restore msg_id/msg_type aliases in top level of msg dict

msg_id/type must be stored in the header, as only the header/parent/content are actually sent over the wire.  But the msg_id and msg_type should remain as aliases in the top-level msg dict, for logic and 0.11 compatibility.

* docs and tests updated to match.

IPython/zmq/session.py

@@ -357,7 +357,10 b' class Session(Configurable):'
         format, which is a list of message parts.
         """
         msg = {}
-        msg['header'] = self.msg_header(msg_type) if header is None else header
+        header = self.msg_header(msg_type) if header is None else header
+        msg['header'] = header
+        msg['msg_id'] = header['msg_id']
+        msg['msg_type'] = header['msg_type']
         msg['parent_header'] = {} if parent is None else extract_header(parent)
         msg['content'] = {} if content is None else content
         sub = {} if subheader is None else subheader
@@ -669,7 +672,10 b' class Session(Configurable):'
                 raise ValueError("Invalid Signature: %r"%signature)
         if not len(msg_list) >= minlen:
             raise TypeError("malformed message, must have at least %i elements"%minlen)
-        message['header'] = self.unpack(msg_list[1])
+        header = self.unpack(msg_list[1])
+        message['header'] = header
+        message['msg_id'] = header['msg_id']
+        message['msg_type'] = header['msg_type']
         message['parent_header'] = self.unpack(msg_list[2])
         if content:
             message['content'] = self.unpack(msg_list[3])

IPython/zmq/tests/test_session.py

@@ -47,13 +47,16 b' class TestSession(SessionTestCase):'
     def test_msg(self):
         """message format"""
         msg = self.session.msg('execute')
-        thekeys = set('header parent_header content'.split())
+        thekeys = set('header parent_header content msg_type msg_id'.split())
         s = set(msg.keys())
         self.assertEquals(s, thekeys)
         self.assertTrue(isinstance(msg['content'],dict))
         self.assertTrue(isinstance(msg['header'],dict))
         self.assertTrue(isinstance(msg['parent_header'],dict))
+        self.assertTrue(isinstance(msg['msg_id'],str))
+        self.assertTrue(isinstance(msg['msg_type'],str))
         self.assertEquals(msg['header']['msg_type'], 'execute')
+        self.assertEquals(msg['msg_type'], 'execute')
 
     def test_serialize(self):
         msg = self.session.msg('execute',content=dict(a=10))
@@ -61,6 +64,8 b' class TestSession(SessionTestCase):'
         ident, msg_list = self.session.feed_identities(msg_list)
         new_msg = self.session.unserialize(msg_list)
         self.assertEquals(ident[0], b'foo')
+        self.assertEquals(new_msg['msg_id'],msg['msg_id'])
+        self.assertEquals(new_msg['msg_type'],msg['msg_type'])
         self.assertEquals(new_msg['header'],msg['header'])
         self.assertEquals(new_msg['content'],msg['content'])
         self.assertEquals(new_msg['parent_header'],msg['parent_header'])
@@ -73,6 +78,8 b' class TestSession(SessionTestCase):'
         ident, msg_list = self.session.feed_identities(socket.data)
         new_msg = self.session.unserialize(msg_list)
         self.assertEquals(ident[0], b'foo')
+        self.assertEquals(new_msg['msg_id'],msg['msg_id'])
+        self.assertEquals(new_msg['msg_type'],msg['msg_type'])
         self.assertEquals(new_msg['header'],msg['header'])
         self.assertEquals(new_msg['content'],msg['content'])
         self.assertEquals(new_msg['parent_header'],msg['parent_header'])        
@@ -89,6 +96,8 b' class TestSession(SessionTestCase):'
         ident, msg_list = self.session.feed_identities(socket.data)
         new_msg = self.session.unserialize(msg_list)
         self.assertEquals(ident[0], b'foo')
+        self.assertEquals(new_msg['msg_id'],msg['msg_id'])
+        self.assertEquals(new_msg['msg_type'],msg['msg_type'])
         self.assertEquals(new_msg['header'],msg['header'])
         self.assertEquals(new_msg['content'],msg['content'])
         self.assertEquals(new_msg['parent_header'],msg['parent_header'])        
@@ -99,6 +108,8 b' class TestSession(SessionTestCase):'
         self.session.send(socket, msg, ident=b'foo', buffers=[b'bar'])
         ident, new_msg = self.session.recv(socket)
         self.assertEquals(ident[0], b'foo')
+        self.assertEquals(new_msg['msg_id'],msg['msg_id'])
+        self.assertEquals(new_msg['msg_type'],msg['msg_type'])
         self.assertEquals(new_msg['header'],msg['header'])
         self.assertEquals(new_msg['content'],msg['content'])
         self.assertEquals(new_msg['parent_header'],msg['parent_header'])        

docs/source/development/messaging.txt

@@ -108,6 +108,10 b' generic structure::'
                     # All recognized message type strings are listed below.
                     'msg_type' : str,
          },
+      # The msg's unique identifier and type are stored in the header, but
+      # are also accessible at the top-level for convenience.
+      'msg_id' : uuid,
+      'msg_type' : str,
 
       # In a chain of messages, the header from the parent is copied so that
       # clients can track where messages come from.