autofac 和 IObserver int T 的问题 ？

在asp.net mvc 网站中，使用autofac 容器， 并且使用 IObserver<in T> 作为通知的接收者，
如：`

public class WebsiteChangeObserver : IObserver<WebsiteChangeEvent>
{
    private readonly OrderProcessingService _orderProcessingService;

    public WebsiteChangeObserver(OrderProcessingService orderProcessingService)
    {
        this._orderProcessingService = orderProcessingService;
    }

    public void OnCompleted()
    {
    }

    public void OnError(Exception error)
    {
    }

    public void OnNext(WebsiteChangeEvent value)
    {
        // var _orderProcessingService = ServiceLocator.Current.GetInstance<OrderProcessingService>();

        var _orderProcessingService = IocManager.Instance.Container.Resolve<OrderProcessingService>();

        if (value.ChangeState == EntryState.Added)
        {
            var orderId = value.OrigEntity.OrderId;

            _orderProcessingService.MarkOrderAsDeployed(orderId);
        }
    }
}   `  

在网站启动的时候， 抛出一个错误：

No scope with a Tag matching 'AutofacWebRequest' is visible from the scope in which the instance was requested. This generally indicates that a component registered as per-HTTP request is being requested by a SingleInstance() component (or a similar scenario.) Under the web integration always request dependencies from the DependencyResolver.Current or ILifetimeScopeProvider.RequestLifetime, never from the container itself.

在 autofac 的 文档上 找到如下说明。 http://docs.autofac.org/en/la...

For application startup code or background threads, you may need to look at a different service locator mechanism like Common Service Locator to bypass the need for per-request scope

怎么解决这个问题呢？