/// <summary>
/// Begin sub-service extending request.
/// </summary>
/// <param name="service">sub-service</param>
protected override IAsyncResult SubServiceBeginRequest(IKsiService service)
{
return(_publicationTime.HasValue ? service.BeginExtend(_aggregationTime, _publicationTime.Value, null, null) : service.BeginExtend(_aggregationTime, null, null));
}