InstrumentingMiddleware returns a service middleware that instruments the number of integers summed and characters concatenated over the lifetime of the service.

LoggingMiddleware takes a logger as a dependency and returns a service Middleware.

New returns a basic Service with all of the expected middlewares wired in.

NewBasicService returns a naïve, stateless implementation of Service.

ErrIntOverflow protects the Add method.

ErrMaxSizeExceeded protects the Concat method.

ErrTwoZeroes is an arbitrary business rule for the Add method.

Service describes a service that adds things together.

Middleware describes a service (as opposed to endpoint) middleware.