Introducing Nexmo Rack Middleware

The text discusses Rack middleware, specifically Nexmo Rack, which is a customizable interface between Ruby web frameworks and application servers. To use Nexmo Rack, developers need to set up a Vonage API account and provide their signature secret and desired signing algorithm. The middleware supports both environment variables and Rails Credentials for authentication. Once credentialed, the VerifySignature functionality can be used to inspect incoming requests for signatures, verifying them if valid and returning a 403 Forbidden status otherwise. Developers can mount Nexmo Rack middleware into a Rails application or use it in a standalone Ruby application, with examples provided for both cases.