diff --git a/Conception.md b/Conception.md
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+++ b/Conception.md
@@ -1 +1,57 @@
-Bienvenue sur le Wiki.
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+```plantuml
+@startuml
+class User {
+    + name : string
+}
+
+User "1" --> "*" User: friends
+User "1" --> "*" Notification: notifications
+User "1" --> "*" Ask: friendRequests
+class Notification {
+    - text : string
+}
+
+interface INotifier {
+ + notify() : void
+}
+
+INotifier --|> Observer
+
+abstract class UserManager {
+    - currentUser : User
+    + deleteFriend(userId : int) : void
+    + addFriend(userId : int) : void
+    + respondToFriendRequest(requestId : int, choice : bool) : void
+    + getFriends(userId : int) : User[]
+}
+
+class Ask {
+    - fromUser : int
+    - toUser : int
+}
+
+Ask --|> Subject
+
+abstract class Subject {
+    + attach(o : Observer) : void
+    + detach(o : Observer) : void
+    + notify() : void
+}
+
+Subject "1" --> "*" Observer
+interface Observer {
+    + update() : void
+}
+
+UserManager ..> User
+UserManager o-- IUserRepository
+UserManager o-- INotifier
+
+interface IUserRepository {
+    + findByUsername(username : string) : User
+    + addUser(user : User) : bool
+}
+
+IUserRepository ..> User
+@enduml
+```
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