README

Overview

A networked database application that allows users to manage customer information through a client-server architecture. The server handles data validation, persistence, and business logic, while the client provides a user-friendly command-line interface.

Features

• Customer Management: Add, find, update, and delete customer records
• Input Validation:
  • Name: 1-10 characters
  • Age: 1-120 years
  • Address: Up to 20 characters
  • Phone: Format XXX-XXXX (area codes: 394, 426, 901, 514)
• Persistent Storage: Records saved to data.txt
• Error Handling: Comprehensive validation with detailed error messages
• Database Reports: Generate formatted reports of all customers
• Network Communication: TCP socket-based client-server model

Project Structure

├── server.py          # Server implementation with database logic
├── client.py          # Client with interactive menu interface
└── data.txt           # Database file (auto-created)

Prerequisites

• Python 3.6 or higher
• No external dependencies required (uses standard library only)

Installation & Setup

1. Clone or download the project files

   # Ensure server.py and client.py are in the same directory

2. Prepare the database file (optional)

   • Create data.txt in the same directory, or
   • Let the server create it automatically on first run

Usage

Starting the Server

python server.py

The server will:

• Load existing records from data.txt
• Display any skipped records with error messages
• Listen on 0.0.0.0:9999

Running the Client

python client.py

The client will connect to 127.0.0.1:9999 and display the menu.

Menu Options

1. Find Customer - Search for a customer by name
2. Add Customer - Create a new customer record
3. Delete Customer - Remove a customer from the database
4. Update Customer Age - Modify age field
5. Update Customer Address - Modify address field
6. Update Customer Phone - Modify phone field
7. Print Report - Display all customers sorted by name
8. Exit - Close the connection

Data Format

Database File (data.txt):

John|25|123 Main St|514-1234
Jane|30||426-5678

Fields are pipe-separated (|). Empty fields are allowed except for name and age.

Validation Rules

Field	Required	Format/Constraints
Name	Yes	1-10 characters, unique (case-insensitive)
Age	Yes	Integer 1-120
Address	No	Max 20 characters
Phone	No	XXX-XXXX where XXX ∈ {394, 426, 901, 514}

Error Handling

The system provides specific error messages for:

• Invalid field formats
• Duplicate records
• Missing customers
• Database read errors
• Connection failures

Configuration

Server settings (in server.py):

HOST = '0.0.0.0'      # Listen on all interfaces
PORT = 9999           # Server port
DB_FILE = 'data.txt'  # Database filename

Client settings (in client.py):

SERVER_IP = '127.0.0.1'  # Server address
SERVER_PORT = 9999        # Server port

Example Session

Python DB Menu

1. Find customer
2. Add customer
...
Select: 2

Customer Name: Alice
Customer Age: 28
Customer Address: 456 Oak Ave
Customer Phone: 514-9999

Server response: Alice|28|456 Oak Ave|514-9999 added to database

Technical Details

• Protocol: TCP/IP with custom message format (command::param1::param2...)
• Encoding: UTF-8
• Buffer Size: 1024 bytes (client), 4096 bytes (server responses)
• Concurrency: Single-threaded, sequential client handling
• Data Structure: In-memory dictionary with case-insensitive keys

Troubleshooting

Connection Refused

• Ensure server is running before starting client
• Check firewall settings for port 9999
• Verify server IP/port configuration

Database Not Loading

• Check data.txt exists in server directory
• Verify file format (pipe-separated fields)
• Review server console for read errors

Author

Najlaa Achouhal