Using RavenDB with ServiceStack

I read this post from Phillip Haydon on how to use NHibernate / RavenDB with ServiceStack.
I don't see the point of getting an IDocumentStore and opening a new session every time I need something from db, like this:

public class FooService : ServiceBase<Foo>
{
    public IDocumentStore RavenStore{ get; set; }

    protected override object Run(ProductFind request)
    {
        using (var session = RavenStore.OpenSession())
        {
            // Do Something...

            return new FooResponse{/*Object init*/};
        }
    }
}

Why can't I use one session for each request and when the request ends, commit the changes or roll them back according to the status of the response?

If my approach is fine, how can I implement it? here is my attempt:

I created this class:

    public class RavenSession : IRavenSession
    {
        #region Data Members

        private readonly IDocumentStore _store;
        private IDocumentSession _innerSession;

        #endregion

        #region Properties

        public IDocumentSession InnerSession
        {
            get { return _innerSession ?? (_innerSession = _store.OpenSession()); }
        }

        #endregion

        #region Ctor

        public RavenSession(IDocumentStore store)
        {
            _store = store;
        }

        #endregion

        #region Public Methods

        public void Commit()
        {
            if (_innerSession != null)
            {
                try
                {
                    InnerSession.SaveChanges();
                }
                finally
                {
                    InnerSession.Dispose();
                }
            }
        }

        public void Rollback()
        {
            if (_innerSession != null)
            {
                InnerSession.Dispose();
            }
        }

        #endregion

        #region IDocumentSession Delegation

        public ISyncAdvancedSessionOperation Advanced
        {
            get { return InnerSession.Advanced; }
        }

        public void Delete<T>(T entity)
        {
            InnerSession.Delete(entity);
        }

        public ILoaderWithInclude<object> Include(string path)
        {
            return InnerSession.Include(path);
        }

        public ILoaderWithInclude<T> Include<T, TInclude>(Expression<Func<T, object>> path)
        {
            return InnerSession.Include<T, TInclude>(path);
        }

        public ILoaderWithInclude<T> Include<T>(Expression<Func<T, object>> path)
        {
            return InnerSession.Include(path);
        }

        public T Load<T>(string id)
        {
            return InnerSession.Load<T>(id);
        }

        public T[] Load<T>(params string[] ids)
        {
            return InnerSession.Load<T>(ids);
        }

        public T Load<T>(ValueType id)
        {
            return InnerSession.Load<T>(id);
        }

        public T[] Load<T>(IEnumerable<string> ids)
        {
            return InnerSession.Load<T>(ids);
        }

        public IRavenQueryable<T> Query<T, TIndexCreator>() where TIndexCreator : AbstractIndexCreationTask, new()
        {
            return InnerSession.Query<T, TIndexCreator>();
        }

        public IRavenQueryable<T> Query<T>()
        {
            return InnerSession.Query<T>();
        }

        public IRavenQueryable<T> Query<T>(string indexName)
        {
            return InnerSession.Query<T>(indexName);
        }

        public void Store(dynamic entity, string id)
        {
            InnerSession.Store(entity, id);
        }

        public void Store(object entity, Guid etag, string id)
        {
            InnerSession.Store(entity, etag, id);
        }

        public void Store(object entity, Guid etag)
        {
            InnerSession.Store(entity, etag);
        }

        public void Store(dynamic entity)
        {
            InnerSession.Store(entity);
        }

        #endregion

    }

Now my service looks like this:

public class FooService : ServiceBase<Foo>
{
    public IRavenSession RavenSession { get; set; }

    protected override object Run(ProductFind request)
    {
        // Do Something with RavenSession...

        return new FooResponse {/*Object init*/};
    }
}

but I still need to find a way to find out when the request is completed to commit / rollback changes.
best way to find this with ResponseFilters:

public class AppHost : AppHostBase
{
    public AppHost()
        : base("", typeof (Foo).Assembly, typeof (FooService).Assembly)
    {
    }

    public override void Configure(Container container)
    {
        // Some Configuration...

        this.ResponseFilters.Add((httpReq, httpResp, respnseDto) =>
                                     {
                                         var currentSession = (RavenSession) this.Container.Resolve<IRavenSession>();

                                         if (!httpResp.IsErrorResponse())
                                         {
                                             currentSession.Commit();
                                         }
                                         else
                                         {
                                             currentSession.Rollback();
                                         }
                                     });

        // Some Configuration...
    }
}

I am sure there is a better way to do this, but how?