Communication options with WCF - Part 1

using System;
using System.Collections.Generic;
using System.Text;
using System.ServiceModel;
using System.Threading;

namespace AGVControllerD
{
    [ServiceContract(Session = true, CallbackContract = typeof(IMoveToCallback))]
    public interface IAGVControl
    {
        [OperationContract(IsInitiating = true, IsTerminating = false)]
        int AcquireVehicle();
        [OperationContract(IsTerminating = true, IsInitiating = false)]
        void ReleaseVehicle();
        [OperationContract(IsOneWay=true)]
        void MoveTo(int location);
        [OperationContract]
        void Load();
        [OperationContract]
        void Unload();
    }
    //What the client needs to implement
    public interface IMoveToCallback
    {
        [OperationContract(IsOneWay = true)]
        void MoveDone(int location);
    }

    [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)]
    public class AGVControl : IAGVControl
    {
        private IMoveToCallback callback = null;
        public AGVControl()
        {
            callback = OperationContext.Current.GetCallbackChannel<IMoveToCallback>();
        }
        public int AcquireVehicle()
        {
            int vehicleID = 0;
            return vehicleID;
        }
        public void ReleaseVehicle()
        {
            //place vehicle back in the pool
        }
        public void MoveTo(int location)
        {
            //This takes a long time...
            Thread.Sleep(5000);
            //Send a response
            callback.MoveDone(location);
        }
        public void Load()
        {
            //load it
        }
        public void Unload()
        {
            //unload it
        }
    }
}