diff --git a/app/src/main/java/com/example/sprout/refactor/registration.puml b/app/src/main/java/com/example/sprout/refactor/registration.puml
new file mode 100644
index 0000000..306393a
--- /dev/null
+++ b/app/src/main/java/com/example/sprout/refactor/registration.puml
@@ -0,0 +1,60 @@
+@startuml
+
+class ModelLocator{
+    registrationRepository : RegistrationRepository
+}
+class AppCompatActivity
+interface ViewContract{
+    void startActivity()
+    void finishActivity()
+    void showShortToast(String message)
+    void showLongToast(String message)
+}
+interface LifecycleObserver
+class Repository
+class RegistrationRepository{
+    void registration(String userName)
+    accountObservable : Observable<Account>
+}
+class RegistrationService{
+    @POST Call<Account> registration(String userName)
+}
+class RegistrationActivity
+class RegistrationViewModel{
+    userName : ObservableField<String>
+    registrationRepository : RegistrationRepository
+    viewContract : ViewContract
+    observer: Observer<Account>
+    void onClickRegistration(String userName)
+    void onResume()
+    void onPause()
+}
+
+abstract class Observable<T>{
+    observers : ArrayList<Observer<T>>
+    void addObserver(Observer<T> observer)
+    void removeObserver(Observer<T> observer)
+    void notifyObservers(T t)
+    void notifyError(Throwable t)
+}
+
+abstract class Observer<T>{
+    void notify(T t)
+    void error(Throwable t)
+}
+
+ModelLocator o-- RegistrationRepository
+Repository <|-- RegistrationRepository
+Repository o-- OkHttpClient
+RegistrationViewModel o-- RegistrationRepository
+RegistrationRepository o-- RegistrationService
+
+AppCompatActivity <|-down- RegistrationActivity
+ViewContract <|.down. RegistrationActivity
+RegistrationActivity o-down- RegistrationViewModel
+LifecycleObserver <|.down. RegistrationViewModel
+RegistrationViewModel o-up- ViewContract
+
+RegistrationViewModel o-- Observer
+RegistrationRepository o-- Observable
+@enduml
\ No newline at end of file