func Watch() (Watcher, error) {
	return DefaultRegistry.Watch()
}
Watch the registry for updates
package registry
import (
	"errors"
)
var (
	DefaultRegistry Registry
	ErrNotFound = errors.New("service not found")
	ErrWatcherStopped = errors.New("watcher stopped")
)
const (
	WildcardDomain = "*"
	DefaultDomain = "micro"
)
type Registry interface {
	Init(...Option) error
	Options() Options
	Register(*Service, ...RegisterOption) error
	Deregister(*Service, ...DeregisterOption) error
	GetService(string, ...GetOption) ([]*Service, error)
	ListServices(...ListOption) ([]*Service, error)
	Watch(...WatchOption) (Watcher, error)
	String() string
}
type Service struct {
	Name      string            `json:"name"`
	Version   string            `json:"version"`
	Metadata  map[string]string `json:"metadata"`
	Endpoints []*Endpoint       `json:"endpoints"`
	Nodes     []*Node           `json:"nodes"`
}
type Node struct {
	Id       string            `json:"id"`
	Address  string            `json:"address"`
	Metadata map[string]string `json:"metadata"`
}
type Endpoint struct {
	Name     string            `json:"name"`
	Request  *Value            `json:"request"`
	Response *Value            `json:"response"`
	Metadata map[string]string `json:"metadata"`
}
type Value struct {
	Name   string   `json:"name"`
	Type   string   `json:"type"`
	Values []*Value `json:"values"`
}
func GetService(service string) ([]*Service, error) {
	return DefaultRegistry.GetService(service)
}
func ListServices() ([]*Service, error) {
	return DefaultRegistry.ListServices()
}