diff --git a/Implab.Playground/Implab.Playground.csproj b/Implab.Playground/Implab.Playground.csproj
--- a/Implab.Playground/Implab.Playground.csproj
+++ b/Implab.Playground/Implab.Playground.csproj
@@ -19,7 +19,9 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Unity" Version="5.8.5" />
+    <PackageReference Include="Unity" Version="5.8.6" />
+    <PackageReference Include="System.Reactive" Version="4.0.0" />
+    
   </ItemGroup>
  
 </Project>
diff --git a/Implab.Playground/Program.cs b/Implab.Playground/Program.cs
--- a/Implab.Playground/Program.cs
+++ b/Implab.Playground/Program.cs
@@ -12,6 +12,7 @@ using Unity.Injection;
 using Unity.Registration;
 
 namespace Implab.Playground {
+    using System.Reactive.Linq;
     using static Trace<Bar>;
     
     class Foo {
@@ -27,14 +28,10 @@ namespace Implab.Playground {
             Trace<Foo>.Log("First!");
             Log("+1!");
             
-            using(TraceRegistry.Global.Subscribe(x => {
-                var ch  = x as TraceSourceChannel;
-                if (ch == null)
-                    return;
-
+            using(TraceRegistry.Global.OfType<TraceSourceChannel>().Subscribe(ch => {
                 Console.WriteLine($"{ch.Id}: {ch.Source.Name}");
 
-            }, true)) {
+            })) {
                 Trace<Foo>.Log("Hi!");
                 Log("Respect!");
             }
diff --git a/Implab.ServiceHost/Implab.ServiceHost.csproj b/Implab.ServiceHost/Implab.ServiceHost.csproj
--- a/Implab.ServiceHost/Implab.ServiceHost.csproj
+++ b/Implab.ServiceHost/Implab.ServiceHost.csproj
@@ -17,7 +17,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Unity" Version="5.8.5" />
+    <PackageReference Include="Unity" Version="5.8.6" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/Implab.Test/DiagnosticsTest.cs b/Implab.Test/DiagnosticsTest.cs
--- a/Implab.Test/DiagnosticsTest.cs
+++ b/Implab.Test/DiagnosticsTest.cs
@@ -23,14 +23,7 @@ namespace Implab.Test {
             TraceRegistry.Global.Subscribe(x => {
                 visited++;
                 found = x as TraceSourceChannel;
-            }, false);
-
-            Assert.Equal(0, visited);
-
-            TraceRegistry.Global.Subscribe(x => {
-                visited++;
-                found = x as TraceSourceChannel;
-            }, true);
+            });
 
             Assert.Equal(1,visited);
             Assert.Equal(channel, found);
diff --git a/Implab.Test/Implab.Test.csproj b/Implab.Test/Implab.Test.csproj
--- a/Implab.Test/Implab.Test.csproj
+++ b/Implab.Test/Implab.Test.csproj
@@ -14,6 +14,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.6.0-preview-20180109-01" />
+    <PackageReference Include="System.Reactive" Version="4.0.0" />
     <PackageReference Include="xunit" Version="2.3.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
     <ProjectReference Include="../Implab/Implab.csproj"/>
diff --git a/Implab/Diagnostics/TraceRegistry.cs b/Implab/Diagnostics/TraceRegistry.cs
--- a/Implab/Diagnostics/TraceRegistry.cs
+++ b/Implab/Diagnostics/TraceRegistry.cs
@@ -4,11 +4,10 @@ using System.Diagnostics;
 using Implab.Parallels;
 
 namespace Implab.Diagnostics {
-    public class TraceRegistry {
+    public class TraceRegistry: IObservable<TraceChannel> {
 
         class Subscription : IDisposable {
             readonly WeakReference<TraceRegistry> m_registry;
-            readonly Action<object> m_unsubscribe;
 
             public Subscription(TraceRegistry registry) {
                 m_registry = new WeakReference<TraceRegistry>(registry);
@@ -21,28 +20,32 @@ namespace Implab.Diagnostics {
             }
         }
 
+        /// <summary>
+        /// The global collection of available diagnostic channels
+        /// </summary>
+        /// <returns></returns>
         public static TraceRegistry Global { get; } = new TraceRegistry();
 
         readonly object m_lock = new object();
 
-        readonly Dictionary<object, Action<TraceChannel>> m_subscriptions = new Dictionary<object, Action<TraceChannel>>();
+        readonly Dictionary<object, IObserver<TraceChannel>> m_subscriptions = new Dictionary<object, IObserver<TraceChannel>>();
         readonly SimpleAsyncQueue<TraceChannel> m_channels = new SimpleAsyncQueue<TraceChannel>();
 
-        internal void Register(TraceChannel channel) {
+        public void Register(TraceChannel channel) {
             // notifications can run in parallel
-            Action<TraceChannel>[] handlers = null;
+            IObserver<TraceChannel>[] handlers = null;
             
             lock(m_lock) {
                 m_channels.Enqueue(channel);
                 if (m_subscriptions.Count > 0) {
-                    handlers = new Action<TraceChannel>[m_subscriptions.Count];
+                    handlers = new IObserver<TraceChannel>[m_subscriptions.Count];
                     m_subscriptions.Values.CopyTo(handlers, 0);
                 }           
             }
 
             if (handlers != null)
                 foreach(var h in handlers)
-                    h(channel);
+                    h.OnNext(channel);
         }
 
         /// <summary>
@@ -51,7 +54,7 @@ namespace Implab.Diagnostics {
         /// </summary>
         /// <param name="handler"></param>
         /// <returns></returns>
-        public IDisposable Subscribe(Action<TraceChannel> handler, bool existing) {
+        public IDisposable Subscribe(IObserver<TraceChannel> handler) {
             Safe.ArgumentNotNull(handler, nameof(handler));
 
             var cookie = new Subscription(this);
@@ -66,9 +69,9 @@ namespace Implab.Diagnostics {
             }
 
             // announce previously declared channels if required
-            if (existing) {
+            if (snap != null) {
                 foreach(var c in snap)
-                    handler(c);
+                    handler.OnNext(c);
             }
 
             // return the subscription            
diff --git a/Implab/Implab.csproj b/Implab/Implab.csproj
--- a/Implab/Implab.csproj
+++ b/Implab/Implab.csproj
@@ -8,7 +8,7 @@
     and SharedLock, Trace helpers on top of System.Diagnostics, ObjectPool etc.
     </Description>
     <Copyright>2012-2018 Sergey Smirnov</Copyright>
-    <Version>3.0.12</Version>
+    <Version>3.0.14</Version>
     <PackageLicenseUrl>https://hg.implab.org/pub/ImplabNet/file/tip/Implab/license.txt</PackageLicenseUrl>
     <PackageProjectUrl>https://implab.org</PackageProjectUrl>
     <RepositoryUrl>https://hg.implab.org/pub/ImplabNet/</RepositoryUrl>