1. Create greeting-api.go inside the api directory by executing the command $ mkdir api && cd api && touch greeting-api.go.
2. Copy the following content to greeting-api.go:

package main
import 
(
  "context"
  "encoding/json"
  "log"
  "strings"
  hello "../proto"
  "github.com/micro/go-micro"
  api "github.com/micro/micro/api/proto"
)
type Say struct 
{
  Client hello.SayClient
}
func (s *Say) Hello(ctx context.Context, req *api.Request, 
rsp *api.Response) error 
{
  log.Print("Received Say.Hello request - Micro Greeter API")
  name, ok := req.Get["name"]
  if ok 
  {
    response, err := s.Client.Hello
    (
      ctx, &hello.Request
      {
        Name: strings.Join(name.Values, " "),
      }
    )
    if err != nil 
    {
      return err
    }
    message, _ := json.Marshal
    (
      map[string]string
      {
        "message": response.Msg,
      }
    )
    rsp.Body = string(message)
  }
  return nil
}
func main() 
{
  service := micro.NewService
  (
    micro.Name("go.micro.api.greeter"),
  )
  service.Init()
  service.Server().Handle
  (
    service.Server().NewHandler
    (
      &Say{Client: hello.NewSayClient("go.micro.service.
      greeter", service.Client())},
    ),
  )
  if err := service.Run(); err != nil 
  {
    log.Fatal("error starting micro api : ", err)
    return
  }
}

With everything in place, the directory structure should look like the following:

3. Move to the api directory and run the program with the following command:

$ go run greeting-api.go