CAST supports Elasticsearch via its NoSQL for .NET extension. Details about how this support is provided for .NET source code is discussed below.

class HighLevel
{
        public void UsingConnectionPool()
        {            var uris = new[]
	             {
	                new Uri("http://localhost:9200"),
	                new Uri("http://localhost:9201"), 
	               new Uri("http://localhost:9202"), 
	             };
	            var connectionPool = new SniffingConnectionPool(uris);
	            var settings = new ConnectionSettings(connectionPool)
		                .DefaultIndex("people");
	            var client = new ElasticClient(settings);
        }
}

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name="resizer" type="ImageResizer.ResizerSection,ImageResizer" requirePermission="false" />
    <section name="quartz" type="System.Configuration.NameValueSectionHandler, System, Version=1.0.5000.0,Culture=neutral, PublicKeyToken=b77a5c561934e089" />
    <section name="rockConfig" type="Rock.Configuration.RockConfig, Rock" />
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  </configSections>
  <appSettings>
    <add key="baseUrl" value="http://127.0.0.1:9200" />
    <add key="AllowDuplicateGroupMembers" value="false" />
    <add key="EnableRedisCacheCluster" value="False" />
    <add key="RedisPassword" value="" />
    <add key="RedisEndpointList" value="" />
    <add key="RedisDatabaseNumber" value="0" />
    <add key="CacheManagerEnableStatistics" value="False" />
  </appSettings>

  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Http" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-5.2.3.0" newVersion="5.2.3.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Net.Http.Formatting" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-5.2.3.0" newVersion="5.2.3.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.IdentityModel.Tokens" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-5.2.1.0" newVersion="5.2.1.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.Owin" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.Owin.Security" publicKeyToken="31bf3856ad364e35" culture="neutral" />
          <bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.IdentityModel.Protocol.Extensions" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-1.0.40306.1554" newVersion="1.0.40306.1554" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.AspNetCore.DataProtection.Abstractions" publicKeyToken="adb9793829ddae60" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
  <system.codedom>
    <compilers>
      <compiler extension=".cs" language="c#;cs;csharp" warningLevel="4" compilerOptions="/langversion:7.3 /nowarn:1659;1699;1701" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=3.6.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
        <providerOption name="UseAspNetSettings" value="false" />
      </compiler>
    </compilers>
  </system.codedom>
</configuration>

public void Indexing()
{
            var person = new Person
            {
                Id = 1,
                FirstName = "Martijn",
                LastName = "Laarman"
            };
            var ndexResponse = client.IndexDocument(person); //<1>
}

public async Task IndexingAsync()
{            var person = new Person
            {
                Id = 2,
                FirstName = "Jack",
                LastName = "Mas" 
           };
           var asyncIndexResponse = await client.IndexDocumentAsync(person); 
}

public static bool updateDocument(string searchID, string first_name, string last_name)
{
		bool status;
           	//Update by Partial Document
               var response = client.Update<DocumentAttributes, UpdateDocumentAttributes>(searchID, d => d
                .Index(index)
                .Doc(new UpdateDocumentAttributes
                {
                    FirstName = first_name,
                    LastName = last_name
                 }));            
}

public void SearchingOnDefaultIndex()        
{
	var searchResponse = client.Search<Person>(s => s
                .From(0)
                .Size(10)
                .Query(q => q
                     .Match(m => m
                        .Field(f => f.FirstName)
                        .Query("Martijn")
                     )
                )
            );
            var people = searchResponse.Documents;        
}

public static bool deleteDocument(string index, string searchID)        
{
		bool status;
            	var response = client.Delete<DocumentAttributes>(searchID, d => d
                	.Index(index));
		if (response.IsValid)
		{
	             status = true;
            	}
	       else
	       {
	                status = false;
               }
            return status;
}   

public void BulkOperations()        
{
            var people = new object[]
            {
                new { index = new { _index = "people", _type = "person", _id = "1"  }},
                new { FirstName = "Martijn", LastName = "Laarman" },
                new { index = new { _index = "people", _type = "person", _id = "2"  }},
                new { FirstName = "Greg", LastName = "Marzouka" },
                new { index = new { _index = "people", _type = "person", _id = "3"  }},
                new { FirstName = "Russ", LastName = "Cam" },
             };
            var ndexResponse = lowlevelClient.Bulk<StringResponse>(PostData.MultiJson(people));
            string responseStream = ndexResponse.Body;
}

public void BulkOperationsUsingFluentDSL ()
{
            var result = client.Bulk(b => b
            .Index<Person>(i => i
                .Document(new Person {Id = 2})
             )   
             .Create<Person>(c => c
                .Document(new Person { Id = 3 })
            )
            .Delete<Person>(d => d
                .Document(new Person { Id = 4 })
            ));
}