Bugfix: make the as yet unimplemented meta protocol not generate errors on the Python side.

2 files changed, 45 insertions, 20 deletions

diff --git a/server/socket.py b/server/socket.py
index bdf99bf..ae2068f 100644
--- a/server/socket.py
+++ b/server/socket.py
@@ -17,26 +17,51 @@ _sessions_to_socket = {}  # keyed by sid: what session is bound to what socket
 _transactions_to_socket = {}  # keyed by tid, used only when there is no sid available, so a request can be replied
 
 
+def handle_connect(data):
+    """The first packet is 'connect', providing the list of connected sessions to the peer (that's us)."""
+    pass
+
+
+def handle_unregister(data):
+    """When the client disconnects from the peer, but doesn't logout first,
+    leaving the possibility that it will reconnect in the same session,
+    possibly via other channel (nodejs instance)."""
+    pass
+
+
+# TODO: meta handlers implement system protocol to support horizontal scaling, implement them when it becomes relevant
+_meta_handlers = {
+    'connect': handle_connect,
+    'unregister': handle_unregister
+}
+
+
 def processIncomingPacket(receiving_socket, packet):
     logging.debug('Decoding JSON: {}'.format(packet))
     obj = json.loads(packet)
     req_type = obj.get('type')  # private (meta) requests have the 'type'
-    if req_type == 'connect':
-        return  # TODO: first packet is 'connect', providing the list of connected sessions to the peer
-
-    tid = obj.get('tid')  # transaction ID
-    if tid is None:
-        raise Exception('Transaction ID is missing from the request')
-    sid = obj.get('sid')  # session ID
-    _mapping_lock.acquire()
-    try:
-        if sid is None:
-            _transactions_to_socket[tid] = receiving_socket
+    if req_type is None:
+        # user protocol, internally map the request so response can be delivered correctly, and forward it to the higher layer
+        tid = obj.get('tid')  # transaction ID
+        if tid is None:
+            raise Exception('Transaction ID is missing from the request')
+        sid = obj.get('sid')  # session ID
+        _mapping_lock.acquire()
+        try:
+            if sid is None:
+                _transactions_to_socket[tid] = receiving_socket
+            else:
+                _sessions_to_socket[sid] = receiving_socket
+        finally:
+            _mapping_lock.release()
+        serve_request(obj)
+    else:
+        # system protocol, connection-specific meta data
+        handler = _meta_handlers.get(req_type)
+        if handler is None:
+            logging.error('Received an unknown meta packet: {}'.format(req_type))
         else:
-            _sessions_to_socket[sid] = receiving_socket
-    finally:
-        _mapping_lock.release()
-    serve_request(obj)
+            handler(obj)
 
 
 def sendPacket(tid, sid, json_obj):
diff --git a/web/main.js b/web/main.js
index a4dbf08..37729b9 100644
--- a/web/main.js
+++ b/web/main.js
@@ -443,16 +443,16 @@ var connectPython = function connectPythonFunc() {
 
     pythonClient.on('connect', function () {
         // login to the python server by sending it the list of currently handled sessions
-        var sid, sessions = [], packet;
+        var sid, sessionList = [], packet;
         logger.debug('Connection to Python established');
         for (sid in sessions) {
-            if (sessions.hasOwnProperty(sid)) {
-                sessions.push({'sid': sid, 'lastActivity': sessions[sid].lastActivity});
+            if (sessionList.hasOwnProperty(sid)) {
+                sessionList.push({'sid': sid, 'lastActivity': sessionList[sid].lastActivity});
             }
         }
         // this should/must succeed in sending right now, as it is the first write ever made on the socket
-        packet = JSON.stringify({'type': 'connect', 'sessions': sessions});
-        packet = packet.length + ':' + packet;
+        packet = JSON.stringify({'type': 'connect', 'sessions': sessionList});
+        packet = new Buffer(Buffer.byteLength(packet) + ':' + packet);
         sendPacketToPython(packet);
     });