examples/chat: Rewrite in PDL

examples/chat/protocol.pdl

@@ -0,0 +1,48 @@
+// Error is sent by a party when the other party has done something erroneous. The
+// valid error codes are:
+// 
+//   - 0: General, unspecified error 
+// 
+// The description field, if specified, determines a human-readable error to be
+// shown to the user. The sending party must immediately close the transaction
+// after this message is sent.
+M0000 Error {
+	0000 Code        U16,
+	0001 Description ?String,
+}
+
+// Success is sent by a party when it has successfully completed a task given to it
+// by the other party. The sending party must immediately close the transaction
+// after this message is sent.
+M0001 Success {
+	
+}
+
+// Join is sent by the client when it wishes to join a room. It must begin a new
+// transaction, and that transaction will persist while the user is in that room.
+// Messages having to do with the room will be sent along this transaction. To
+// leave the room, the client must close the transaction.
+M0200 Join {
+	0000 Room     String,
+	0001 Nickname String,
+}
+
+// Chat is sent by the client when it wishes to post a message to the room. It is
+// also relayed by the server to other clients to notify them of the message. It
+// must be sent within a room transaction.
+M0300 Chat {
+	0000 Content  String,
+	0001 Nickname ?String,
+}
+
+// JoinNotify is sent by the server when another client joins the room. It must be
+// sent within a room transaction.
+M0400 JoinNotify {
+	0000 Nickname String,
+}
+
+// LeaveNotify is sent by the server when another client leaves the room. It must
+// be sent within a room transaction.
+M0401 LeaveNotify {
+	0000 Nickname String,
+}