an evil script from website hacker.com could not access user’s mailbox at website gmail.com.
Support real-time communication, which can avoid short polling of browser and long polling of server. It also includes a DSL for specifying on a per-resource basis, the allowable requesting domains, the types of requests, and the supported HTTP headers. rack-jsonp-middleware is a Ruby gem that includes a piece of Rack middleware that can take care of this repetition for us. The callback parameter is set to a local function defined in a previous
