Proxies

Some are excerpts from Grokking System Design

The Concept

A proxy server is an intermediary piece of hardware/software that sits between the client and the back-end server. It receives requests from clients and relays them to the origin servers.

Usage

Typically, proxies are used to filter requests or log requests, or sometimes transform requests (by adding/removing headers, encrypting/decrypting, or compression).

Another advantage of a proxy server is that its cache can serve a lot of requests.

Coordinating requests from multiple servers and can be used to optimize request traffic from a system-wide perspective. e.g. collapse the same (or similar) data access requests into one request and then return the single result to the user; this scheme is called collapsed forwarding.