence Diaqramları - Use Case Əsaslı​

Bike rental sistemindəki əsas use case-lər üçün ayrıca sequence diaqramları:

1. İstifadəçi Authentication​

sequenceDiagram
    participant U as User (Mobile App)
    participant AG as API Gateway
    participant US as User Service
    participant DB as Database

    Note over U,DB: User Authentication Flow

    U->>AG: POST /api/v1/users/login
    note right of U: {"email": "user@example.com", "password": "password123"}
    AG->>US: Forward login request
    US->>DB: Validate credentials
    DB-->>US: User data + validation result
    
    alt Valid credentials
        US->>US: Generate JWT token
        US-->>AG: JWT token + user info
        AG-->>U: Authentication success + token
    else Invalid credentials
        US-->>AG: Authentication failed
        AG-->>U: Error: Invalid credentials
    end

2. Bike Axtarışı və Kəşf​

sequenceDiagram
    participant U as User (Mobile App)
    participant AG as API Gateway
    participant BS as Bike Service
    participant SS as Station Service
    participant DB as Database

    Note over U,DB: Bike Search and Discovery Flow

    U->>AG: GET /api/v1/bikes/nearby?lat=40.7128&lng=-74.0060
    AG->>BS: Forward request with auth
    BS->>DB: Query available bikes by location
    DB-->>BS: List of available bikes
    
    BS->>SS: Get station information for bikes
    SS->>DB: Query station details
    DB-->>SS: Station data
    SS-->>BS: Station info
    
    BS-->>AG: Bikes list with station data
    AG-->>U: Available bikes near location

    U->>AG: GET /api/v1/stations/{stationId}
    AG->>SS: Get station details
    SS->>DB: Query station + bikes
    DB-->>SS: Detailed station info
    SS-->>AG: Station details with available bikes
    AG-->>U: Station information

3. Bike Booking/Rezervasiya​

sequenceDiagram
    participant U as User (Mobile App)
    participant AG as API Gateway
    participant RS as Rental Service
    participant BS as Bike Service
    participant NS as Notification Service
    participant DB as Database

    Note over U,DB: Bike Booking/Reservation Flow

    U->>AG: POST /api/v1/rentals/book
    note right of U: {"bikeId": "bike-uuid-1", "startStationId": "station-uuid-1", "paymentMethod": "CREDIT_CARD"}
    AG->>RS: Forward booking request
    
    RS->>BS: Check bike availability
    BS->>DB: Verify bike status
    DB-->>BS: Bike availability status
    
    alt Bike is available
        BS->>DB: Reserve bike (status: RESERVED)
        DB-->>BS: Bike reserved successfully
        BS-->>RS: Bike reservation confirmed
        
        RS->>DB: Create booking record (status: PENDING)
        DB-->>RS: Booking created
        
        %% Send confirmation notification
        RS->>NS: Send booking confirmation notification
        NS->>DB: Store notification
        NS-->>U: Push notification: "Bike reserved successfully"
        
        RS-->>AG: Booking confirmation
        AG-->>U: Reservation success + booking details
    else Bike not available
        BS-->>RS: Bike unavailable
        RS-->>AG: Booking failed
        AG-->>U: Error: Bike not available
    end

4. Payment İşləmə​

sequenceDiagram
    participant U as User (Mobile App)
    participant AG as API Gateway
    participant PS as Payment Service
    participant RS as Rental Service
    participant BS as Bike Service
    participant NS as Notification Service
    participant DB as Database
    participant EXT as External Payment Gateway

    Note over U,EXT: Payment Processing Flow

    U->>AG: POST /api/v1/payments/process
    note right of U: {"bookingId": "booking-uuid-1", "amount": 5.50, "paymentMethod": "CREDIT_CARD"}
    AG->>PS: Process payment request
    PS->>EXT: Process payment with external gateway
    EXT-->>PS: Payment result
    
    alt Payment successful
        PS->>DB: Update payment status (COMPLETED)
        PS->>RS: Payment confirmation
        RS->>DB: Update booking status (CONFIRMED)
        
        %% Notify user of successful payment
        PS->>NS: Send payment success notification
        NS->>DB: Store notification
        NS-->>U: Push notification: "Payment successful"
        
        PS-->>AG: Payment success
        AG-->>U: Payment confirmed
    else Payment failed
        PS->>DB: Update payment status (FAILED)
        PS->>RS: Payment failed
        RS->>BS: Release bike reservation
        BS->>DB: Update bike status (AVAILABLE)
        RS->>DB: Update booking status (CANCELLED)
        
        %% Notify user of payment failure
        PS->>NS: Send payment failure notification
        NS-->>U: Push notification: "Payment failed - reservation cancelled"
        
        PS-->>AG: Payment failed
        AG-->>U: Payment error + reservation cancelled
    end

5. Bike Rental Başlama (Unlock)​

sequenceDiagram
    participant U as User (Mobile App)
    participant AG as API Gateway
    participant RS as Rental Service
    participant BS as Bike Service
    participant NS as Notification Service
    participant DB as Database

    Note over U,DB: Bike Rental Start (Unlock) Flow

    U->>AG: PUT /api/v1/rentals/{bookingId}/start
    AG->>RS: Start rental request
    RS->>DB: Verify booking status
    DB-->>RS: Booking confirmation
    
    alt Booking is valid and confirmed
        RS->>BS: Unlock bike command
        BS->>DB: Update bike status (RENTED)
        note right of BS: IoT command sent to bike lock
        BS-->>RS: Bike unlock confirmation + code
        
        RS->>DB: Update booking (status: ACTIVE, start_time: now)
        DB-->>RS: Booking updated
        
        %% Notify successful rental start
        RS->>NS: Send rental start notification
        NS->>DB: Store notification
        NS-->>U: Push notification: "Bike unlocked - enjoy your ride!"
        
        RS-->>AG: Rental started + unlock code
        AG-->>U: Bike unlocked successfully
    else Booking invalid
        RS-->>AG: Cannot start rental
        AG-->>U: Error: Invalid booking
    end

6. Bike Rental Bitirmə (Return)​

sequenceDiagram
    participant U as User (Mobile App)
    participant AG as API Gateway
    participant RS as Rental Service
    participant BS as Bike Service
    participant PS as Payment Service
    participant NS as Notification Service
    participant DB as Database
    participant EXT as External Payment Gateway

    Note over U,EXT: Bike Rental End (Return) Flow

    U->>AG: PUT /api/v1/rentals/{bookingId}/end
    note right of U: {"endStationId": "station-uuid-2", "endLocation": {...}}
    AG->>RS: End rental request
    
    RS->>BS: Lock bike command
    BS->>DB: Update bike status (AVAILABLE) + location
    note right of BS: IoT command sent to bike lock
    BS-->>RS: Bike locked confirmation
    
    RS->>DB: Update booking (status: COMPLETED, end_time: now)
    RS->>DB: Calculate total cost based on duration
    DB-->>RS: Final booking details
    
    %% Final payment processing if needed
    alt Additional charges required
        RS->>PS: Process additional payment
        PS->>EXT: Charge additional amount
        EXT-->>PS: Payment result
        PS->>DB: Update payment record
        PS-->>RS: Final payment processed
    end
    
    %% Send completion notification
    RS->>NS: Send rental completion notification
    NS->>DB: Store notification
    NS-->>U: Push notification: "Rental completed - thank you!"
    
    RS-->>AG: Rental completion details
    AG-->>U: Rental completed successfully + final cost

7. Notification İdarəetməsi​

sequenceDiagram
    participant RS as Rental Service
    participant PS as Payment Service
    participant NS as Notification Service
    participant DB as Database
    participant U as User (Mobile App)
    participant SMS as SMS/Push Service

    Note over RS,SMS: Notification Management Flow

    alt Booking Notification
        RS->>NS: Send booking confirmation
        note right of RS: {"userId": "user-uuid", "type": "BOOKING_CONFIRMED", "message": "..."}
    else Payment Notification
        PS->>NS: Send payment notification
        note right of PS: {"userId": "user-uuid", "type": "PAYMENT_SUCCESSFUL", "message": "..."}
    end
    
    NS->>DB: Store notification record
    DB-->>NS: Notification stored
    
    NS->>SMS: Send push notification
    SMS-->>U: Push notification delivered
    
    NS->>DB: Update notification status (SENT)
    
    %% User reads notification
    U->>NS: Mark notification as read
    NS->>DB: Update notification status (READ)
    DB-->>NS: Status updated
    NS-->>U: Notification marked as read

Use Case Diaqramlarının Açıqlamaları:​

1. Authentication: İstifadəçi login prosesi və JWT token yaradılması

2. Bike Search: Yaxınlıqdakı bike-ların axtarışı və station məlumatlarının əldə edilməsi

3. Booking: Bike rezervasiya prosesi və availability check

4. Payment: Ödəmə işləmə və uğursuzluq halında rollback

5. Rental Start: Bike unlock və rental başlama

6. Rental End: Bike return, lock və final ödəmə hesablaması

7. Notifications: Sistem notification-larının idarə edilməsi

Hər use case öz məsuliyyətini daşıyır və ayrıca test edilə bilər.

Bottleneck və İnkişaf Oluna Biləcəklər​

1. Performans Bottleneck-ləri:​

Database Bottlenecks:

  • Bike location queries çox tez-tez edilir (real-time tracking)
  • Booking table-də concurrency issues ola bilər eyni bike üçün
  • User authentication queries yüksək load zamanı slow ola bilər

Həllər:

  • Redis cache istifadə edərək bike locations cache etmək
  • Database connection pooling və read replicas
  • Optimistic locking booking zamanı race conditions üçün

API Bottlenecks:

  • Peak hours-da (səhər/axşam) yüksək traffic
  • Real-time bike availability queries

Həllər:

  • Rate limiting və API throttling
  • CDN istifadə edərək static content üçün
  • Asynchronous processing message queues ilə

2. Scalability İmkanları:​

Horizontal Scaling:

  • Microservices containerization (Docker/Kubernetes)
  • Database sharding user_id və location əsasında
  • Geographic region-based deployment

Caching Strategy:

  • Redis Cluster bike availability üçün
  • Application-level caching frequently accessed data
  • Browser caching mobile app üçün

Event-Driven Architecture:

  • Kafka/RabbitMQ messaging between services
  • Event sourcing critical business events üçün
  • CQRS pattern read/write operations ayırmaq üçün

3. Monitoring və Alerting:​

Key Metrics:

  • Response time hər service üçün
  • Database connection pool usage
  • Cache hit/miss ratios
  • Business metrics: booking success rate, payment failures

Alerting:

  • High error rates
  • Database connection exhaustion
  • Low bike availability specific locations-da
  • Payment gateway failures

4. Security Enhancements:​

  • JWT token expiration və refresh mechanism
  • API rate limiting per user/IP
  • Encrypted bike GPS data transmission
  • PCI DSS compliance payment data üçün
  • Regular security audits və penetration testing

5. Future Enhancements:​

AI/ML Features:

  • Predictive analytics bike demand forecasting
  • Dynamic pricing based on demand/supply
  • Optimal bike redistribution algorithms
  • User behavior analysis və personalized recommendations

IoT Integration:

  • Smart locks remote control
  • Real-time bike health monitoring
  • Automated maintenance scheduling
  • Weather-based availability predictions

Advanced Features:

  • Integration navigation apps ilə (Google Maps, Waze)
  • Social features - ride sharing, leaderboards
  • Corporate subscription packages
  • Integration public transportation ilə