add simple rpc helper

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

ryu/lib/rpc.py

@@ -0,0 +1,37 @@
+import msgpack
+
+
+class RpcMessage(object):
+    REQUEST = 0
+    RESPONSE = 1
+    NOTIFY = 2
+
+
+class RpcSession(object):
+    def __init__(self):
+        super(RpcSession, self).__init__()
+        self._packer = msgpack.Packer()
+        self._unpacker = msgpack.Unpacker()
+        self._next_msgid = 0
+
+    def _create_msgid(self):
+        this_id = self._next_msgid
+        self._next_msgid += 1
+        return this_id
+
+    def create_request(self, method, params):
+        msgid = self._create_msgid()
+        return self._packer.pack([RpcMessage.REQUEST, msgid, method, params])
+
+    def create_response(self, msgid, error, result):
+        return self._packer.pack([RpcMessage.RESPONSE, msgid, error, result])
+
+    def create_notification(self, method, params):
+        return self._packer.pack([RpcMessage.NOTIFY, method, params])
+
+    def get_messages(self, data):
+        self._unpacker.feed(data)
+        messages = []
+        for msg in self._unpacker:
+            messages.append(msg)
+        return messages