Add files for Paxos decision system.

DecisionSystem/PaxosDecision/proposal.py

@@ -0,0 +1,32 @@
+from Messaging.messaginginterface import Message
+import umsgpack
+
+# Uses MessagePack for message transfer.
+
+class Proposal(Message):
+    ballot_number = None
+    vote = None
+
+    def __init__(self):
+        pass
+
+    def serialise(self) -> str:
+        return umsgpack.packb({"ballot": self.ballot_number, "vote": self.vote})
+
+    def deserialise(self, binary: bytearray):
+        '''
+        Deserialises a given proposal message into a proposal object.
+        '''
+        obj = umsgpack.unpackb(binary)
+        old_ballot = self.ballot_number
+        old_vote = self.vote
+        try:
+            self.ballot_number = obj['ballot']
+            self.vote = obj['vote']
+        except:
+            # Reset the values in case they have been changed.
+            self.ballot_number = old_ballot
+            self.vote = old_vote
+            print("Error: binary object is not a proposal")
+
+