Tutor Marked Exercise 1 Proxy Server Overview

Tutor Marked Exercise 1 Proxy Serveroverviewa Proxy Server Is A Netwo

Proxy server overview a proxy server is a network server that acts as a proxy for some other real server. Many websites with a firewall have a proxy server to provide a legitimate means to go through the network barrier. The proxy server thus is a mediator between the server and the clients. It forwards a client’s request to the server and relays the server’s reply to the original client. Therefore, to the client, the proxy looks like the server. To the real server, the proxy looks like a client. For this assignment, you must implement an Internet resource retriever to act as a client and to make requests to a server, including the basic Web server you have implemented.

The basic Web server's task is to deliver resources to the client. The client requests a particular resource by writing an HTTP GET (or similar) request. On receiving a legitimate request in the form of a URL path, the server should return the contents of the corresponding file so that the client can read the response from the server via the proxy server.

When networking facilities are available, the basic Web server (or any other server) can be executed on one machine and the client can be executed on another to make requests to the server. When networking facilities are not available, both the basic Web server and the client may be executed on the same machine. The client may refer to the server host by the standard name localhost.

Paper For Above instruction

Implementing a proxy server and basic web server as outlined in the task requires a comprehensive understanding of network programming, socket programming, threading, and HTTP protocol mechanics. This paper explores the core components and design considerations involved in creating a proxy server that communicates with clients and web servers, alongside a simple web server capable of serving files upon request.

The primary goal is to develop three interlinked programs: the client, the basic web server, and the proxy server. The client acts as an initiator, sending requests for resources via the proxy server, which in turn relays the requests to the web server. The web server responds with the requested resource or appropriate error messages if the resource is unavailable.

The proxy server plays a critical role, utilizing two socket connections: one listening for client communication, and another for forwarding requests to the target web server. Incorporating threading into the proxy server allows concurrent processing of multiple client requests and server responses, essential for maintaining efficiency and responsiveness in real-world scenarios.

For the web server, handling HTTP requests involves parsing the URL, verifying the existence of the resource on disk, and transmitting the resource's data back to the client. In cases where the resource isn't available, appropriate HTTP error codes, such as 404 - Not Found or 403 - Bad Request, are returned. This behavior ensures compliance with standard web protocols and enhances robustness.

The client program is designed to solicit input from the user for resource URLs. For testing purposes, resource URLs such as "testfile.html" and "testfile.jpg" are recommended, along with real URLs like "ftp://ftp.us.dell.com/readme.txt" to test the proxy's versatility. Upon receiving the resource data, the client simply displays it on the screen, without rendering or interpreting HTML semantics.

Network configurations can vary; thus, the implementation must support execution on separate machines or on a single machine with 'localhost' references. This flexibility facilitates local testing and deployment in different environments.

Prior to deployment, thorough testing with predefined resources ensures the correctness of both the web server and proxy server functionalities. The testing plan should include checking resource retrievals, server error handling, and concurrent request processing. Deliverables include all source code files and a comprehensive test plan, packaged into one zipped file for submission via the Moodle platform.

References

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  • O'Reilly, T. (2005). Building Web Servers with Java. O'Reilly Media.

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