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diff --git a/src/csharp/Grpc.Tools/ProtoCompilerOutputs.cs b/src/csharp/Grpc.Tools/ProtoCompilerOutputs.cs
new file mode 100644
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+++ b/src/csharp/Grpc.Tools/ProtoCompilerOutputs.cs
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+#region Copyright notice and license
+
+// Copyright 2018 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#endregion
+
+using System.Collections.Generic;
+using Microsoft.Build.Framework;
+using Microsoft.Build.Utilities;
+
+namespace Grpc.Tools
+{
+    public class ProtoCompilerOutputs : Task
+    {
+        /// <summary>
+        /// Code generator. Currently supported are "csharp", "cpp".
+        /// </summary>
+        [Required]
+        public string Generator { get; set; }
+
+        /// <summary>
+        /// All Proto files in the project. The task computes possible outputs
+        /// from these proto files, and returns them in the PossibleOutputs list.
+        /// Not all of these might be actually produced by protoc; this is dealt
+        /// with later in the ProtoCompile task which returns the list of
+        /// files actually produced by the compiler.
+        /// </summary>
+        [Required]
+        public ITaskItem[] ProtoBuf { get; set; }
+
+        /// <summary>
+        /// Output items per each potential output. We do not look at existing
+        /// cached dependency even if they exist, since file may be refactored,
+        /// affecting whether or not gRPC code file is generated from a given proto.
+        /// Instead, all potentially possible generated sources are collected.
+        /// It is a wise idea to generate empty files later for those potentials
+        /// that are not actually created by protoc, so the dependency checks
+        /// result in a minimal recompilation. The Protoc task can output the
+        /// list of files it actually produces, given right combination of its
+        /// properties.
+        /// Output items will have the Source metadata set on them:
+        ///     <ItemName Include="MyProto.cs" Source="my_proto.proto" />
+        /// </summary>
+        [Output]
+        public ITaskItem[] PossibleOutputs { get; private set; }
+
+        public override bool Execute()
+        {
+            var generator = GeneratorServices.GetForLanguage(Generator, Log);
+            if (generator == null)
+            {
+                // Error already logged, just return.
+                return false;
+            }
+
+            // Get language-specific possible output. The generator expects certain
+            // metadata be set on the proto item.
+            var possible = new List<ITaskItem>();
+            foreach (var proto in ProtoBuf)
+            {
+                var outputs = generator.GetPossibleOutputs(proto);
+                foreach (string output in outputs)
+                {
+                    var ti = new TaskItem(output);
+                    ti.SetMetadata(Metadata.Source, proto.ItemSpec);
+                    possible.Add(ti);
+                }
+            }
+            PossibleOutputs = possible.ToArray();
+
+            return !Log.HasLoggedErrors;
+        }
+    };
+}