Fixed ICE-7584 - discovery plugins now send multicast datagrams on all interfaces

11 files changed, 438 insertions, 357 deletions

diff --git a/java/src/Ice/src/main/java/com/zeroc/IceInternal/Network.java b/java/src/Ice/src/main/java/com/zeroc/IceInternal/Network.java
index 7e29515406d..cb56f0bb9e1 100644
--- a/java/src/Ice/src/main/java/com/zeroc/IceInternal/Network.java
+++ b/java/src/Ice/src/main/java/com/zeroc/IceInternal/Network.java
@@ -303,7 +303,7 @@ public final class Network
         try
         {
             java.util.Set<java.net.NetworkInterface> interfaces = new java.util.HashSet<>();
-            for(String address : getInterfacesForMulticast(intf, group))
+            for(String address : getInterfacesForMulticast(intf, getProtocolSupport(group)))
             {
                 java.net.NetworkInterface intf2 = getInterface(address);
                 if(!interfaces.contains(intf2))
@@ -325,7 +325,7 @@ public final class Network
         try
         {
             java.util.Set<java.net.NetworkInterface> interfaces = new java.util.HashSet<>();
-            for(String address : getInterfacesForMulticast(intf, group))
+            for(String address : getInterfacesForMulticast(intf, getProtocolSupport(group)))
             {
                 java.net.NetworkInterface intf2 = getInterface(address);
                 if(!interfaces.contains(intf2))
@@ -1081,10 +1081,9 @@ public final class Network
         return hosts;
     }
 
-    public static java.util.ArrayList<String>
-    getInterfacesForMulticast(String intf, java.net.InetSocketAddress mcastAddr)
+    public static java.util.List<String>
+    getInterfacesForMulticast(String intf, int protocolSupport)
     {
-        int protocolSupport = getProtocolSupport(mcastAddr);
         java.util.ArrayList<String> interfaces = new java.util.ArrayList<>();
         if(isWildcard(intf))
         {
diff --git a/java/src/Ice/src/main/java/com/zeroc/IceInternal/PropertyNames.java b/java/src/Ice/src/main/java/com/zeroc/IceInternal/PropertyNames.java
index 6d1273b8793..eb3319e9b46 100644
--- a/java/src/Ice/src/main/java/com/zeroc/IceInternal/PropertyNames.java
+++ b/java/src/Ice/src/main/java/com/zeroc/IceInternal/PropertyNames.java
@@ -6,7 +6,7 @@
 // ICE_LICENSE file included in this distribution.
 //
 // **********************************************************************
-// Generated by makeprops.py from file ..\config\PropertyNames.xml, Fri Feb 24 18:49:18 2017
+// Generated by makeprops.py from file ./config/PropertyNames.xml, Tue Feb 28 15:01:12 2017
 
 // IMPORTANT: Do not edit this file -- any edits made here will be lost!
 
@@ -504,6 +504,43 @@ public final class PropertyNames
         new Property("IceGridAdmin\\.Discovery\\.Reply\\.ThreadPool\\.ThreadIdleTime", false, null),
         new Property("IceGridAdmin\\.Discovery\\.Reply\\.ThreadPool\\.ThreadPriority", false, null),
         new Property("IceGridAdmin\\.Discovery\\.Reply\\.MessageSizeMax", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ACM\\.Timeout", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ACM\\.Heartbeat", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ACM\\.Close", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ACM", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.AdapterId", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Endpoints", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Locator\\.EndpointSelection", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Locator\\.ConnectionCached", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Locator\\.PreferSecure", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Locator\\.LocatorCacheTimeout", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Locator\\.InvocationTimeout", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Locator\\.Locator", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Locator\\.Router", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Locator\\.CollocationOptimized", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Locator\\.Context\\.[^\\s]+", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Locator", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.PublishedEndpoints", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ReplicaGroupId", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Router\\.EndpointSelection", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Router\\.ConnectionCached", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Router\\.PreferSecure", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Router\\.LocatorCacheTimeout", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Router\\.InvocationTimeout", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Router\\.Locator", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Router\\.Router", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Router\\.CollocationOptimized", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Router\\.Context\\.[^\\s]+", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.Router", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ProxyOptions", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ThreadPool\\.Size", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ThreadPool\\.SizeMax", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ThreadPool\\.SizeWarn", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ThreadPool\\.StackSize", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ThreadPool\\.Serialize", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ThreadPool\\.ThreadIdleTime", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.ThreadPool\\.ThreadPriority", false, null),
+        new Property("IceGridAdmin\\.Discovery\\.Locator\\.MessageSizeMax", false, null),
         new Property("IceGridAdmin\\.Trace\\.Observers", false, null),
         new Property("IceGridAdmin\\.Trace\\.SaveToRegistry", false, null),
         null
diff --git a/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpMulticastClientTransceiver.java b/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpMulticastClientTransceiver.java
index e3edc69d4b5..2390cea50a1 100644
--- a/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpMulticastClientTransceiver.java
+++ b/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpMulticastClientTransceiver.java
@@ -161,7 +161,8 @@ final class UdpMulticastClientTransceiver implements Transceiver
     public String toDetailedString()
     {
         StringBuilder s = new StringBuilder(toString());
-        java.util.List<String> intfs = Network.getInterfacesForMulticast(_mcastInterface, _addr);
+        java.util.List<String> intfs = Network.getInterfacesForMulticast(_mcastInterface,
+                                                                         Network.getProtocolSupport(_addr));
         if(!intfs.isEmpty())
         {
             s.append("\nlocal interfaces = ");
diff --git a/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpMulticastServerTransceiver.java b/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpMulticastServerTransceiver.java
index 8c7b462e89e..bfcc1c11060 100644
--- a/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpMulticastServerTransceiver.java
+++ b/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpMulticastServerTransceiver.java
@@ -169,7 +169,8 @@ final class UdpMulticastServerTransceiver implements Transceiver
     public String toDetailedString()
     {
         StringBuilder s = new StringBuilder(toString());
-        java.util.List<String> intfs = Network.getInterfacesForMulticast(_mcastInterface, _addr);
+        java.util.List<String> intfs = Network.getInterfacesForMulticast(_mcastInterface,
+                                                                         Network.getProtocolSupport(_addr));
         if(!intfs.isEmpty())
         {
             s.append("\nlocal interfaces = ");
diff --git a/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpTransceiver.java b/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpTransceiver.java
index 491e6c0b7ee..8f6d5683251 100644
--- a/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpTransceiver.java
+++ b/java/src/Ice/src/main/java/com/zeroc/IceInternal/UdpTransceiver.java
@@ -290,7 +290,7 @@ final class UdpTransceiver implements Transceiver
         }
         else
         {
-            intfs = Network.getInterfacesForMulticast(_mcastInterface, _mcastAddr);
+            intfs = Network.getInterfacesForMulticast(_mcastInterface, Network.getProtocolSupport(_mcastAddr));
         }
         if(!intfs.isEmpty())
         {
diff --git a/java/src/IceDiscovery/src/main/java/com/zeroc/IceDiscovery/LookupI.java b/java/src/IceDiscovery/src/main/java/com/zeroc/IceDiscovery/LookupI.java
index 5e3910d4aef..ac99857d3ae 100644
--- a/java/src/IceDiscovery/src/main/java/com/zeroc/IceDiscovery/LookupI.java
+++ b/java/src/IceDiscovery/src/main/java/com/zeroc/IceDiscovery/LookupI.java
@@ -172,17 +172,78 @@ class LookupI implements Lookup
     public LookupI(LocatorRegistryI registry, LookupPrx lookup, com.zeroc.Ice.Properties properties)
     {
         _registry = registry;
-        _lookup = lookup;
         _timeout = properties.getPropertyAsIntWithDefault("IceDiscovery.Timeout", 300);
         _retryCount = properties.getPropertyAsIntWithDefault("IceDiscovery.RetryCount", 3);
         _latencyMultiplier = properties.getPropertyAsIntWithDefault("IceDiscovery.LatencyMultiplier", 1);
         _domainId = properties.getProperty("IceDiscovery.DomainId");
         _timer = com.zeroc.IceInternal.Util.getInstance(lookup.ice_getCommunicator()).timer();
+
+        try
+        {
+            lookup.ice_getConnection();
+        }
+        catch(com.zeroc.Ice.LocalException ex)
+        {
+            StringBuilder b = new StringBuilder();
+            b.append("IceDiscovery is unable to establish a multicast connection:\n");
+            b.append("proxy = ");
+            b.append(lookup.toString());
+            b.append('\n');
+            b.append(ex.toString());
+            throw new com.zeroc.Ice.PluginInitializationException(b.toString());
+        }
+
+        //
+        // Create one lookup proxy per endpoint from the given proxy. We want to send a multicast
+        // datagram on each endpoint.
+        //
+        com.zeroc.Ice.Endpoint[] single = new com.zeroc.Ice.Endpoint[1];
+        for(com.zeroc.Ice.Endpoint endpt : lookup.ice_getEndpoints())
+        {
+            try
+            {
+                single[0] = endpt;
+                LookupPrx l = (LookupPrx)lookup.ice_endpoints(single);
+                l.ice_getConnection();
+                _lookup.put(l, null);
+            }
+            catch(com.zeroc.Ice.LocalException ex)
+            {
+            }
+        }
+        assert(!_lookup.isEmpty());
     }
 
     void setLookupReply(LookupReplyPrx lookupReply)
     {
-        _lookupReply = lookupReply;
+        //
+        // Use a lookup reply proxy whose adress matches the interface used to send multicast datagrams.
+        //
+        com.zeroc.Ice.Endpoint[] single = new com.zeroc.Ice.Endpoint[1];
+        for(Map.Entry<LookupPrx, LookupReplyPrx> entry : _lookup.entrySet())
+        {
+            com.zeroc.Ice.UDPEndpointInfo info =
+                (com.zeroc.Ice.UDPEndpointInfo)entry.getKey().ice_getEndpoints()[0].getInfo();
+            if(!info.mcastInterface.isEmpty())
+            {
+                for(com.zeroc.Ice.Endpoint q : lookupReply.ice_getEndpoints())
+                {
+                    com.zeroc.Ice.EndpointInfo r = q.getInfo();
+                    if(r instanceof com.zeroc.Ice.IPEndpointInfo &&
+                       ((com.zeroc.Ice.IPEndpointInfo)r).host.equals(info.mcastInterface))
+                    {
+                        single[0] = q;
+                        entry.setValue((LookupReplyPrx)lookupReply.ice_endpoints(single));
+                    }
+                }
+            }
+
+            if(entry.getValue() == null)
+            {
+                // Fallback: just use the given lookup reply proxy if no matching endpoint found.
+                entry.setValue(lookupReply);
+            }
+        }
     }
 
     @Override
@@ -250,7 +311,10 @@ class LookupI implements Lookup
         {
             try
             {
-                _lookup.findObjectByIdAsync(_domainId, id, _lookupReply);
+                for(Map.Entry<LookupPrx, LookupReplyPrx> entry : _lookup.entrySet())
+                {
+                    entry.getKey().findObjectByIdAsync(_domainId, id, entry.getValue());
+                }
                 request.scheduleTimer(_timeout);
             }
             catch(com.zeroc.Ice.LocalException ex)
@@ -274,7 +338,10 @@ class LookupI implements Lookup
         {
             try
             {
-                _lookup.findAdapterByIdAsync(_domainId, adapterId, _lookupReply);
+                for(Map.Entry<LookupPrx, LookupReplyPrx> entry : _lookup.entrySet())
+                {
+                    entry.getKey().findAdapterByIdAsync(_domainId, adapterId, entry.getValue());
+                }
                 request.scheduleTimer(_timeout);
             }
             catch(com.zeroc.Ice.LocalException ex)
@@ -325,7 +392,10 @@ class LookupI implements Lookup
         {
             try
             {
-                _lookup.findObjectByIdAsync(_domainId, request.getId(), _lookupReply);
+                for(Map.Entry<LookupPrx, LookupReplyPrx> entry : _lookup.entrySet())
+                {
+                    entry.getKey().findObjectByIdAsync(_domainId, request.getId(), entry.getValue());
+                }
                 request.scheduleTimer(_timeout);
                 return;
             }
@@ -350,7 +420,10 @@ class LookupI implements Lookup
         {
             try
             {
-                _lookup.findAdapterByIdAsync(_domainId, request.getId(), _lookupReply);
+                for(Map.Entry<LookupPrx, LookupReplyPrx> entry : _lookup.entrySet())
+                {
+                    entry.getKey().findAdapterByIdAsync(_domainId, request.getId(), entry.getValue());
+                }
                 request.scheduleTimer(_timeout);
                 return;
             }
@@ -364,8 +437,7 @@ class LookupI implements Lookup
     }
 
     private LocatorRegistryI _registry;
-    private final LookupPrx _lookup;
-    private LookupReplyPrx _lookupReply;
+    private java.util.Map<LookupPrx, LookupReplyPrx> _lookup = new java.util.HashMap<>();
     private final int _timeout;
     private final int _retryCount;
     private final int _latencyMultiplier;
diff --git a/java/src/IceDiscovery/src/main/java/com/zeroc/IceDiscovery/PluginI.java b/java/src/IceDiscovery/src/main/java/com/zeroc/IceDiscovery/PluginI.java
index 9b52edf963b..46bed9f0ee8 100644
--- a/java/src/IceDiscovery/src/main/java/com/zeroc/IceDiscovery/PluginI.java
+++ b/java/src/IceDiscovery/src/main/java/com/zeroc/IceDiscovery/PluginI.java
@@ -9,6 +9,8 @@
 
 package com.zeroc.IceDiscovery;
 
+import com.zeroc.IceInternal.Network;
+
 public class PluginI implements com.zeroc.Ice.Plugin
 {
     public PluginI(com.zeroc.Ice.Communicator communicator)
@@ -45,16 +47,28 @@ public class PluginI implements com.zeroc.Ice.Plugin
             }
             properties.setProperty("IceDiscovery.Multicast.Endpoints", s.toString());
         }
-        if(properties.getProperty("IceDiscovery.Reply.Endpoints").isEmpty())
+
+        String lookupEndpoints = properties.getProperty("IceDiscovery.Lookup");
+        if(lookupEndpoints.isEmpty())
         {
-            StringBuilder s = new StringBuilder();
-            s.append("udp");
-            if(!intf.isEmpty())
+            int protocol = ipv4 && !preferIPv6 ? Network.EnableIPv4 : Network.EnableIPv6;
+            java.util.List<String> interfaces = Network.getInterfacesForMulticast(intf, protocol);
+            for(String p : interfaces)
             {
-                s.append(" -h \"").append(intf).append("\"");
+                if(p != interfaces.get(0))
+                {
+                    lookupEndpoints += ":";
+                }
+                lookupEndpoints += "udp -h \"" + address + "\" -p " + port + " --interface \"" + p + "\"";
             }
-            properties.setProperty("IceDiscovery.Reply.Endpoints", s.toString());
         }
+
+        if(properties.getProperty("IceDiscovery.Reply.Endpoints").isEmpty())
+        {
+            properties.setProperty("IceDiscovery.Reply.Endpoints",
+                                   "udp -h " + (intf.isEmpty() ? "*" : "\"" + intf + "\""));
+        }
+
         if(properties.getProperty("IceDiscovery.Locator.Endpoints").isEmpty())
         {
             properties.setProperty("IceDiscovery.Locator.AdapterId", java.util.UUID.randomUUID().toString());
@@ -71,34 +85,8 @@ public class PluginI implements com.zeroc.Ice.Plugin
         com.zeroc.Ice.LocatorRegistryPrx locatorRegistryPrx = com.zeroc.Ice.LocatorRegistryPrx.uncheckedCast(
             _locatorAdapter.addWithUUID(locatorRegistry));
 
-        String lookupEndpoints = properties.getProperty("IceDiscovery.Lookup");
-        if(lookupEndpoints.isEmpty())
-        {
-            StringBuilder s = new StringBuilder();
-            s.append("udp -h \"").append(address).append("\" -p ").append(port);
-            if(!intf.isEmpty())
-            {
-                s.append(" --interface \"").append(intf).append("\"");
-            }
-            lookupEndpoints = s.toString();
-        }
-
         com.zeroc.Ice.ObjectPrx lookupPrx = _communicator.stringToProxy("IceDiscovery/Lookup -d:" + lookupEndpoints);
         lookupPrx = lookupPrx.ice_collocationOptimized(false); // No collocation optimization for the multicast proxy!
-        try
-        {
-            lookupPrx.ice_getConnection();
-        }
-        catch(com.zeroc.Ice.LocalException ex)
-        {
-            StringBuilder b = new StringBuilder();
-            b.append("IceDiscovery is unable to establish a multicast connection:\n");
-            b.append("proxy = ");
-            b.append(lookupPrx.toString());
-            b.append('\n');
-            b.append(ex.toString());
-            throw new com.zeroc.Ice.PluginInitializationException(b.toString());
-        }
 
         //
         // Add lookup and lookup reply Ice objects
diff --git a/java/src/IceGridGUI/src/main/java/com/zeroc/IceGridGUI/SessionKeeper.java b/java/src/IceGridGUI/src/main/java/com/zeroc/IceGridGUI/SessionKeeper.java
index a12122ea4cf..9aeb8315872 100644
--- a/java/src/IceGridGUI/src/main/java/com/zeroc/IceGridGUI/SessionKeeper.java
+++ b/java/src/IceGridGUI/src/main/java/com/zeroc/IceGridGUI/SessionKeeper.java
@@ -62,9 +62,8 @@ import javax.naming.ldap.Rdn;
 import java.net.NetworkInterface;
 import java.net.InetAddress;
 
-import com.zeroc.IceLocatorDiscovery.LookupPrx;
-import com.zeroc.IceLocatorDiscovery.LookupReplyPrx;
-import com.zeroc.IceLocatorDiscovery.LookupReply;
+import com.zeroc.IceLocatorDiscovery.Plugin;
+import com.zeroc.IceLocatorDiscovery.PluginFactory;
 
 import com.zeroc.IceGrid.*;
 
@@ -1075,175 +1074,67 @@ public class SessionKeeper
             _nextButton.requestFocusInWindow();
         }
 
-        public void destroyDiscoveryAdapter()
-        {
-            synchronized(SessionKeeper.this)
-            {
-                if(_discoveryAdapter != null)
-                {
-                    SwingUtilities.invokeLater(() ->
-                        {
-                            if(_directDiscoveryEndpointModel.size() > 0)
-                            {
-                                _discoveryStatus.setText("");
-                            }
-                            else
-                            {
-                                _discoveryStatus.setText("No registries found");
-                            }
-                        });
-                    _discoveryAdapter.destroy();
-                    _discoveryAdapter = null;
-                }
-            }
-        }
-
-        public void refreshDiscoveryEndpoints()
+        public void refreshDiscoveryLocators()
         {
             final com.zeroc.Ice.Communicator communicator = _coordinator.getCommunicator();
-            if(_discoveryLookupReply == null)
-            {
-                _discoveryLookupReply = new LookupReply()
-                    {
-                        @Override
-                        public void foundLocator(final com.zeroc.Ice.LocatorPrx locator, com.zeroc.Ice.Current curr)
-                        {
-                            SwingUtilities.invokeLater(() ->
-                                {
-                                    if(_directDiscoveryEndpointModel.indexOf(locator) == -1)
-                                    {
-                                        _directDiscoveryEndpointModel.addElement(locator);
-                                    }
-
-                                    if(_directDiscoveryEndpointModel.size() > 0 &&
-                                        _directDiscoveryEndpointList.getSelectedIndex() == -1)
-                                    {
-                                        _directDiscoveryEndpointList.setSelectedIndex(0);
-                                    }
-                                });
-                        }
-                    };
-            }
-
             _discoveryStatus.setText("Searching for registries...");
-
-            //
-            // If there isn't any search in progress clear the endpoint list.
-            //
-            synchronized(SessionKeeper.this)
-            {
-                if(_discoveryAdapter == null)
-                {
-                    _directDiscoveryEndpointModel.clear();
-                }
-            }
-
-            final com.zeroc.Ice.Properties properties = communicator.getProperties();
-            final String intf = _discoveryInterfaces.getSelectedItem().toString();
-
-            String lookupEndpoints = properties.getProperty("IceGridAdmin.Discovery.Lookup");
-            String address;
-            if(properties.getPropertyAsIntWithDefault("Ice.IPv4", 1) > 0 &&
-               properties.getPropertyAsInt("Ice.PreferIPv6Address") <= 0)
-            {
-                address = "239.255.0.1";
-            }
-            else
-            {
-                address = "ff15::1";
-            }
-            if(lookupEndpoints.isEmpty())
-            {
-                StringBuilder s = new StringBuilder();
-                s.append("udp -h \"");
-                s.append(properties.getPropertyWithDefault("IceGridAdmin.Discovery.Address", address));
-                s.append("\" -p ");
-                s.append(4061);
-                if(!intf.isEmpty())
-                {
-                    s.append(" --interface \"").append(intf).append("\"");
-                }
-                lookupEndpoints = s.toString();
-            }
-
             try
             {
-                final LookupPrx lookupPrx = LookupPrx.uncheckedCast(
-                    communicator.stringToProxy("IceLocatorDiscovery/Lookup -d:" +
-                                               lookupEndpoints).ice_collocationOptimized(false).ice_router(null));
-
                 new Thread(() ->
                     {
                         synchronized(SessionKeeper.this)
                         {
-                            //
-                            // If search is in progress when refresh is hit, cancel the
-                            // finish task we will schedule a new one with this new
-                            // search.
-                            //
-                            if(_discoveryFinishTask != null)
-                            {
-                                _discoveryFinishTask.cancel();
-                            }
-
-                            if(properties.getProperty("IceGridAdmin.Discovery.Reply.Endpoints").isEmpty())
+                            try
                             {
-                                StringBuilder s = new StringBuilder();
-                                s.append("udp");
-                                if(!intf.isEmpty())
+                                if(_discoveryPlugin == null)
                                 {
-                                    s.append(" -h \"").append(intf).append("\"");
+                                    PluginFactory f = new PluginFactory();
+                                    _discoveryPlugin = (Plugin)f.create(communicator, "IceGridAdmin.Discovery", null);
+                                    _discoveryPlugin.initialize();
                                 }
-                                properties.setProperty("IceGridAdmin.Discovery.Reply.Endpoints", s.toString());
-                            }
 
-                            try
-                            {
-                                if(_discoveryAdapter == null)
+                                final List<com.zeroc.Ice.LocatorPrx> locators = _discoveryPlugin.getLocators("", 1000);
+                                SwingUtilities.invokeLater(() ->
                                 {
-                                    _discoveryAdapter = communicator.createObjectAdapter(
-                                        "IceGridAdmin.Discovery.Reply");
-                                    _discoveryAdapter.activate();
-                                    _discoveryReplyPrx = LookupReplyPrx.uncheckedCast(
-                                        _discoveryAdapter.addWithUUID(_discoveryLookupReply).ice_datagram());
-                                }
+                                    _directDiscoveryLocatorModel.clear();
+                                    for(com.zeroc.Ice.LocatorPrx locator : locators)
+                                    {
+                                        _directDiscoveryLocatorModel.addElement(locator);
+                                    }
+                                    if(_directDiscoveryLocatorModel.size() > 0 &&
+                                       _directDiscoveryLocatorList.getSelectedIndex() == -1)
+                                    {
+                                        _directDiscoveryLocatorList.setSelectedIndex(0);
+                                    }
 
-                                lookupPrx.findLocator("", _discoveryReplyPrx);
+                                    if(_directDiscoveryLocatorModel.size() > 0)
+                                    {
+                                        _discoveryStatus.setText("");
+                                    }
+                                    else
+                                    {
+                                        _discoveryStatus.setText("No registries found");
+                                    }
+                                });
                             }
                             catch(final com.zeroc.Ice.LocalException ex)
                             {
-                                ex.printStackTrace();
-                                destroyDiscoveryAdapter();
                                 SwingUtilities.invokeLater(() ->
                                     {
+                                        _discoveryStatus.setText("No registries found");
                                         JOptionPane.showMessageDialog(ConnectionWizardDialog.this,
                                                                       ex.toString(),
-                                                                      "Error while looking up locator endpoints",
+                                                                      "Error while looking up registries",
                                                                       JOptionPane.ERROR_MESSAGE);
                                     });
                             }
-
-                            //
-                            // We schedule a timer task to destroy the discovery adapter after 2
-                            // seconds, the user doesn't need to wait, discovered proxies are
-                            // added as they are found.
-                            //
-                            _discoveryFinishTask = new java.util.TimerTask()
-                            {
-                                @Override
-                                public void run()
-                                {
-                                    destroyDiscoveryAdapter();
-                                }
-                            };
-                            new java.util.Timer().schedule(_discoveryFinishTask, 2000);
                         }
                     }).start();
             }
             catch(com.zeroc.Ice.LocalException ex)
             {
                 JOptionPane.showMessageDialog(ConnectionWizardDialog.this, ex.toString(),
-                                              "Error while looking up locator endpoints", JOptionPane.ERROR_MESSAGE);
+                                              "Error while looking up registries", JOptionPane.ERROR_MESSAGE);
             }
         }
 
@@ -1298,69 +1189,11 @@ public class SessionKeeper
                 builder.append(new JLabel("Connect to an IceGrid registry through a Glacier2 router."));
                 _cardPanel.add(builder.getPanel(), WizardStep.ConnectionTypeStep.toString());
             }
-            
-            JPanel discoveryInterface;
-            {
-                FormLayout layout = new FormLayout("pref, 2dlu, pref:grow", "pref");
-                DefaultFormBuilder builder = new DefaultFormBuilder(layout);
-                _discoveryInterfaces = new JComboBox();
-
-                builder.append("Discovery Interface:", _discoveryInterfaces);
-
-                List<String> addresses = new ArrayList<String>();
-                try
-                {
-                    Enumeration<NetworkInterface> p = NetworkInterface.getNetworkInterfaces();
-                    
-                    while(p != null && p.hasMoreElements())
-                    {
-                        NetworkInterface intf = p.nextElement();
-                        if(intf.isUp())
-                        {
-                            Enumeration<InetAddress> q = intf.getInetAddresses();
-                            while(q != null && q.hasMoreElements())
-                            {
-                                InetAddress address = q.nextElement();
-                                if(!address.isAnyLocalAddress())
-                                {
-                                    addresses.add(address.getHostAddress());
-                                }
-                            }
-                        }
-                    }
-                }
-                catch(java.net.SocketException ex)
-                {
-                    JOptionPane.showMessageDialog(ConnectionWizardDialog.this,
-                                                  ex.toString(),
-                                                  "Error retrieving network interfaces",
-                                                  JOptionPane.ERROR_MESSAGE);
-                }
-                
-                final com.zeroc.Ice.Properties properties = _coordinator.getCommunicator().getProperties();
-                String selected = properties.getPropertyWithDefault("IceGridAdmin.Discovery.Interface", "127.0.0.1");
-                if(!addresses.contains(selected))
-                {
-                    addresses.add(selected);
-                }
-
-                _discoveryInterfaces.setModel(new DefaultComboBoxModel(addresses.toArray()));
-                _discoveryInterfaces.setSelectedItem(selected);
-                _discoveryInterfaces.addActionListener(new ActionListener ()
-                    {
-                        @Override
-                        public void actionPerformed(ActionEvent e)
-                        {
-                            refreshDiscoveryEndpoints();
-                        }
-                    });
-                discoveryInterface = builder.getPanel();
-            }
 
-            // Direct Discovery Endpoint List
+            // Direct Discovery Locator List
             {
-                _directDiscoveryEndpointModel = new DefaultListModel<>();
-                _directDiscoveryEndpointList = new JList(_directDiscoveryEndpointModel)
+                _directDiscoveryLocatorModel = new DefaultListModel<>();
+                _directDiscoveryLocatorList = new JList(_directDiscoveryLocatorModel)
                     {
                         @Override
                         public String getToolTipText(MouseEvent evt)
@@ -1378,9 +1211,9 @@ public class SessionKeeper
                             return null;
                         }
                     };
-                _directDiscoveryEndpointList.setVisibleRowCount(7);
-                _directDiscoveryEndpointList.setFixedCellWidth(500);
-                _directDiscoveryEndpointList.addMouseListener(
+                _directDiscoveryLocatorList.setVisibleRowCount(7);
+                _directDiscoveryLocatorList.setFixedCellWidth(500);
+                _directDiscoveryLocatorList.addMouseListener(
                     new MouseAdapter()
                         {
                             @Override
@@ -1388,8 +1221,8 @@ public class SessionKeeper
                             {
                                 if(e.getClickCount() == 2 && e.getButton() == MouseEvent.BUTTON1)
                                 {
-                                    Object obj = _directDiscoveryEndpointModel.getElementAt(
-                                                            _directDiscoveryEndpointList.locationToIndex(e.getPoint()));
+                                    Object obj = _directDiscoveryLocatorModel.getElementAt(
+                                                            _directDiscoveryLocatorList.locationToIndex(e.getPoint()));
                                     if(obj != null && obj instanceof com.zeroc.Ice.LocatorPrx)
                                     {
                                         _nextButton.doClick(0);
@@ -1397,9 +1230,9 @@ public class SessionKeeper
                                 }
                             }
                         });
-                
 
-                _directDiscoveryEndpointList.addListSelectionListener(new ListSelectionListener()
+
+                _directDiscoveryLocatorList.addListSelectionListener(new ListSelectionListener()
                 {
                     @Override
                     public void valueChanged(ListSelectionEvent event)
@@ -1409,20 +1242,20 @@ public class SessionKeeper
                 });
 
                 ButtonGroup group = new ButtonGroup();
-                _directDiscoveryDiscoveredEndpoint = new JRadioButton(new AbstractAction("Discovered Endpoints")
+                _directDiscoveryDiscoveredLocators = new JRadioButton(new AbstractAction("Discovered Registries")
                 {
                     @Override
                     public void actionPerformed(ActionEvent e)
                     {
-                        _directDiscoveryEndpointList.setEnabled(true);
+                        _directDiscoveryLocatorList.setEnabled(true);
                         _discoveryStatus.setEnabled(true);
                         _discoveryRefresh.setEnabled(true);
                         validatePanel();
-                        refreshDiscoveryEndpoints();
+                        refreshDiscoveryLocators();
                     }
                 });
-                _directDiscoveryDiscoveredEndpoint.setSelected(true);
-                group.add(_directDiscoveryDiscoveredEndpoint);
+                _directDiscoveryDiscoveredLocators.setSelected(true);
+                group.add(_directDiscoveryDiscoveredLocators);
 
                 JPanel discoveryStatus;
                 {
@@ -1435,7 +1268,7 @@ public class SessionKeeper
                         @Override
                         public void actionPerformed(ActionEvent e)
                         {
-                            refreshDiscoveryEndpoints();
+                            refreshDiscoveryLocators();
                         }
                     });
 
@@ -1449,8 +1282,7 @@ public class SessionKeeper
                     @Override
                     public void actionPerformed(ActionEvent e)
                     {
-                        destroyDiscoveryAdapter();
-                        _directDiscoveryEndpointList.setEnabled(false);
+                        _directDiscoveryLocatorList.setEnabled(false);
                         _discoveryStatus.setEnabled(false);
                         _discoveryRefresh.setEnabled(false);
                         validatePanel();
@@ -1463,9 +1295,8 @@ public class SessionKeeper
                     DefaultFormBuilder builder = new DefaultFormBuilder(layout);
                     builder.border(Borders.DIALOG);
                     builder.rowGroupingEnabled(false);
-                    builder.append(_directDiscoveryDiscoveredEndpoint);
-                    builder.append(discoveryInterface);
-                    builder.append(createStrippedScrollPane(_directDiscoveryEndpointList));
+                    builder.append(_directDiscoveryDiscoveredLocators);
+                    builder.append(createStrippedScrollPane(_directDiscoveryLocatorList));
                     builder.append(discoveryStatus);
                     builder.append(_directDiscoveryManualEndpoint);
                     _cardPanel.add(builder.getPanel(), WizardStep.DirectDiscoveryChooseStep.toString());
@@ -2170,9 +2001,9 @@ public class SessionKeeper
                             {
                                 _cardLayout.show(_cardPanel, WizardStep.DirectDiscoveryChooseStep.toString());
                                 _wizardSteps.push(WizardStep.DirectDiscoveryChooseStep);
-                                if(_directDiscoveryDiscoveredEndpoint.isSelected())
+                                if(_directDiscoveryDiscoveredLocators.isSelected())
                                 {
-                                    refreshDiscoveryEndpoints();
+                                    refreshDiscoveryLocators();
                                 }
                                 break;
                             }
@@ -2186,9 +2017,9 @@ public class SessionKeeper
                                 }
                                 else
                                 {
-                                    com.zeroc.Ice.LocatorPrx locator = _directDiscoveryEndpointList.getSelectedValue();
+                                    com.zeroc.Ice.LocatorPrx locator = _directDiscoveryLocatorList.getSelectedValue();
                                     _directInstanceName.setText(locator.ice_getIdentity().category);
-                                    
+
                                     String endpoints = null;
                                     for(com.zeroc.Ice.Endpoint endpoint : locator.ice_getEndpoints())
                                     {
@@ -2496,7 +2327,8 @@ public class SessionKeeper
                     @Override
                     public void actionPerformed(ActionEvent e)
                     {
-                        destroyDiscoveryAdapter();
+                        _discoveryPlugin.destroy();
+                        _discoveryPlugin = null;
 
                         ConnectionInfo inf = getConfiguration();
                         if(inf == null)
@@ -2670,7 +2502,8 @@ public class SessionKeeper
                     @Override
                     public void actionPerformed(ActionEvent e)
                     {
-                        destroyDiscoveryAdapter();
+                        _discoveryPlugin.destroy();
+                        _discoveryPlugin = null;
                         dispose();
                     }
                 };
@@ -2707,7 +2540,7 @@ public class SessionKeeper
                     }
                     else
                     {
-                        _directDiscoveryEndpointList.requestFocusInWindow();
+                        _directDiscoveryLocatorList.requestFocusInWindow();
                     }
                     break;
                 }
@@ -2851,7 +2684,7 @@ public class SessionKeeper
                     }
                     else
                     {
-                        validated = _directDiscoveryEndpointList.getSelectedValue() != null;
+                        validated = _directDiscoveryLocatorList.getSelectedValue() != null;
                     }
                     break;
                 }
@@ -3247,17 +3080,13 @@ public class SessionKeeper
         private JCheckBox _directConnectToMaster;
 
         // Direct Discovery Endpoints
-        private JComboBox _discoveryInterfaces;
-        private JList<com.zeroc.Ice.LocatorPrx> _directDiscoveryEndpointList;
-        private DefaultListModel<com.zeroc.Ice.LocatorPrx> _directDiscoveryEndpointModel;
-        private JRadioButton _directDiscoveryDiscoveredEndpoint;
+        private JList<com.zeroc.Ice.LocatorPrx> _directDiscoveryLocatorList;
+        private DefaultListModel<com.zeroc.Ice.LocatorPrx> _directDiscoveryLocatorModel;
+        private JRadioButton _directDiscoveryDiscoveredLocators;
         private JLabel _discoveryStatus;
         private JButton _discoveryRefresh;
 
-        private java.util.TimerTask _discoveryFinishTask;
-        private com.zeroc.Ice.ObjectAdapter _discoveryAdapter;
-        private LookupReplyPrx _discoveryReplyPrx;
-        private LookupReply _discoveryLookupReply;
+        private Plugin _discoveryPlugin;
         private JRadioButton _directDiscoveryManualEndpoint;
 
         // Direct Endpoints panel components
diff --git a/java/src/IceLocatorDiscovery/src/main/java/com/zeroc/IceLocatorDiscovery/Plugin.java b/java/src/IceLocatorDiscovery/src/main/java/com/zeroc/IceLocatorDiscovery/Plugin.java
new file mode 100644
index 00000000000..b050046aab7
--- /dev/null
+++ b/java/src/IceLocatorDiscovery/src/main/java/com/zeroc/IceLocatorDiscovery/Plugin.java
@@ -0,0 +1,17 @@
+// **********************************************************************
+//
+// Copyright (c) 2003-2017 ZeroC, Inc. All rights reserved.
+//
+// This copy of Ice is licensed to you under the terms described in the
+// ICE_LICENSE file included in this distribution.
+//
+// **********************************************************************
+
+package com.zeroc.IceLocatorDiscovery;
+
+import java.util.List;
+
+public interface Plugin extends com.zeroc.Ice.Plugin
+{
+    List<com.zeroc.Ice.LocatorPrx> getLocators(String instanceName, int waitTime);
+}
diff --git a/java/src/IceLocatorDiscovery/src/main/java/com/zeroc/IceLocatorDiscovery/PluginFactory.java b/java/src/IceLocatorDiscovery/src/main/java/com/zeroc/IceLocatorDiscovery/PluginFactory.java
index 6c6b82f4fac..cec8ddf78b3 100644
--- a/java/src/IceLocatorDiscovery/src/main/java/com/zeroc/IceLocatorDiscovery/PluginFactory.java
+++ b/java/src/IceLocatorDiscovery/src/main/java/com/zeroc/IceLocatorDiscovery/PluginFactory.java
@@ -14,6 +14,6 @@ public class PluginFactory implements com.zeroc.Ice.PluginFactory
     @Override
     public com.zeroc.Ice.Plugin create(com.zeroc.Ice.Communicator communicator, String name, String[] args)
     {
-        return new PluginI(communicator);
+        return new PluginI(name, communicator);
     }
 }
diff --git a/java/src/IceLocatorDiscovery/src/main/java/com/zeroc/IceLocatorDiscovery/PluginI.java b/java/src/IceLocatorDiscovery/src/main/java/com/zeroc/IceLocatorDiscovery/PluginI.java
index 5cdf0d781ff..3a50fd6c79b 100644
--- a/java/src/IceLocatorDiscovery/src/main/java/com/zeroc/IceLocatorDiscovery/PluginI.java
+++ b/java/src/IceLocatorDiscovery/src/main/java/com/zeroc/IceLocatorDiscovery/PluginI.java
@@ -9,13 +9,16 @@
 
 package com.zeroc.IceLocatorDiscovery;
 
+import com.zeroc.IceInternal.Network;
 import java.util.List;
 import java.util.Arrays;
 import java.util.ArrayList;
+import java.util.Map;
+import java.util.HashMap;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionStage;
 
-class PluginI implements com.zeroc.Ice.Plugin
+class PluginI implements Plugin
 {
     private static class Request
     {
@@ -135,24 +138,85 @@ class PluginI implements com.zeroc.Ice.Plugin
 
     private static class LocatorI implements com.zeroc.Ice.BlobjectAsync
     {
-        LocatorI(LookupPrx lookup, com.zeroc.Ice.Properties properties, String instanceName,
+        LocatorI(String name, LookupPrx lookup, com.zeroc.Ice.Properties properties, String instanceName,
                  com.zeroc.Ice.LocatorPrx voidLocator)
         {
-            _lookup = lookup;
-            _timeout = properties.getPropertyAsIntWithDefault("IceLocatorDiscovery.Timeout", 300);
-            _retryCount = properties.getPropertyAsIntWithDefault("IceLocatorDiscovery.RetryCount", 3);
-            _retryDelay = properties.getPropertyAsIntWithDefault("IceLocatorDiscovery.RetryDelay", 2000);
+            _timeout = properties.getPropertyAsIntWithDefault(name + ".Timeout", 300);
+            _retryCount = properties.getPropertyAsIntWithDefault(name + ".RetryCount", 3);
+            _retryDelay = properties.getPropertyAsIntWithDefault(name + ".RetryDelay", 2000);
             _timer = com.zeroc.IceInternal.Util.getInstance(lookup.ice_getCommunicator()).timer();
             _instanceName = instanceName;
             _warned = false;
             _locator = lookup.ice_getCommunicator().getDefaultLocator();
             _voidLocator = voidLocator;
             _pendingRetryCount = 0;
+
+            try
+            {
+                lookup.ice_getConnection();
+            }
+            catch(com.zeroc.Ice.LocalException ex)
+            {
+                StringBuilder b = new StringBuilder();
+                b.append("IceDiscovery is unable to establish a multicast connection:\n");
+                b.append("proxy = ");
+                b.append(lookup.toString());
+                b.append('\n');
+                b.append(ex.toString());
+                throw new com.zeroc.Ice.PluginInitializationException(b.toString());
+            }
+
+            //
+            // Create one lookup proxy per endpoint from the given proxy. We want to send a multicast
+            // datagram on each endpoint.
+            //
+            com.zeroc.Ice.Endpoint[] single = new com.zeroc.Ice.Endpoint[1];
+            for(com.zeroc.Ice.Endpoint endpt : lookup.ice_getEndpoints())
+            {
+                try
+                {
+                    single[0] = endpt;
+                    LookupPrx l = (LookupPrx)lookup.ice_endpoints(single);
+                    l.ice_getConnection();
+                    _lookup.put(l, null);
+                }
+                catch(com.zeroc.Ice.LocalException ex)
+                {
+                }
+            }
+            assert(!_lookup.isEmpty());
         }
 
         public void setLookupReply(LookupReplyPrx lookupReply)
         {
-            _lookupReply = lookupReply;
+            //
+            // Use a lookup reply proxy whose adress matches the interface used to send multicast datagrams.
+            //
+            com.zeroc.Ice.Endpoint[] single = new com.zeroc.Ice.Endpoint[1];
+            for(Map.Entry<LookupPrx, LookupReplyPrx> entry : _lookup.entrySet())
+            {
+                com.zeroc.Ice.UDPEndpointInfo info =
+                    (com.zeroc.Ice.UDPEndpointInfo)entry.getKey().ice_getEndpoints()[0].getInfo();
+                if(!info.mcastInterface.isEmpty())
+                {
+                    for(com.zeroc.Ice.Endpoint q : lookupReply.ice_getEndpoints())
+                    {
+                        com.zeroc.Ice.EndpointInfo r = q.getInfo();
+                        if(r instanceof com.zeroc.Ice.IPEndpointInfo &&
+                           ((com.zeroc.Ice.IPEndpointInfo)r).host.equals(info.mcastInterface))
+                        {
+                            single[0] = q;
+                            entry.setValue((LookupReplyPrx)lookupReply.ice_endpoints(single));
+                        }
+                    }
+                }
+
+                if(entry.getValue() == null)
+                {
+                    // Fallback: just use the given lookup reply proxy if no matching endpoint found.
+                    entry.setValue(lookupReply);
+                }
+            }
         }
 
         @Override
@@ -164,6 +228,56 @@ class PluginI implements com.zeroc.Ice.Plugin
             return f;
         }
 
+        public List<com.zeroc.Ice.LocatorPrx>
+        getLocators(String instanceName, int waitTime)
+        {
+            //
+            // Clear locators from previous search.
+            //
+            synchronized(this)
+            {
+                _locators.clear();
+            }
+
+            //
+            // Find a locator
+            //
+            invoke(null, null);
+
+            //
+            // Wait for responses
+            //
+            try
+            {
+                if(instanceName.isEmpty())
+                {
+                    Thread.sleep(waitTime);
+                }
+                else
+                {
+                    synchronized(this)
+                    {
+                        while(!_locators.containsKey(instanceName) && _pendingRetryCount > 0)
+                        {
+                            wait(waitTime);
+                        }
+                    }
+                }
+            }
+            catch(java.lang.InterruptedException ex)
+            {
+                throw new com.zeroc.Ice.OperationInterruptedException();
+            }
+
+            //
+            // Return found locators
+            //
+            synchronized(this)
+            {
+                return new ArrayList<>(_locators.values());
+            }
+        }
+
         public synchronized void foundLocator(com.zeroc.Ice.LocatorPrx locator)
         {
             if(locator == null ||
@@ -176,7 +290,8 @@ class PluginI implements com.zeroc.Ice.Plugin
             // If we already have a locator assigned, ensure the given locator
             // has the same identity, otherwise ignore it.
             //
-            if(_locator != null && !locator.ice_getIdentity().category.equals(_locator.ice_getIdentity().category))
+            if(!_pendingRequests.isEmpty() &&
+               _locator != null && !locator.ice_getIdentity().category.equals(_locator.ice_getIdentity().category))
             {
                 if(!_warned)
                 {
@@ -201,14 +316,15 @@ class PluginI implements com.zeroc.Ice.Plugin
                 _pendingRetryCount = 0;
             }
 
-            if(_locator != null)
+            com.zeroc.Ice.LocatorPrx l =
+                _pendingRequests.isEmpty() ? _locators.get(locator.ice_getIdentity().category) : _locator;
+            if(l != null)
             {
                 //
                 // We found another locator replica, append its endpoints to the
                 // current locator proxy endpoints.
                 //
-                List<com.zeroc.Ice.Endpoint> newEndpoints = new ArrayList<>(
-                    Arrays.asList(_locator.ice_getEndpoints()));
+                List<com.zeroc.Ice.Endpoint> newEndpoints = new ArrayList<>(Arrays.asList(l.ice_getEndpoints()));
                 for(com.zeroc.Ice.Endpoint p : locator.ice_getEndpoints())
                 {
                     //
@@ -229,50 +345,72 @@ class PluginI implements com.zeroc.Ice.Plugin
                     }
 
                 }
-                _locator = (com.zeroc.Ice.LocatorPrx)_locator.ice_endpoints(
+                l = (com.zeroc.Ice.LocatorPrx)l.ice_endpoints(
                     newEndpoints.toArray(new com.zeroc.Ice.Endpoint[newEndpoints.size()]));
             }
             else
             {
-                _locator = locator;
+                l = locator;
+            }
+
+            if(_pendingRequests.isEmpty())
+            {
+                _locators.put(locator.ice_getIdentity().category, l);
+                notify();
+            }
+            else
+            {
+                _locator = l;
                 if(_instanceName.isEmpty())
                 {
                     _instanceName = _locator.ice_getIdentity().category; // Stick to the first locator
                 }
-            }
 
-            //
-            // Send pending requests if any.
-            //
-            for(Request req : _pendingRequests)
-            {
-                req.invoke(_locator);
+                //
+                // Send pending requests if any.
+                //
+                for(Request req : _pendingRequests)
+                {
+                    req.invoke(_locator);
+                }
+                _pendingRequests.clear();
             }
-            _pendingRequests.clear();
         }
 
         public synchronized void invoke(com.zeroc.Ice.LocatorPrx locator, Request request)
         {
             if(_locator != null && _locator != locator)
             {
-                request.invoke(_locator);
+                if(request != null)
+                {
+                    request.invoke(_locator);
+                }
             }
             else if(com.zeroc.IceInternal.Time.currentMonotonicTimeMillis() < _nextRetry)
             {
-                request.invoke(_voidLocator); // Don't retry to find a locator before the retry delay expires
+                if(request != null)
+                {
+                    request.invoke(_voidLocator); // Don't retry to find a locator before the retry delay expires
+                }
             }
             else
             {
                 _locator = null;
 
-                _pendingRequests.add(request);
+                if(request != null)
+                {
+                    _pendingRequests.add(request);
+                }
 
                 if(_pendingRetryCount == 0) // No request in progress
                 {
                     _pendingRetryCount = _retryCount;
                     try
                     {
-                        _lookup.findLocatorAsync(_instanceName, _lookupReply); // Send multicast request.
+                        for(Map.Entry<LookupPrx, LookupReplyPrx> entry : _lookup.entrySet())
+                        {
+                            entry.getKey().findLocatorAsync(_instanceName, entry.getValue()); // Send multicast request.
+                        }
                         _future = _timer.schedule(_retryTask, _timeout, java.util.concurrent.TimeUnit.MILLISECONDS);
                     }
                     catch(com.zeroc.Ice.LocalException ex)
@@ -299,7 +437,10 @@ class PluginI implements com.zeroc.Ice.Plugin
                     {
                         try
                         {
-                            _lookup.findLocatorAsync(_instanceName, _lookupReply); // Send multicast request.
+                            for(Map.Entry<LookupPrx, LookupReplyPrx> entry : _lookup.entrySet())
+                            {
+                                entry.getKey().findLocatorAsync(_instanceName, entry.getValue()); // Send multicast request
+                            }
                             _future = _timer.schedule(_retryTask, _timeout, java.util.concurrent.TimeUnit.MILLISECONDS);
                             return;
                         }
@@ -320,7 +461,7 @@ class PluginI implements com.zeroc.Ice.Plugin
             }
         };
 
-        private final LookupPrx _lookup;
+        private final Map<LookupPrx, LookupReplyPrx> _lookup = new java.util.HashMap<>();
         private final int _timeout;
         private java.util.concurrent.Future<?> _future;
         private final java.util.concurrent.ScheduledExecutorService _timer;
@@ -329,9 +470,9 @@ class PluginI implements com.zeroc.Ice.Plugin
 
         private String _instanceName;
         private boolean _warned;
-        private LookupReplyPrx _lookupReply;
         private com.zeroc.Ice.LocatorPrx _locator;
         private com.zeroc.Ice.LocatorPrx _voidLocator;
+        private Map<String, com.zeroc.Ice.LocatorPrx> _locators = new HashMap<>();
 
         private int _pendingRetryCount;
         private List<Request> _pendingRequests = new ArrayList<>();
@@ -354,8 +495,9 @@ class PluginI implements com.zeroc.Ice.Plugin
         private final LocatorI _locator;
     }
 
-    public PluginI(com.zeroc.Ice.Communicator communicator)
+    public PluginI(String name, com.zeroc.Ice.Communicator communicator)
     {
+        _name = name;
         _communicator = communicator;
     }
 
@@ -369,76 +511,63 @@ class PluginI implements com.zeroc.Ice.Plugin
         String address;
         if(ipv4 && !preferIPv6)
         {
-            address = properties.getPropertyWithDefault("IceLocatorDiscovery.Address", "239.255.0.1");
+            address = properties.getPropertyWithDefault(_name + ".Address", "239.255.0.1");
         }
         else
         {
-            address = properties.getPropertyWithDefault("IceLocatorDiscovery.Address", "ff15::1");
+            address = properties.getPropertyWithDefault(_name + ".Address", "ff15::1");
         }
-        int port = properties.getPropertyAsIntWithDefault("IceLocatorDiscovery.Port", 4061);
-        String intf = properties.getProperty("IceLocatorDiscovery.Interface");
+        int port = properties.getPropertyAsIntWithDefault(_name + ".Port", 4061);
+        String intf = properties.getProperty(_name + ".Interface");
 
-        if(properties.getProperty("IceLocatorDiscovery.Reply.Endpoints").isEmpty())
+        String lookupEndpoints = properties.getProperty(_name + ".Lookup");
+        if(lookupEndpoints.isEmpty())
         {
-            StringBuilder s = new StringBuilder();
-            s.append("udp");
-            if(!intf.isEmpty())
+            int protocol = ipv4 && !preferIPv6 ? Network.EnableIPv4 : Network.EnableIPv6;
+            java.util.List<String> interfaces = Network.getInterfacesForMulticast(intf, protocol);
+            for(String p : interfaces)
             {
-                s.append(" -h \"").append(intf).append("\"");
+                if(p != interfaces.get(0))
+                {
+                    lookupEndpoints += ":";
+                }
+                lookupEndpoints += "udp -h \"" + address + "\" -p " + port + " --interface \"" + p + "\"";
             }
-            properties.setProperty("IceLocatorDiscovery.Reply.Endpoints", s.toString());
         }
-        if(properties.getProperty("IceLocatorDiscovery.Locator.Endpoints").isEmpty())
+
+        if(properties.getProperty(_name + ".Reply.Endpoints").isEmpty())
+        {
+            properties.setProperty(_name + ".Reply.Endpoints", "udp -h " + (intf.isEmpty() ? "*" : "\"" + intf + "\""));
+        }
+
+        if(properties.getProperty(_name + ".Locator.Endpoints").isEmpty())
         {
-            properties.setProperty("IceLocatorDiscovery.Locator.AdapterId", java.util.UUID.randomUUID().toString());
+            properties.setProperty(_name + ".Locator.AdapterId", java.util.UUID.randomUUID().toString());
         }
 
-        _replyAdapter = _communicator.createObjectAdapter("IceLocatorDiscovery.Reply");
-        _locatorAdapter = _communicator.createObjectAdapter("IceLocatorDiscovery.Locator");
+        _replyAdapter = _communicator.createObjectAdapter(_name + ".Reply");
+        _locatorAdapter = _communicator.createObjectAdapter(_name + ".Locator");
 
         // We don't want those adapters to be registered with the locator so clear their locator.
         _replyAdapter.setLocator(null);
         _locatorAdapter.setLocator(null);
 
-        String lookupEndpoints = properties.getProperty("IceLocatorDiscovery.Lookup");
-        if(lookupEndpoints.isEmpty())
-        {
-            StringBuilder s = new StringBuilder();
-            s.append("udp -h \"").append(address).append("\" -p ").append(port);
-            if(!intf.isEmpty())
-            {
-                s.append(" --interface \"").append(intf).append("\"");
-            }
-            lookupEndpoints = s.toString();
-        }
-
         com.zeroc.Ice.ObjectPrx lookupPrx =
             _communicator.stringToProxy("IceLocatorDiscovery/Lookup -d:" + lookupEndpoints);
         lookupPrx = lookupPrx.ice_collocationOptimized(false); // No collocation optimization for the multicast proxy!
-        try
-        {
-            lookupPrx.ice_getConnection(); // Ensure we can establish a connection to the multicast proxy
-        }
-        catch(com.zeroc.Ice.LocalException ex)
-        {
-            StringBuilder s = new StringBuilder();
-            s.append("IceLocatorDiscovery is unable to establish a multicast connection:\n");
-            s.append("proxy = ").append(lookupPrx.toString()).append("\n").append(ex);
-            throw new com.zeroc.Ice.PluginInitializationException(s.toString());
-        }
 
         com.zeroc.Ice.LocatorPrx voidLoc =
             com.zeroc.Ice.LocatorPrx.uncheckedCast(_locatorAdapter.addWithUUID(new VoidLocatorI()));
 
-        String instanceName = properties.getProperty("IceLocatorDiscovery.InstanceName");
+        String instanceName = properties.getProperty(_name + ".InstanceName");
         com.zeroc.Ice.Identity id = new com.zeroc.Ice.Identity();
         id.name = "Locator";
         id.category = !instanceName.isEmpty() ? instanceName : java.util.UUID.randomUUID().toString();
-        LocatorI locator = new LocatorI(LookupPrx.uncheckedCast(lookupPrx), properties, instanceName, voidLoc);
-        _communicator.setDefaultLocator(com.zeroc.Ice.LocatorPrx.uncheckedCast(_locatorAdapter.addWithUUID(locator)));
+        _locator = new LocatorI(_name, LookupPrx.uncheckedCast(lookupPrx), properties, instanceName, voidLoc);
+        _communicator.setDefaultLocator(com.zeroc.Ice.LocatorPrx.uncheckedCast(_locatorAdapter.addWithUUID(_locator)));
 
-        com.zeroc.Ice.ObjectPrx lookupReply = _replyAdapter.addWithUUID(new LookupReplyI(locator)).ice_datagram();
-        locator.setLookupReply(LookupReplyPrx.uncheckedCast(lookupReply));
+        com.zeroc.Ice.ObjectPrx lookupReply = _replyAdapter.addWithUUID(new LookupReplyI(_locator)).ice_datagram();
+        _locator.setLookupReply(LookupReplyPrx.uncheckedCast(lookupReply));
 
         _replyAdapter.activate();
         _locatorAdapter.activate();
@@ -451,7 +580,15 @@ class PluginI implements com.zeroc.Ice.Plugin
         _locatorAdapter.destroy();
     }
 
+    public List<com.zeroc.Ice.LocatorPrx>
+    getLocators(String instanceName, int waitTime)
+    {
+        return _locator.getLocators(instanceName, waitTime);
+    }
+
+    private String _name;
     private com.zeroc.Ice.Communicator _communicator;
     private com.zeroc.Ice.ObjectAdapter _locatorAdapter;
     private com.zeroc.Ice.ObjectAdapter _replyAdapter;
+    private LocatorI _locator;
 }