Node Caching Proxy

An HTTP server that behaves as a transparent caching reverse proxy for incoming GET requests using Node.js.

How It Works

1. Proxy server: The proxy accepts incoming HTTP GET requests and forwards them on to a destination host server. It fowards back server responses to the client and caches the response for retrieval in future requests of the same resource, done in lieu of a call to the host server.

2. Caching Layer: A configurable in-memory LRU (least recently used) cache is built into the proxy and uses a hash map for O(1) lookup time of cached entries. It stores up to 50 entries or 5MB of memory by default and has the following methods:

• add
• get
• removeOldest
• remove
• clearAll
• hasKey
• isFull
• isEmpty

A doubly linked list is used for efficient entry insertion and removal. Newest entries are added to tail, while oldest entries are removed from head in O(1) time as memory and size limits are reached. Individual entries also emit an expired event and are cleared from cache after 1 hour by default.

3. Host server: The host server is the destination where the proxy forwards requests and is set to listen to requests on port 4000. It sends back a basic text response for demo purposes.

How to Install

1. Install Node.js.

2. Clone the node-cache-proxy repository link .

$ git clone https://github.com/cl2205/cache-proxy-node.git
$ cd cache-proxy-node

Launching

The proxy can be launched locally by running node proxy in the root directory.

$ node proxy 

In a new terminal window, launch the host server locally by running node server in root.

$ node server

Now, you can make GET requests to http://localhost:3000 using curl, a browser, or POSTMAN, etc.

Example:

$ curl http://localhost:3000

will return Some static content

The response is now stored in the proxy's in-memory cache and will be retrieved from the cache in future requests, until cache is full or the entry expires.

Testing

Mocha tests are run against a separate test proxy and test host server.

Run npm install to install test dependencies and npm test to run tests for this project. It's that simple :)

$ npm install
$ npm test