Objectives To Understand Client-Server Communication Via SOC

Objectives To Understand Client Server Communication Via Sockets T

Develop a multithreaded web server and a simple web client that communicate using HTTP. The server must handle multiple concurrent requests, respond with appropriate HTTP status codes, and serve requested pages or error messages. The client connects to the server, requests a page, and displays the response content and status. Both programs should be command-line driven with specified syntax, and the server should listen on a configurable port (default 8080).

The server should log request headers for debugging and serve default pages when no specific page is requested. The client should log received responses, extract message status and content, and handle default page requests smoothly. Both implementations should be well-documented, and source code must be submitted as a zipped file with explicit instructions and identification details. Adherence to socket programming practices, multi-threading, and HTTP message formats as discussed in textbook chapters is required. Proper validation of HTTP requests and server responses is essential to meet project specifications.

Paper For Above instruction

Introduction

The development of a multi-threaded web server and corresponding client application is pivotal in understanding fundamental networking principles, particularly the client-server architecture and socket programming. This project encapsulates core concepts such as handling multiple requests concurrently, processing HTTP GET messages, and managing TCP connections using sockets. By implementing these components, students gain practical insights into the foundational protocols that underpin web communication, including the structure of HTTP messages and the mechanics of request-response cycles.

Design and Implementation of the Web Server

The web server is designed to be multi-threaded to efficiently manage multiple simultaneous HTTP requests. It listens on a specified port—defaulting to 8080 unless overridden via command-line arguments—and employs a server socket to accept incoming connection requests. For each request, it spawns a new thread, ensuring the server remains responsive. The server processes HTTP GET requests by parsing request headers, extracting the requested resource's path, and determining if the file exists within the server's directory.

If the requested resource is available, the server responds with an HTTP 200 OK status alongside the contents of the file. If not, it returns appropriate error messages such as 404 Not Found or 400 Bad Request. The server logs request headers for each request to facilitate debugging and analysis. After serving each request, it closes the individual connection, adhering to the standard HTTP/1.1 protocol, which allows persistent connections but for simplicity, this implementation opts to close after each transaction.

Implementation specifics involve utilizing Java’s `ServerSocket` and `Socket` classes or Python’s `socket` module. Multithreading is managed through threading libraries like `Thread` in Java or the `threading` module in Python. In handling HTTP requests, the server must parse headers accurately, validate request formats, and serve the correct content type for HTML files. The server also serves a default page — typically "index.htm" — when no specific resource is specified.

Development of the Web Client

The web client is a lightweight application that creates a socket connection to the server, specified via command-line parameters such as IP address or hostname, port number, and file path. It constructs and sends an HTTP GET request for the specified resource. Upon receiving the server response, the client extracts the status line to determine success or failure and then displays the content of the response body, which contains the requested page or error message.

The client logs server responses, enabling users to trace the complete request and response cycle. It must handle default file requests when no specific file is mentioned, defaulting to "index.htm." The implementation uses socket programming constructs suitable to the language of choice (Java or Python) and ensures robustness in handling server responses, including parsing HTTP headers and content correctly.

Technical Challenges and Considerations

Implementing multithreading requires careful synchronization to avoid race conditions and resource conflicts, especially when logging request headers or serving files. Handling HTTP message parsing demands attention to the protocol’s syntax, including line terminators, headers, and message bodies. Proper error handling is critical, ensuring that malformed requests or server errors do not crash the system and that informative HTTP error responses are correctly generated.

Security considerations are minimal in this project but can include validating file paths to prevent directory traversal attacks and ensuring proper handling of special characters in URLs. Efficiency can be enhanced via connection reuse techniques, but for educational purposes, the focus remains on fundamental socket operations and correct protocol handling.

Conclusion

The comprehensive development of a multi-threaded HTTP server along with a simple client illuminates vital networking principles and protocols. This exercise concretizes the understanding of socket programming, threading, and the HTTP protocol, forming a foundational skill set for advanced web application development. Proper implementation, debugging, and documentation are essential to produce a reliable, standards-compliant system demonstrating core server-client communication skills.

References

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• Odersky, M. (2004). Programming in Scala. Artima Inc.
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• Gonçalves, S., & Sharkey, P. (2016). HTTP Protocol and Web Development. University publications.