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+# Client-server protocol
+
+
+
+
+
+## Phase 1: write the specification 
+
+specification:
+
+- What transport protocol do we use?
+
+  ```
+  TCP 
+  ```
+
+- How does the client find the server (addresses and ports)?
+
+  ```
+  127.0.0.1:8080    
+  
+  addresse is 127.0.0.1 and port is 8080
+  ```
+
+- Who speaks first?
+
+  ```
+  The client speak first while while the server is waiting for a request on it own side.
+  ```
+
+- What is the sequence of messages exchanged by the client and the server?
+
+  ```
+  The client will first of all ask for a connection request 
+  
+  The server will answer by connecting the client
+  
+  Then , the client will exchanged with the server by writing the todo maths operation , then reciproxly the server reply by sending the request answer.
+  
+  once the client close(EOF notification) the connection, the server is alerted and will then closed the communication.
+  ```
+
+- What happens when a message is received from the other party?
+
+  ```
+  Once the server receive the message, he will do the calculated the maths operation and send it 	back to the owner.
+  
+  The client will receive the answer the print it on the screen.
+  ```
+
+- What is the syntax of the messages? How we generate and parse them?
+
+  ​	
+
+  ```
+  Client :  >1+1
+  
+  Server:   >1+1 = 2
+  
+  We parse them through command line. The messages exchanged  are strings.
+  ```
+
+- Who closes the connection and when?
+
+  ```
+  The client can closed the connection.
+  
+  Otherwise, the server can also closed it if after a lapse of time(1min) , there is no demande
+  ```
+
+- Submit a PR
+
+
+
+## Phase 2: review 3 specifications 
+
+- Are there big differences between the specification?
+
+  ​		
+
+  ```
+  Of course , the are big differences between those specifications
+  ```
+
+- What are the common elements?
+
+  ​		
+
+  ```
+  The point 3,4,5,7 seems similar
+  ```
+
+- Are there missing or confusing elements in the specification?
+
+  ```
+  No
+  ```