Index: Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Activities/HydraRingActivity.cs
===================================================================
diff -u
--- Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Activities/HydraRingActivity.cs	(revision 0)
+++ Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Activities/HydraRingActivity.cs	(revision e4613b1908b45105cdc5be7f3fb2f4fad823473e)
@@ -0,0 +1,54 @@
+// Copyright (C) Stichting Deltares 2016. All rights reserved.
+//
+// This file is part of Ringtoets.
+//
+// Ringtoets is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+//
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+using System;
+using Core.Common.Base.Service;
+
+namespace Ringtoets.HydraRing.Calculation.Activities
+{
+    /// <summary>
+    /// <see cref="Activity"/> for running calculations via Hydra-Ring.
+    /// </summary>
+    public abstract class HydraRingActivity : Activity
+    {
+        private readonly Action beforeRunAction;
+
+        /// <summary>
+        /// Creates a new instance of the <see cref="HydraRingActivity"/> class.
+        /// </summary>
+        /// <param name="beforeRunAction">The action to perform before running a Hydra-Ring calculation (like clearing output, validation, etc.).</param>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="beforeRunAction"/> is <c>null</c>.</exception>
+        protected HydraRingActivity(Action beforeRunAction)
+        {
+            if (beforeRunAction == null)
+            {
+                throw new ArgumentNullException("beforeRunAction", @"The action to perform before run should be set.");
+            }
+
+            this.beforeRunAction = beforeRunAction;
+        }
+
+        protected override void OnRun()
+        {
+            beforeRunAction();
+        }
+    }
+}
Index: Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Ringtoets.HydraRing.Calculation.csproj
===================================================================
diff -u -r74f9fae7e26c7ba15c1ef5681c51acf842f76122 -re4613b1908b45105cdc5be7f3fb2f4fad823473e
--- Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Ringtoets.HydraRing.Calculation.csproj	(.../Ringtoets.HydraRing.Calculation.csproj)	(revision 74f9fae7e26c7ba15c1ef5681c51acf842f76122)
+++ Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Ringtoets.HydraRing.Calculation.csproj	(.../Ringtoets.HydraRing.Calculation.csproj)	(revision e4613b1908b45105cdc5be7f3fb2f4fad823473e)
@@ -48,6 +48,7 @@
       <Link>Properties\GlobalAssembly.cs</Link>
     </Compile>
     <Compile Include="Activities\ExceedanceProbabilityCalculationActivity.cs" />
+    <Compile Include="Activities\HydraRingActivity.cs" />
     <Compile Include="Data\HydraRingBreakWater.cs" />
     <Compile Include="Data\HydraRingSection.cs" />
     <Compile Include="Data\HydraRingForelandPoint.cs" />
Index: Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Activities/HydraRingActivityTest.cs
===================================================================
diff -u
--- Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Activities/HydraRingActivityTest.cs	(revision 0)
+++ Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Activities/HydraRingActivityTest.cs	(revision e4613b1908b45105cdc5be7f3fb2f4fad823473e)
@@ -0,0 +1,51 @@
+// Copyright (C) Stichting Deltares 2016. All rights reserved.
+//
+// This file is part of Ringtoets.
+//
+// Ringtoets is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+//
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+using System;
+using NUnit.Framework;
+using Ringtoets.HydraRing.Calculation.Activities;
+
+namespace Ringtoets.HydraRing.Calculation.Test.Activities
+{
+    [TestFixture]
+    public class HydraRingActivityTest
+    {
+        [Test]
+        public void Constructor_BeforeRunActionNull_ThrowsArgumentNullException()
+        {
+            // Call
+            TestDelegate test = () => new TestHydraRingActivity(null);
+
+            // Assert
+            var paramName = Assert.Throws<ArgumentNullException>(test).ParamName;
+            Assert.AreEqual("beforeRunAction", paramName);
+        }
+
+        private class TestHydraRingActivity : HydraRingActivity
+        {
+            public TestHydraRingActivity(Action beforeRunAction) : base(beforeRunAction) {}
+
+            protected override void OnCancel() {}
+
+            protected override void OnFinish() {}
+        }
+    }
+}
\ No newline at end of file
Index: Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Ringtoets.HydraRing.Calculation.Test.csproj
===================================================================
diff -u -r74f9fae7e26c7ba15c1ef5681c51acf842f76122 -re4613b1908b45105cdc5be7f3fb2f4fad823473e
--- Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Ringtoets.HydraRing.Calculation.Test.csproj	(.../Ringtoets.HydraRing.Calculation.Test.csproj)	(revision 74f9fae7e26c7ba15c1ef5681c51acf842f76122)
+++ Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Ringtoets.HydraRing.Calculation.Test.csproj	(.../Ringtoets.HydraRing.Calculation.Test.csproj)	(revision e4613b1908b45105cdc5be7f3fb2f4fad823473e)
@@ -61,6 +61,7 @@
   <ItemGroup>
     <Compile Include="Activities\ExceedanceProbabilityCalculationActivityTest.cs" />
     <Compile Include="Activities\HydraRingActivityFactoryTest.cs" />
+    <Compile Include="Activities\HydraRingActivityTest.cs" />
     <Compile Include="Data\HydraRingBreakWaterTest.cs" />
     <Compile Include="Data\HydraRingForelandPointTest.cs" />
     <Compile Include="Data\Input\Overtopping\HydraRingRoughnessProfilePointTest.cs" />
Index: Ringtoets/Piping/src/Ringtoets.Piping.Service/PipingCalculationActivity.cs
===================================================================
diff -u -r74e3dea657b90b371e265914bee337c76e509d93 -re4613b1908b45105cdc5be7f3fb2f4fad823473e
--- Ringtoets/Piping/src/Ringtoets.Piping.Service/PipingCalculationActivity.cs	(.../PipingCalculationActivity.cs)	(revision 74e3dea657b90b371e265914bee337c76e509d93)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Service/PipingCalculationActivity.cs	(.../PipingCalculationActivity.cs)	(revision e4613b1908b45105cdc5be7f3fb2f4fad823473e)
@@ -57,7 +57,7 @@
             }
 
             LogMessages.Clear();
-            calculation.Output = null;
+            calculation.ClearOutput();;
 
             PipingCalculationService.Calculate(calculation);
             PipingSemiProbabilisticCalculationService.Calculate(calculation);