diff --git a/Implab.ServiceHost/Unity/DefaultParameterElement.cs b/Implab.ServiceHost/Unity/DefaultParameterElement.cs
--- a/Implab.ServiceHost/Unity/DefaultParameterElement.cs
+++ b/Implab.ServiceHost/Unity/DefaultParameterElement.cs
@@ -5,7 +5,7 @@ namespace Implab.ServiceHost.Unity
             get { return null; }
         }
 
-        internal override void Visit(InjectionValueBuilder builder) {
+        public override void Visit(InjectionValueBuilder builder) {
             builder.Visit(this);
         }
     }
diff --git a/Implab.ServiceHost/Unity/DependencyParameterElement.cs b/Implab.ServiceHost/Unity/DependencyParameterElement.cs
--- a/Implab.ServiceHost/Unity/DependencyParameterElement.cs
+++ b/Implab.ServiceHost/Unity/DependencyParameterElement.cs
@@ -9,7 +9,7 @@ namespace Implab.ServiceHost.Unity {
         [XmlAttribute("optional")]
         public bool Optional { get; set; }
 
-        internal override void Visit(InjectionValueBuilder builder) {
+        public override  void Visit(InjectionValueBuilder builder) {
             builder.Visit(this);
         }
     }
diff --git a/Implab.ServiceHost/Unity/IDependencyReference.cs b/Implab.ServiceHost/Unity/IDependencyReference.cs
--- a/Implab.ServiceHost/Unity/IDependencyReference.cs
+++ b/Implab.ServiceHost/Unity/IDependencyReference.cs
@@ -1,8 +1,10 @@
 namespace Implab.ServiceHost.Unity {
     public interface IDependencyReference {
 
-        string TypeName { get; set; }
+        string TypeName { get; }
+
+        bool Optional { get; }
         
-        string DependencyName { get; set; }
+        string DependencyName { get; }
     }
 }
\ No newline at end of file
diff --git a/Implab.ServiceHost/Unity/IInjectionArray.cs b/Implab.ServiceHost/Unity/IInjectionArray.cs
new file mode 100644
--- /dev/null
+++ b/Implab.ServiceHost/Unity/IInjectionArray.cs
@@ -0,0 +1,12 @@
+using System.Collections.Generic;
+
+namespace Implab.ServiceHost.Unity
+{
+    public interface IArrayInjectionParameter {
+
+        string TypeName { get; }
+
+        IEnumerable<IInjectionParameter> Items { get; }
+         
+    }
+}
\ No newline at end of file
diff --git a/Implab.ServiceHost/Unity/IInjectionParameter.cs b/Implab.ServiceHost/Unity/IInjectionParameter.cs
new file mode 100644
--- /dev/null
+++ b/Implab.ServiceHost/Unity/IInjectionParameter.cs
@@ -0,0 +1,5 @@
+namespace Implab.ServiceHost.Unity {
+    public interface IInjectionParameter {
+        void Visit(InjectionValueBuilder builder);
+    }
+}
\ No newline at end of file
diff --git a/Implab.ServiceHost/Unity/ITextValue.cs b/Implab.ServiceHost/Unity/ITextValue.cs
--- a/Implab.ServiceHost/Unity/ITextValue.cs
+++ b/Implab.ServiceHost/Unity/ITextValue.cs
@@ -1,5 +1,6 @@
 namespace Implab.ServiceHost.Unity {
     public interface ITextValue {
+
         string TypeName { get; }
 
         string Value { get; }
diff --git a/Implab.ServiceHost/Unity/InjectionParameterElement.cs b/Implab.ServiceHost/Unity/InjectionParameterElement.cs
--- a/Implab.ServiceHost/Unity/InjectionParameterElement.cs
+++ b/Implab.ServiceHost/Unity/InjectionParameterElement.cs
@@ -2,11 +2,11 @@ using System;
 using System.Xml.Serialization;
 
 namespace Implab.ServiceHost.Unity {
-    public abstract class InjectionParameterElement {
+    public abstract class InjectionParameterElement : IInjectionParameter {
         
         [XmlAttribute("type")]
         public string TypeName { get; set; }
 
-        internal abstract void Visit(InjectionValueBuilder builder);
+        public abstract void Visit(InjectionValueBuilder builder);
     }
 }
\ No newline at end of file
diff --git a/Implab.ServiceHost/Unity/SerializedElement.cs b/Implab.ServiceHost/Unity/SerializedElement.cs
--- a/Implab.ServiceHost/Unity/SerializedElement.cs
+++ b/Implab.ServiceHost/Unity/SerializedElement.cs
@@ -21,6 +21,8 @@ namespace Implab.ServiceHost.Unity
             }
         }
 
+        public string TypeName => throw new NotImplementedException();
+
         public override void Visit(ContainerBuilder context) {
             context.Visit(this);
         }
@@ -33,5 +35,9 @@ namespace Implab.ServiceHost.Unity
 
             throw new Exception("No content found, expected XML document");
         }
+
+        public void Visit(InjectionValueBuilder builder) {
+            throw new NotImplementedException();
+        }
     }
 }
\ No newline at end of file
diff --git a/Implab.ServiceHost/Unity/SerializedParameterElement.cs b/Implab.ServiceHost/Unity/SerializedParameterElement.cs
--- a/Implab.ServiceHost/Unity/SerializedParameterElement.cs
+++ b/Implab.ServiceHost/Unity/SerializedParameterElement.cs
@@ -21,7 +21,7 @@ namespace Implab.ServiceHost.Unity
             throw new Exception("No content found, expected XML document");
         }
 
-        internal override void Visit(InjectionValueBuilder builder) {
+        public override void Visit(InjectionValueBuilder builder) {
             builder.Visit(this);
         }
     }
diff --git a/Implab.ServiceHost/Unity/ValueParameterElement.cs b/Implab.ServiceHost/Unity/ValueParameterElement.cs
--- a/Implab.ServiceHost/Unity/ValueParameterElement.cs
+++ b/Implab.ServiceHost/Unity/ValueParameterElement.cs
@@ -6,7 +6,7 @@ namespace Implab.ServiceHost.Unity {
         [XmlAttribute("value")]
         public string Value { get; set; }
 
-        internal override void Visit(InjectionValueBuilder builder) {
+        public override void Visit(InjectionValueBuilder builder) {
             builder.Visit(this);
         }
     }