Added the MySparkApp.

Author: daisukenishino2

Azure/DotNet4ApacheSpark/MySparkApp/MySparkApp.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.30621.155
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MySparkApp", "MySparkApp\MySparkApp.csproj", "{7E78FDB9-921D-41AD-9703-66BC71261450}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{7E78FDB9-921D-41AD-9703-66BC71261450}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{7E78FDB9-921D-41AD-9703-66BC71261450}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{7E78FDB9-921D-41AD-9703-66BC71261450}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{7E78FDB9-921D-41AD-9703-66BC71261450}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {82AFA3F8-C83A-4162-BCD8-4FE72D7535CB}
+	EndGlobalSection
+EndGlobal

Azure/DotNet4ApacheSpark/MySparkApp/MySparkApp/MySparkApp.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Spark" Version="1.0.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <None Update="input.txt">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+</Project>

Azure/DotNet4ApacheSpark/MySparkApp/MySparkApp/Program.cs

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+using System;
+
+using Microsoft.Spark.Sql;
+using static Microsoft.Spark.Sql.Functions;
+
+namespace MySparkApp
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            //Console.WriteLine("Hello World!");
+
+            // Create Spark session
+            SparkSession spark =
+                SparkSession
+                    .Builder()
+                    .AppName("word_count_sample")
+                    .GetOrCreate();
+
+            // Create initial DataFrame
+            string filePath = args[0];
+            DataFrame dataFrame = spark.Read().Text(filePath);
+
+            //Count words
+            DataFrame words =
+                dataFrame
+                    .Select(Split(Col("value"), " ").Alias("words"))
+                    .Select(Explode(Col("words")).Alias("word"))
+                    .GroupBy("word")
+                    .Count()
+                    .OrderBy(Col("count").Desc());
+
+            // Display results
+            words.Show();
+
+            // Stop Spark session
+            spark.Stop();
+        }
+    }
+}

Azure/DotNet4ApacheSpark/MySparkApp/MySparkApp/input.txt

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+Hello World
+This .NET app uses .NET for Apache Spark
+This .NET app counts words with Apache Spark