DocumentStoreRegistry.cs

    public class DocumentStoreRegistry : Registry
    {
        public DocumentStoreRegistry()
        {
            For<IDocumentStore>().Singleton()
                .AddInstances(_ =>
                              _.ConstructedBy(ctor =>
                                  {
                                      var store = new DocumentStore { Url = ConfigurationManager.AppSettings["RAVENHQ_CONNECTION_STRING"] };
                                      store.Initialize();
                                      return store;
                                  }));

            For<IDocumentSession>().HttpContextScoped()
                .AddInstances(_ => _.ConstructedBy(ctor => ctor.GetInstance<RavenDocumentSession>().GetSession()));
        }
    }

RavenDocumentSession.cs

    public class RavenDocumentSession : IDisposable
    {
        readonly IDocumentStore _store;
        IDocumentSession _session;

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

        public IDocumentSession GetSession()
        {
            _session = _store.OpenSession();
            return _session;
        }

        public void Dispose()
        {
            _session.SaveChanges();
        }
    }