This month we’re introducing PSR-15, which proposes standards for handling and responding to HTTP requests through request handlers and middleware. A request handler receives an HTTP message (see PSR-7 , processes the request, and returns a response. A middleware component processes incoming requests, often in combination with other middleware, and will perform specific actions before the receiving application handles the request. There are two github repositories for this PSR: Server Request Handlers for Middleware (http-server-handler) and HTTP Server Middleware (http-server-middleware).
by Frank Wallen