diff --git a/Documents/proto/general/openapi.yaml b/Documents/proto/general/openapi.yaml
index 381b210..2160d74 100644
--- a/Documents/proto/general/openapi.yaml
+++ b/Documents/proto/general/openapi.yaml
@@ -652,7 +652,7 @@ paths:
           name: type
           required: false 
           schema:
-            $ref: '#components/schemas/Roles'
+            $ref: '#/components/schemas/Roles'
       responses: 
         '200':
           description: OK
@@ -1519,6 +1519,7 @@ paths:
         summary: get a list of article's data
         tags:
           - Users
+          - Guest
           - Ext (scientific articles)
         responses: 
           '200':
diff --git a/Documents/proto/messaging_extension/ERD.md b/Documents/proto/messaging_extension/ERD.md
new file mode 100644
index 0000000..0a4108c
--- /dev/null
+++ b/Documents/proto/messaging_extension/ERD.md
@@ -0,0 +1,87 @@
+# Entity relational diagram
+
+## Messaging extension 
+
+```mermaid
+%%{init: {  "er": {"fontSize": 25, "stroke": "black" }}}%%
+erDiagram
+
+%% General
+Users
+
+%% Messages
+Discussions{
+    Integer id PK
+    String name
+}
+
+Messages{
+    Integer id PK
+    Integer response FK "Messages"
+    String content
+}
+
+Discussions ||--o{ Messages: "" 
+Discussions ||--o{ Users: ""
+
+Messages o|--o{ Messages: "answers"
+
+%% Forums
+Forums{
+    Integer id PK
+    String name
+    Integer course FK "Course"
+}
+
+Topics{
+    Integer id PK
+    String subject
+    String content
+    Boolean locked
+}
+Answers{
+    Integer id PK
+    String content
+    Boolean anonymous
+    TimeStamp creation_time 
+}
+
+Polls{
+    Integer id PK
+    enum PollType
+}
+Options{
+    Integer id PK
+    String name
+}
+
+Forums ||--o{ Users: "Registered"
+Forums ||--|| Teacher: "Owner"
+Forums ||--o{ Topics: ""
+Forums ||--o{ Polls: ""
+
+Topics ||--|| Teacher: "Author"
+Topics ||--|| Users: "Author"
+Topics ||--o{ Answers: ""
+
+Polls ||--o{ Options: ""
+
+Options ||--o{ Votes : ""
+
+Votes }o--|| Users: "Voter"
+
+
+%% Appointments
+Teacher
+Appointments{
+    Integer id PK
+    Integer teacher FK "Teacher"
+    TIME sent_time
+    enum Status
+}
+
+Appointments ||--|| Users: ""
+
+```
+
+Debucquoy Anthony
diff --git a/Documents/proto/messaging_extension/Makefile b/Documents/proto/messaging_extension/Makefile
index cf0e6b4..7ba3e31 100644
--- a/Documents/proto/messaging_extension/Makefile
+++ b/Documents/proto/messaging_extension/Makefile
@@ -11,8 +11,9 @@ extension_messagerie.pdf:use_case_messagerie.tex extension_messagerie.bbl extens
 use_case_messagerie.tex: use_case_messagerie.uml
 	plantuml -tlatex:nopreamble use_case_messagerie.uml
 
-image: use_case_messagerie.uml interaction_diagram.uml
+image: use_case_messagerie.uml interaction_diagram.uml class.uml 
 	plantuml $^ 
+	mmdc -i ERD.md -o ERD.png
 
 extension_messagerie.bbl: extension_messagerie.bcf
 	biber extension_messagerie
@@ -24,6 +25,7 @@ clean:
 	latexmk -C
 	rm -f use_case_messagerie.tex
 	rm -f extension_messagerie.{bbl,run.xml}
+	rm -f class.tex
 
 run: extension_messagerie.pdf
 	xdg-open $<
diff --git a/Documents/proto/messaging_extension/class.uml b/Documents/proto/messaging_extension/class.uml
new file mode 100644
index 0000000..48ef5b9
--- /dev/null
+++ b/Documents/proto/messaging_extension/class.uml
@@ -0,0 +1,86 @@
+@startuml
+title Class diagram for Messaging extension
+
+package Messages {
+	class Message{
+		content: String
+		response: Message
+		respond(User, String)
+	}
+	class Discussion{
+		name: String
+		users: ArrayList<User>
+		invite(User)
+		sendMessage(User, String)
+	}
+	Discussion *-- Message
+}
+
+package Forums {
+	class Forum{
+		name: String
+		Owner: Teacher
+		Registered: ArrayList<User>
+		{static} createForum(Course): Forum
+		createTopic(String): Topic
+		createPoll(String, PollType, ArrayList<Option>): Poll
+	}
+	class Topic{
+		subject: String
+		author: Teacher 
+		content: String
+		answer(User, String): Answer
+		lock(Boolean)
+	}
+	class Answer{
+		author: User
+		content: String
+		anonymous: Boolean 
+		remove()
+	}
+	class Poll{
+		options: ArrayList<Option>
+		type: PollType
+		answer(User, Option): Vote
+		addOption(Option)
+	}
+	class Option{
+		name: String
+	}
+	class Vote{
+		voter: User
+	}
+	enum PollType {
+		ALLOW_NEW_OPTIONS
+		ALLOW_MULTIPLE_CHOICE
+	}
+	note "Change the behaviour of poll" as N
+
+	Forum *-l- Topic
+	Topic *-l- Answer
+
+	Topic <|-d- Poll
+	Poll *-l- Option
+	Option "1..*" -d-x Vote
+	Poll *-- Vote
+
+	Poll -- PollType
+	PollType .r. N
+
+}
+
+package Appointments{
+	class Appointment{
+		date: Date
+		teacher: Teacher
+		student: Student
+		{static} Appointment(Student, Teacher, Date)
+		accept()
+		refuse()
+		propose(Date)
+		export(): File
+	}
+}
+
+Appointments -[hidden]d- Messages
+@enduml