Client and server

.gitignore

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+.idea/
 target/
 pom.xml.tag
 pom.xml.releaseBackup

Teaching-HEIGVD-RES-2020-Exercise-Protocol-Design.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

specs/jul0105/PROTOCOL.md

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+# Specification
+
+## 1. What transport protocol do we use?
+
+We use TCP.
+
+## 2. How does the client find the server (addresses and ports)?
+
+The port used is 25566. 
+
+The IP address is dynamic.
+
+## 3. Who speaks first?
+
+The client initialize the communication
+
+## 4. What is the sequence of messages exchanged by the client and the server? (flow)
+
+client open connection
+
+**client -> server** : handshake
+
+**server -> client** : handshake response
+
+**client -> server** : send operation
+
+**server -> client** : send result or error
+
+client close connection
+
+## 5. What happens when a message is received from the other party? (semantics)
+
+**Server :**
+
+1. **Receive handshake** : 
+   1. Send handshake response with supported operations
+2. **Receive operation** : 
+   1. Check if the operation is supported
+   2. Execute calculation 
+   3. Send result or error if any
+
+**Client :**
+
+1. **Receive handshake response** : 
+   1. Check if desired operation is supported by the server
+   2. If yes, send operation
+   3. If no, close connection
+2. **Receive operation result or error** :
+   1. Print result or error if any
+
+## 6. What is the syntax of the messages? How we generate and parse them? (syntax)
+
+**handshake :**
+
+```
+CALC CLIENT
+```
+
+
+
+**handshake response :**
+
+```
+CALC SERVER;<SUPPORTED OPERATIONS>
+```
+
+Example : 
+
+```
+CALC SERVER;ADD SUB MUL DIV
+```
+
+
+
+**send operation :**
+
+```
+<OPERAND 1> <OPERATION> <OPERAND 2>
+```
+
+Example :
+
+```
+6 + 4
+5 - 1
+2 * 4
+10 / 0
+```
+
+
+
+**send result or error :**
+
+If the operation is correct :
+
+```
+RES <RESULT>
+```
+
+If the operation is incorrect or there is an error :
+
+```
+ERR <DESCRIPTION>
+```
+
+Example :
+
+```
+RES 10
+RES 4
+RES 8
+ERR Cannot divide by 0
+```
+
+
+
+## 6. Who closes the connection and when?
+
+The client close the connection when he receive the response of the operation from the server.