[feat] refactor events to use ZMQ

Before this commit, protobuf and protobuf.socketrpc were used to serialize and
transmit messages between events clients. This change implements a simpler ZMQ
client/server events mechanism that uses ZMQ sockets for transmitting messages
from clients to server and to redistribute such messages to subscribed
clients.

Closes: #6359

1 files changed, 23 insertions, 0 deletions

diff --git a/src/leap/common/events/errors.py b/src/leap/common/events/errors.py
new file mode 100644
index 0000000..58e0014
--- /dev/null
+++ b/src/leap/common/events/errors.py
@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+# errors.py
+# Copyright (C) 2015 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+
+class CallbackAlreadyRegisteredError(Exception):
+    """
+    Raised when trying to register an already registered callback.
+    """
+    pass