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package endpoint
import (
"context"
)
// Endpoint is the fundamental building block of servers and clients.
// It represents a single RPC method.
type Endpoint func(ctx context.Context, request interface{}) (response interface{}, err error)
// Nop is an endpoint that does nothing and returns a nil error.
// Useful for tests.
func Nop(context.Context, interface{}) (interface{}, error) { return struct{}{}, nil }
// Middleware is a chainable behavior modifier for endpoints.
type Middleware func(Endpoint) Endpoint
// Chain is a helper function for composing middlewares. Requests will
// traverse them in the order they're declared. That is, the first middleware
// is treated as the outermost middleware.
func Chain(outer Middleware, others ...Middleware) Middleware {
return func(next Endpoint) Endpoint {
for i := len(others) - 1; i >= 0; i-- { // reverse
next = others[i](next)
}
return outer(next)
}
}
// Failer may be implemented by Go kit response types that contain business
// logic error details. If Failed returns a non-nil error, the Go kit transport
// layer may interpret this as a business logic error, and may encode it
// differently than a regular, successful response.
//
// It's not necessary for your response types to implement Failer, but it may
// help for more sophisticated use cases. The addsvc example shows how Failer
// should be used by a complete application.
type Failer interface {
Failed() error
}