decouple commander interface from grpc

commander.go

@@ -2,19 +2,11 @@ package core
 
 import (
 	"sync"
-
-	"google.golang.org/grpc"
 )
 
-// ServiceRegistryCallback is a callback function for registering services.
-type ServiceRegistryCallback func(s *grpc.Server)
-
 // Commander is a feature that accepts commands from external source.
 type Commander interface {
 	Feature
-
-	// RegisterService registers a service into this Commander.
-	RegisterService(ServiceRegistryCallback)
 }
 
 type syncCommander struct {
@@ -22,17 +14,6 @@ type syncCommander struct {
 	Commander
 }
 
-func (c *syncCommander) RegisterService(callback ServiceRegistryCallback) {
-	c.RLock()
-	defer c.RUnlock()
-
-	if c.Commander == nil {
-		return
-	}
-
-	c.Commander.RegisterService(callback)
-}
-
 func (c *syncCommander) Start() error {
 	c.RLock()
 	defer c.RUnlock()