You create the following WCF Data Service:

public class Northwind : DataService<NorthwindEntities>
{
...
[WebGet]
public IQueryable<Order> GetOrdersByCity(string city)
{
...
}
}

You need to retrieve the entities returned by the GetOrdersByCity service operation for the city Redmond.

Which URI should you use?

To retrieve the entities returned by the GetOrdersByCity service operation for the city Redmond, specify the GetOrdersByCity service operation name as a relative path and specify city='Redmond' as a query string parameter.

The URI http://localhost:12345/Northwind.svc/GetOrdersByCity('Redmond') is incorrect. Service operation parameters must be given as query string parameters.