diff --git a/Implab/IPromise.cs b/Implab/IPromise.cs
--- a/Implab/IPromise.cs
+++ b/Implab/IPromise.cs
@@ -7,10 +7,26 @@ namespace Implab
 {
     public interface IPromise<T>: IPromiseBase
     {
-        
+
+        T Join();
+
+        T Join(int timeout);
 
+        IPromise<T> Then(ResultHandler<T> success, ErrorHandler error);
+        IPromise<T> Then(ResultHandler<T> success, ErrorHandler<T> error);
+        IPromise<T> Then(ResultHandler<T> success);
+        IPromise<T> Error(ErrorHandler error);
+        IPromise<T> Error(ErrorHandler<T> error);
 
+        IPromise<T2> Map<T2>(ResultMapper<T,T2> mapper, ErrorHandler error);
+        IPromise<T2> Map<T2>(ResultMapper<T, T2> mapper);
 
+        IPromise<T2> Chain<T2>(ChainedOperation<T, T2> chained, ErrorHandler error);
+        IPromise<T2> Chain<T2>(ChainedOperation<T, T2> chained);
+
+        IPromise<T> Cancelled(Action handler);
+        IPromise<T> Finally(Action handler);
+        IPromise<T> Anyway(Action handler);
 
     }
 }
diff --git a/Implab/IPromiseBase.cs b/Implab/IPromiseBase.cs
--- a/Implab/IPromiseBase.cs
+++ b/Implab/IPromiseBase.cs
@@ -15,5 +15,9 @@ namespace Implab {
         bool IsResolved { get; }
 
         bool IsCancelled { get; }
+
+        IPromiseBase Then(Action success,ErrorHandler error);
+        IPromiseBase Then(Action success);
+
     }
 }
diff --git a/Implab/Parallels/ArrayTraits.cs b/Implab/Parallels/ArrayTraits.cs
--- a/Implab/Parallels/ArrayTraits.cs
+++ b/Implab/Parallels/ArrayTraits.cs
@@ -125,7 +125,7 @@ namespace Implab.Parallels {
             return iter.Promise;
         }
 
-        public static Promise<TDst[]> ChainedMap<TSrc, TDst>(this TSrc[] source, ChainedOperation<TSrc, TDst> transform, int threads) {
+        public static IPromise<TDst[]> ChainedMap<TSrc, TDst>(this TSrc[] source, ChainedOperation<TSrc, TDst> transform, int threads) {
             if (source == null)
                 throw new ArgumentNullException("source");
             if (transform == null)
diff --git a/Implab/Promise.cs b/Implab/Promise.cs
--- a/Implab/Promise.cs
+++ b/Implab/Promise.cs
@@ -191,7 +191,7 @@ namespace Implab {
         /// This handler will recieve an operation result as a parameter.</param>
         /// <param name="error">Handles an exception that may occur during the operation.</param>
         /// <returns>The new promise chained to this one.</returns>
-        public Promise<T> Then(ResultHandler<T> success, ErrorHandler error) {
+        public IPromise<T> Then(ResultHandler<T> success, ErrorHandler error) {
             if (success == null && error == null)
                 return this;
 
@@ -225,6 +225,16 @@ namespace Implab {
             return medium;
         }
 
+        public IPromiseBase Then(Action success,ErrorHandler error)
+        {
+            return Then(x => success(), error);
+        }
+
+        public IPromiseBase Then(Action success)
+        {
+            return Then(success);
+        }
+
         /// <summary>
         /// Adds new handlers to this promise.
         /// </summary>
@@ -232,7 +242,7 @@ namespace Implab {
         /// This handler will recieve an operation result as a parameter.</param>
         /// <param name="error">Handles an exception that may occur during the operation and returns the value which will be used as the result of the operation.</param>
         /// <returns>The new promise chained to this one.</returns>
-        public Promise<T> Then(ResultHandler<T> success, ErrorHandler<T> error) {
+        public IPromise<T> Then(ResultHandler<T> success, ErrorHandler<T> error) {
             if (success == null && error == null)
                 return this;
 
@@ -266,7 +276,7 @@ namespace Implab {
         }
 
 
-        public Promise<T> Then(ResultHandler<T> success) {
+        public IPromise<T> Then(ResultHandler<T> success) {
             if (success == null)
                 return this;
 
@@ -287,8 +297,8 @@ namespace Implab {
             return medium;
         }
 
-        public Promise<T> Error(ErrorHandler error) {
-            return Then(null, error);
+        public IPromise<T> Error(ErrorHandler error) {
+            return Then((ResultHandler<T>)null, error);
         }
 
         /// <summary>
@@ -299,7 +309,7 @@ namespace Implab {
         /// </remarks>
         /// <param name="handler">The error handler which returns the result of the promise.</param>
         /// <returns>New promise.</returns>
-        public Promise<T> Error(ErrorHandler<T> handler) {
+        public IPromise<T> Error(ErrorHandler<T> handler) {
             if (handler == null)
                 return this;
 
@@ -320,7 +330,7 @@ namespace Implab {
             return medium;
         }
 
-        public Promise<T> Anyway(Action handler) {
+        public IPromise<T> Anyway(Action handler) {
             if (handler == null)
                 return this;
 
@@ -358,7 +368,7 @@ namespace Implab {
         /// <param name="error">Обработчик ошибки. Данный обработчик получит
         /// исключение возникшее при выполнении операции.</param>
         /// <returns>Новое обещание, которое будет выполнено при выполнении исходного обещания.</returns>
-        public Promise<TNew> Map<TNew>(ResultMapper<T, TNew> mapper, ErrorHandler error) {
+        public IPromise<TNew> Map<TNew>(ResultMapper<T, TNew> mapper, ErrorHandler error) {
             if (mapper == null)
                 throw new ArgumentNullException("mapper");
 
@@ -385,7 +395,7 @@ namespace Implab {
             return chained;
         }
 
-        public Promise<TNew> Map<TNew>(ResultMapper<T, TNew> mapper) {
+        public IPromise<TNew> Map<TNew>(ResultMapper<T, TNew> mapper) {
             return Map(mapper, null);
         }
 
@@ -399,7 +409,7 @@ namespace Implab {
         /// <param name="error">Обработчик ошибки. Данный обработчик получит
         /// исключение возникшее при выполнении текуещй операции.</param>
         /// <returns>Новое обещание, которое будет выполнено по окончанию указанной аснхронной операции.</returns>
-        public Promise<TNew> Chain<TNew>(ChainedOperation<T, TNew> chained, ErrorHandler error) {
+        public IPromise<TNew> Chain<TNew>(ChainedOperation<T, TNew> chained, ErrorHandler error) {
 
             // проблема в том, что на момент связывания еще не начата асинхронная операция, поэтому нужно
             // создать посредника, к которому будут подвызяваться следующие обработчики.
@@ -437,11 +447,11 @@ namespace Implab {
             return medium;
         }
 
-        public Promise<TNew> Chain<TNew>(ChainedOperation<T, TNew> chained) {
+        public IPromise<TNew> Chain<TNew>(ChainedOperation<T, TNew> chained) {
             return Chain(chained, null);
         }
 
-        public Promise<T> Cancelled(Action handler) {
+        public IPromise<T> Cancelled(Action handler) {
             AddHandler(null, null, handler);
             return this;
         }
@@ -451,7 +461,7 @@ namespace Implab {
         /// </summary>
         /// <param name="handler">The handler that will be called anyway</param>
         /// <returns>self</returns>
-        public Promise<T> Finally(Action handler) {
+        public IPromise<T> Finally(Action handler) {
             if (handler == null)
                 throw new ArgumentNullException("handler");
             AddHandler(