Move message parsing and validation

Create a message module to deal with message types and validation.

Signed-off-by: Simo Sorce <simo@redhat.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/custodia/message/common.py b/custodia/message/common.py
new file mode 100644
index 0000000..89deb59
--- /dev/null
+++ b/custodia/message/common.py
@@ -0,0 +1,55 @@
+# Copyright (C) 2015  Custodia Project Contributors - see LICENSE file
+
+
+class InvalidMessage(Exception):
+    """Invalid Message.
+
+    This exception is raised when a message cannot be parsed
+    or validated.
+    """
+    pass
+
+
+class UnknownMessageType(Exception):
+    """Unknown Message Type.
+
+    This exception is raised when a message is of an unknown
+    type.
+    """
+    pass
+
+
+class UnallowedMessage(Exception):
+    """Unallowed Message.
+
+    This exception is raise when the message type is know but
+    is not allowed.
+    """
+    pass
+
+
+class MessageHandler(object):
+
+    def __init__(self, request):
+        self.req = request
+        self.payload = None
+
+    def parse(self, msg):
+        """Parses the message.
+
+        :param req: the original request
+        :param msg: a decoded json string with the incoming message
+
+        :raises InvalidMessage: if the message cannot be parsed or validated
+        """
+
+        raise NotImplementedError
+
+    def reply(self, output):
+        """Generates a reply.
+
+        :param req: the original request
+        :param output: a json string with the stored output payload
+        """
+
+        raise NotImplementedError