@@ -0,0 +1,14 @@
+using System;
+
+namespace uhttpsharp.Attributes
+{
+    /// <summary>
+    /// Marks a controller method argmuent 
+    /// as an argument that may be null.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = false)]
+    public class NullableAttribute : Attribute
+    {
+        
+    }
+}
@@ -0,0 +1,32 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using uhttpsharp.Handlers;
+
+namespace uhttpsharp.Controllers
+{
+    public class ErrorContainer : IErrorContainer
+    {
+        private readonly IList<string> _errors = new List<string>();
+
+        public void Log(string description)
+        {
+            _errors.Add(description);
+        }
+
+        public IEnumerable<string> Errors
+        {
+            get { return _errors; }
+        }
+        public bool Any
+        {
+            get { return _errors.Count != 0; }
+        }
+        public Task<IControllerResponse> GetResponse()
+        {
+            return
+                Task.FromResult<IControllerResponse>(new RenderResponse(HttpResponseCode.MethodNotAllowed,
+                    new {Message = string.Join(", ", _errors)}));
+        }
+    }
+}
@@ -0,0 +1,19 @@
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using uhttpsharp.Handlers;
+
+namespace uhttpsharp.Controllers
+{
+    public interface IErrorContainer
+    {
+
+        void Log(string description);
+
+        IEnumerable<string> Errors { get; }
+
+        bool Any { get; }
+
+        Task<IControllerResponse> GetResponse();
+
+    }
+}
@@ -0,0 +1,9 @@
+namespace uhttpsharp.Controllers
+{
+    public interface IValidate
+    {
+
+        void Validate(IErrorContainer container);
+
+    }
+}