Some pre-requisites for for Razor build server

src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.props

@@ -29,9 +29,10 @@
     
     <TaskFolder Condition=" '$(MSBuildRuntimeType)' == 'Core' ">netstandard2.0</TaskFolder>
     <TaskFolder Condition=" '$(MSBuildRuntimeType)' != 'Core' ">net46</TaskFolder>
-    <TaskAssembly>$(_RazorMSBuildRoot)\tasks\$(TaskFolder)\Microsoft.AspNetCore.Razor.Tasks.dll</TaskAssembly>
+    
+    <_RazorTaskAssembly Condition="'$(_RazorTaskAssembly)'==''">$(_RazorMSBuildRoot)\tasks\$(TaskFolder)\Microsoft.AspNetCore.Razor.Tasks.dll</_RazorTaskAssembly>
   </PropertyGroup>
 
-  <UsingTask TaskName="Microsoft.AspNetCore.Razor.Tasks.RazorGenerate" AssemblyFile="$(TaskAssembly)" />
-  <UsingTask TaskName="Microsoft.AspNetCore.Razor.Tasks.RazorTagHelper" AssemblyFile="$(TaskAssembly)" />
+  <UsingTask TaskName="Microsoft.AspNetCore.Razor.Tasks.RazorGenerate" AssemblyFile="$(_RazorTaskAssembly)" />
+  <UsingTask TaskName="Microsoft.AspNetCore.Razor.Tasks.RazorTagHelper" AssemblyFile="$(_RazorTaskAssembly)" />
 </Project>

src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.targets

@@ -114,6 +114,7 @@
       Debug="$(_RazorDebugTagHelperTask)"
       DebugTool="$(_RazorDebugTagHelperTool)"
       ToolAssembly="$(_RazorTagHelperToolAssembly)"
+      ServerAssembly="$(_RazorBuildServerAssembly)"
       Assemblies="@(RazorReferencePath)"
       TagHelperManifest="$(_RazorTagHelperOutputCache)">
       <Output

src/Microsoft.AspNetCore.Razor.Tasks/DotnetToolTask.cs

@@ -62,6 +62,11 @@ namespace Microsoft.AspNetCore.Razor.Tasks
                 }
             }
 
+            if (TryExecuteOnServer(out var result))
+            {
+                return result;
+            }
+
             return base.Execute();
         }
 
@@ -76,5 +81,11 @@ namespace Microsoft.AspNetCore.Razor.Tasks
                 base.LogToolCommand(message);
             }
         }
+
+        protected virtual bool TryExecuteOnServer(out bool result)
+        {
+            result = false;
+            return false;
+        }
     }
 }

src/Microsoft.AspNetCore.Razor.Tasks/RazorTagHelper.cs

@@ -16,7 +16,9 @@ namespace Microsoft.AspNetCore.Razor.Tasks
         [Output]
         [Required]
         public string TagHelperManifest { get; set; }
-        
+
+        public string ServerAssembly { get; set; }
+
         protected override bool SkipTaskExecution()
         {
             if (Assemblies.Length == 0)

src/Microsoft.AspNetCore.Razor.Tools/Application.cs

@@ -8,7 +8,7 @@ using System.Reflection;
 using System.Threading;
 using Microsoft.Extensions.CommandLineUtils;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal class Application : CommandLineApplication
     {

src/Microsoft.AspNetCore.Razor.Tools/Client.cs

@@ -8,7 +8,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CommandLine;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal abstract class Client : IDisposable
     {

src/Microsoft.AspNetCore.Razor.Tools/CommandBase.cs

@@ -6,7 +6,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.CommandLineUtils;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal abstract class CommandBase : CommandLineApplication
     {

src/Microsoft.AspNetCore.Razor.Tools/CompilerHost.cs

@@ -5,7 +5,7 @@ using System.Collections.Generic;
 using System.Threading;
 using Microsoft.CodeAnalysis.CommandLine;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal abstract class CompilerHost
     {

src/Microsoft.AspNetCore.Razor.Tools/Connection.cs

@@ -6,7 +6,7 @@ using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal abstract class Connection : IDisposable
     {

src/Microsoft.AspNetCore.Razor.Tools/ConnectionHost.cs

@@ -7,7 +7,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CommandLine;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     // Heavily influenced by:
     // https://github.com/dotnet/roslyn/blob/14aed138a01c448143b9acf0fe77a662e3dfe2f4/src/Compilers/Server/VBCSCompiler/NamedPipeClientConnection.cs#L17

src/Microsoft.AspNetCore.Razor.Tools/ConnectionResult.cs

@@ -3,7 +3,7 @@
 
 using System;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal struct ConnectionResult
     {

src/Microsoft.AspNetCore.Razor.Tools/DebugMode.cs

@@ -6,7 +6,7 @@ using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal static class DebugMode
     {

src/Microsoft.AspNetCore.Razor.Tools/DiscoverCommand.cs

@@ -16,7 +16,7 @@ using Microsoft.Extensions.CommandLineUtils;
 using Microsoft.VisualStudio.LanguageServices.Razor;
 using Newtonsoft.Json;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal class DiscoverCommand : CommandBase
     {

src/Microsoft.AspNetCore.Razor.Tools/EventBus.cs

@@ -3,7 +3,7 @@
 
 using System;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal abstract class EventBus
     {

src/Microsoft.AspNetCore.Razor.Tools/Memory.cs

@@ -1,7 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal static class Memory
     {

src/Microsoft.AspNetCore.Razor.Tools/MutexName.cs

@@ -1,7 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal static class MutexName
     {

src/Microsoft.AspNetCore.Razor.Tools/PipeName.cs

@@ -7,7 +7,7 @@ using System.Runtime.InteropServices;
 using System.Security.Cryptography;
 using System.Text;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal static class PipeName
     {

src/Microsoft.AspNetCore.Razor.Tools/Program.cs

@@ -4,7 +4,7 @@
 using System;
 using System.Threading;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal static class Program
     {

src/Microsoft.AspNetCore.Razor.Tools/RequestDispatcher.cs

@@ -11,7 +11,7 @@ using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CommandLine;
 using Microsoft.CodeAnalysis.CompilerServer;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     // Heavily influenced by:
     // https://github.com/dotnet/roslyn/blob/14aed138a01c448143b9acf0fe77a662e3dfe2f4/src/Compilers/Server/ServerShared/ServerDispatcher.cs#L15

src/Microsoft.AspNetCore.Razor.Tools/ServerCommand.cs

@@ -5,7 +5,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.CommandLineUtils;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal class ServerCommand : CommandBase
     {

src/Microsoft.AspNetCore.Razor.Tools/ShutdownCommand.cs

@@ -8,7 +8,7 @@ using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CommandLine;
 using Microsoft.Extensions.CommandLineUtils;
 
-namespace Microsoft.AspNetCore.Razor.TagHelperTool
+namespace Microsoft.AspNetCore.Razor.Tools
 {
     internal class ShutdownCommand : CommandBase
     {