双方向通信のためのインターフェース設計

namespace SOA.WCF.Contract
{
    [ServiceContract(CallbackContract = typeof(ISumResultHandler))]
    public interface IArithmeticService
    {
        [OperationContract(IsOneWay = true)]
        void ExecuteAddition(int operandA, int operandB);
    }
}

コールバック契約の定義

namespace SOA.WCF.Contract
{
    public interface ISumResultHandler
    {
        [OperationContract(IsOneWay = true)]
        void NotifyResult(int leftValue, int rightValue, int calculatedTotal);
    }
}

サービス実装ロジック

namespace SOA.WCF.Service
{
    public class MathOperationService : IArithmeticService
    {
        public void ExecuteAddition(int operandA, int operandB)
        {
            int total = operandA + operandB;
            var callbackChannel = OperationContext.Current.GetCallbackChannel<ISumResultHandler>();
            callbackChannel.NotifyResult(operandA, operandB, total);
        }
    }
}

ネットワーク構成設定

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <system.serviceModel>
        <behaviors>
            <serviceBehaviors>
                <behavior name="ArithmeticBehavior">
                    <serviceDebug includeExceptionDetailInFaults="false"/>
                    <serviceMetadata httpGetEnabled="false"/>
                    <serviceThrottling maxConcurrentCalls="500" maxConcurrentInstances="500"/>
                </behavior>
            </serviceBehaviors>
        </behaviors>
        <bindings>
            <netTcpBinding>
                <binding name="secureTcpBinding">
                    <security mode="Transport">
                        <transport clientCredentialType="Windows"/>
                    </security>
                </binding>
            </netTcpBinding>
        </bindings>
        <services>
            <service name="SOA.WCF.Service.MathOperationService" behaviorConfiguration="ArithmeticBehavior">
                <host>
                    <baseAddresses>
                        <add baseAddress="net.tcp://localhost:8080/MathService"/>
                    </baseAddresses>
                </host>
                <endpoint address="" binding="netTcpBinding" bindingConfiguration="secureTcpBinding" contract="SOA.WCF.Contract.IArithmeticService"/>
                <endpoint address="mex" binding="mexTcpBinding" contract="IMetadataExchange"/>
            </service>
        </services>
    </system.serviceModel>
</configuration>

サービス起動処理

public static void InitializeHosts()
{
    var serviceHosts = new[]
    {
        new ServiceHost(typeof(MathOperationService))
    };

    foreach (var host in serviceHosts)
    {
        host.Opened += (s, e) => Console.WriteLine($"サービスホスト開始: {host.BaseAddresses[0]}");
        host.Open();
    }

    Console.WriteLine("終了するには任意のキーを入力");
    Console.ReadKey();

    foreach (var host in serviceHosts)
    {
        host.Close();
    }
}

クライアント実装

class Program
{
    static void Main(string[] args)
    {
        using (var client = new ArithmeticServiceClient(new InstanceContext(new ResultObserver())))
        {
            client.ExecuteAddition(7, 13);
        }
        Console.ReadLine();
    }
}

コールバックハンドラ

class ResultObserver : ISumResultHandler
{
    public void NotifyResult(int leftValue, int rightValue, int calculatedTotal)
    {
        Console.WriteLine($"演算結果: {leftValue} + {rightValue} = {calculatedTotal}");
    }
}

サービス側からのコールバック呼び出しにより、クライアント側の処理が実行され双方向通信が実現されます。