Problem: monitor events are unversioned

Solution: add monitor event socket option

src/endpoint.hpp

@@ -0,0 +1,72 @@
+/*
+    Copyright (c) 2007-2016 Contributors as noted in the AUTHORS file
+
+    This file is part of libzmq, the ZeroMQ core engine in C++.
+
+    libzmq is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License (LGPL) as published
+    by the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    As a special exception, the Contributors give you permission to link
+    this library with independent modules to produce an executable,
+    regardless of the license terms of these independent modules, and to
+    copy and distribute the resulting executable under terms of your choice,
+    provided that you also meet, for each linked independent module, the
+    terms and conditions of the license of that module. An independent
+    module is a module which is not derived from or based on this library.
+    If you modify this library, you must extend this exception to your
+    version of the library.
+
+    libzmq 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 Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __ZMQ_ENDPOINT_HPP_INCLUDED__
+#define __ZMQ_ENDPOINT_HPP_INCLUDED__
+
+#include <string>
+
+namespace zmq
+{
+enum endpoint_type_t
+{
+    endpoint_type_none,   // a connection-less endpoint
+    endpoint_type_bind,   // a connection-oriented bind endpoint
+    endpoint_type_connect // a connection-oriented connect endpoint
+};
+
+struct endpoint_uri_pair_t
+{
+    endpoint_uri_pair_t () : local_type (endpoint_type_none) {}
+    endpoint_uri_pair_t (const std::string &local,
+                         const std::string &remote,
+                         endpoint_type_t local_type) :
+        local (local),
+        remote (remote),
+        local_type (local_type)
+    {
+    }
+
+    const std::string &identifier () const
+    {
+        return local_type == endpoint_type_bind ? local : remote;
+    }
+
+    std::string local, remote;
+    endpoint_type_t local_type;
+};
+
+endpoint_uri_pair_t
+make_unconnected_connect_endpoint_pair (const std::string &endpoint_);
+
+endpoint_uri_pair_t
+make_unconnected_bind_endpoint_pair (const std::string &endpoint_);
+}
+
+#endif