Injecting Message Information in Lokad CQRS v2

ExtendImmutableEnvelope.cs

    public static class ExtendImmutableEnvelope
    {
        public static Guid GetGuid(this ImmutableEnvelope envelope, string key)
        {
            return Get(envelope, key, s =>
            {
                Guid result;
                return Guid.TryParse(s, out result) == false ? Guid.Empty : result;
            });
        }

        public static int GetInt(this ImmutableEnvelope envelope, string key)
        {
            return Get(envelope, key, s =>
            {
                int result;
                return int.TryParse(s, out result) == false ? 0 : result;
            });
        }

        public static string GetString(this ImmutableEnvelope envelope, string key)
        {
            return Get(envelope, key, s => s);
        }

        private static T Get<T>(this ImmutableEnvelope envelope, string key, Func<string, T> convert)
        {
            ImmutableAttribute attribute =
                envelope.GetAllAttributes().Where(a => a.Key == key).FirstOrDefault();

            return convert(attribute == null ? string.Empty : attribute.Value);
        }
    }

MyCommandHandler.cs

    public class MyCommandHandler : Define.Handle<MyCommand>
    {
        private readonly Func<MyCustomContext> contextFactory;

        public MyCommandHandler(Func<MyCustomContext> contextFactory)
        {
            this.contextFactory = contextFactory;
        }

        #region Implementation of IConsume<in Command>

        public void Consume(MyCommand message)
        {
            var context = contextFactory();

            Console.Out.WriteLine(context.TenantId);
        }

        #endregion
    }

MyCustomContext.cs

    [ProtoContract]
    [DataContract]
    public class MyCustomContext
    {
        [ProtoMember(1)]
        [DataMember(Order = 1)]
        public int TenantId { get; set; }

        public static MyCustomContext Factory(ImmutableEnvelope envelope, ImmutableMessage message)
        {
            return new MyCustomContext
            {
                TenantId = envelope.GetInt("TenantId")
            };
        }
    }

Sending.cs

IMessageSender sender is injected;

sender.SendOne(new MyCommand(), b => b.AddString("TenantId", "123"));