⚡ Caching Proxy CLI

A command-line interface (CLI) tool built with Java and Spring Boot that starts a caching proxy server. It forwards requests to an origin server, caches the responses in memory, and serves the cached responses for subsequent requests, improving performance and reducing network traffic.

Key Features

• Proxy Server: Starts an HTTP server on a configurable port.
• Request Forwarding: Forwards all incoming requests to a specified origin server.
• In-Memory Cache: Utilizes Caffeine for high-performance, in-memory caching to speed up repeated requests.
• Cache Status Header: Automatically adds an X-Cache: HIT or X-Cache: MISS header to all responses to indicate whether the response came from the cache or the origin server.
• Time-to-Live (TTL): The cache is configured to automatically evict items after a certain period (currently set to 1 minute).

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🛠️ Technologies

• Java 17+
• Spring Boot 3
• Spring WebFlux (for non-blocking, reactive I/O)
• Spring Cache Abstraction
• Caffeine Cache (in-memory cache implementation)
• Picocli (for creating the command-line interface)
• Maven (for dependency management and build)

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Prerequisites

Before you begin, ensure you have the following software installed:

• Java Development Kit (JDK) - Version 17 or higher.
• Apache Maven - Version 3.6 or higher.

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How to Build (Generate the Executable)

To compile the project and package everything into a single executable .jar file, navigate to the project's root directory and run the following command in your terminal:

mvn clean package

This command will clean any previous builds, compile the code, run tests, and create the file caching-proxy-0.0.1-SNAPSHOT.jar inside the target/ directory.

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🚀 Run and Use

The tool has two main commands.

1. Starting the Proxy Server

This command starts the server and keeps it running to handle requests.

Syntax:

java -jar target/caching-proxy-0.0.1-SNAPSHOT.jar --port <port_number> --origin <origin_url>

Example Used:

java -jar target/caching-proxy-0.0.1-SNAPSHOT.jar --port 3000 --origin https://dummyjson.com

The server will start on port 3000 and will forward all requests to https://dummyjson.com. The terminal will block, which indicates the server is up and running.

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Example Testing Workflow

After starting the server, open a new terminal to test the cache functionality.

1. First Request (Cache Miss): Make a request for a product. The response should include the X-Cache: MISS header.

curl -i http://localhost:3000/products/1

HTTP/1.1 200 OK
...
X-Cache: MISS
Content-Type: application/json; charset=utf-8
...

{"id":1,"title":"iPhone 9", ...}

2. Second Request (Cache Hit): Request the same product again. The response will be almost instantaneous, and the header will indicate a HIT.

curl -i http://localhost:3000/products/1

HTTP/1.1 200 OK
...
X-Cache: HIT
Content-Type: application/json; charset=utf-8
...

{"id":1,"title":"iPhone 9", ...}