I have an existing asp.net web application I am redesigning to use a service architecture. I have the beginnings of an WCF service which I am able to call and perform functions with no problems. As far as updating data, it all makes sense. For example, I have a button that says Submit Order, it sends the data to the service, which does the processing.

Here's my concern: If I have an ASP.NET page that shows me a list of orders (View Orders page), and at the top I have a bunch of drop down lists for order types, and other search criteria which is populated by querying different tables from the database (lookup tables, etc). I am hoping to eventually completely decouple the web application from the DB, and use data contracts to pass information between the BLL, the SOA, and the web app. With that said, how can I reduce the # of WCF calls needed to load my "View Orders" page? I would need to make 1 call get the list of orders, and 1 call for each drop down list, etc because those are populated by individual functions in my BLL.

Is it good architecture to create a web service method that returns back a specialized data contract that consists of everything you would need to display a View Orders page, in 1 shot? Something like this pseudocode:

public class ViewOrderPageDTO
{
  public OrderDTO[] Orders { get; set; }
  public OrderTypesDTO[] OrderTypes { get; set; }
  public OrderStatusesDTO[] OrderStatuses { get; set; }
  public CustomerListDTO[] CustomerList { get; set; }
}

Or is it better practice in the page_load event to make 5 or 6 or even 15 individual calls to the SOA to get the data needed to load the page? Therefore, bypassing the need for specialized wcf methods or DTO's that conglomerate other DTO?

Thanks for your input and suggestions.