using System;

using System.Collections.Generic;

using System.Threading.Tasks;

using System.Threading.Tasks.Dataflow;

​

public static class Program

{

    public static async Task Main()

    {

        var block2 = new ActionBlock<string[]>(parts =>

        {

            string completeMessage = String.Join(" ", parts);

            Console.WriteLine($"Processing message: {completeMessage}");

        });

​

        var parts = new List<string>();

        var block1 = new ActionBlock<string>(rawMessage =>

        {

            if (rawMessage is null) { block2.Complete(); return; }

            parts.Add(rawMessage);

            if (rawMessage.EndsWith("."))

            {

                block2.Post(parts.ToArray());

                parts.Clear();

            }

        });

​

        block1.Post("Hello");

        block1.Post("world.");

        block1.Post("The quick");

        block1.Post("brown fox.");

​

        block1.Post(null); // Signal that there are no more messages

        block1.Complete();

        await block2.Completion;

        Console.WriteLine("Processing terminated");

    }

}

​