Design, Implement, And Test A Network Application That Maint

Design Implement And Test A Network Application That Maintains An On

Design, implement, and test a network application that maintains an online phone book. The data model for the phone book is stored in a file on the server’s computer. Clients should be able to look up a person’s phone number or add a name and number to the phone book. The server must handle multiple clients without delays. Unlike previous examples, there should be only one shared phone book accessible to all clients. The server creates this object at startup and passes it to client handlers. The deliverables include Python code for the client, server, multi-handler, and phone book modules. An extra credit option is to develop a version with a graphical user interface (GUI).

Paper For Above instruction

The development of a network application that maintains a shared online phone book involves multiple components: server, client, multi-handler, and phone book data management. This project demonstrates core concepts in network programming, concurrency, and data persistence in Python. The goal is to create an efficient multi-client system where clients can look up or add contacts to a common phone book stored on the server, which remains consistent across all client interactions and operational sessions.

Design Overview

The system architecture is based on a client-server model utilizing socket programming. The server hosts the phone book data and manages multiple client connections concurrently, ensuring that operations do not block or delay other clients. The server starts up, loads the existing phone book data from a file, and instantiates a phone book object that will represent the shared data store. This object is then passed to each client handler, which manages client requests in separate threads or processes, maintaining thread safety and data integrity.

The client application provides a simple command-line interface allowing users to request phone number lookups or add new contacts. When a client sends a request, the server processes it using the shared phone book object, updating the data or retrieving information as needed. Responses are then sent back to the client immediately, ensuring a responsive experience even with multiple clients connected simultaneously.

Implementation Details

1. The PhoneBook Class

The PhoneBook class encapsulates the contact data, supporting methods to load and save data from/to a file, search for contacts, and add new entries. To facilitate data persistence, the class handles reading from and writing to a CSV file or JSON file, depending on the preferred data format. Thread safety considerations are crucial since multiple client handlers access the shared PhoneBook object; therefore, synchronization mechanisms like locks are employed.

2. Server and Client Modules

The server module uses socket programming with threading to manage multiple clients. When a client connects, the server spawns a thread or dispatches a handler that listens for client commands such as 'LOOKUP' or 'ADD'. These commands invoke respective methods on the shared PhoneBook object, and the server responds appropriately. The server periodically saves the phone book data to the file to preserve updates.

The client module connects to the server via sockets. Users can input commands: to look up a contact, they send a 'LOOKUP' request with a name; to add a contact, they send an 'ADD' request with name and number. The client displays server responses accordingly.

3. Multi-handler Module

This module orchestrates the management of multiple client connections, ensuring each client is handled in a separate thread or asynchronous task. This design allows concurrent processing, preventing delays or bottlenecks, especially when multiple users access or modify the phone book simultaneously.

4. File Management and Data Persistence

The phone book data is loaded at server startup from a file. On each update (add or modify), the server writes the current state of the phone book back to the file, ensuring data persistence across sessions. Proper locking mechanisms prevent race conditions during read/write operations.

Extra Credit: GUI Version

Implementing a GUI can significantly enhance user experience. Using libraries like Tkinter, the client application can replace command-line input with graphical forms, buttons, and display labels for searching and adding contacts. The GUI communicates with the server similarly as the command-line client but with more user-friendly interfaces.

Conclusion

This project not only integrates multiple key programming concepts, including networking, concurrency, and data management but also provides a practical application—an online shared phone book. Proper synchronization, exception handling, and data persistence strategies are essential to ensure reliability and usability. Extending this project with a GUI makes it even more accessible and professional for end-users.

References

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