In People.aspx 

 ===========================

 <asp:ObjectDataSource ID="ObjectDataSource1" runat="server" SelectMethod="GetAllPersons"
                TypeName="People"></asp:ObjectDataSource>

============================ 

in Class: People: 

============================ 

  public static class People {

    private static bool _isInitialized = false;
    private static PeopleProvider _provider;
    private static SmallBusinessDataProvidersSection _providersSection;

    public static PeopleProvider Provider {
      get {
        Initialize();
        return _provider;
      }
    }

    public static List<Person> GetAllPersons()
    {
        return Provider.GetAllPersons();
    }

 =========================

There are two GetAllPersons functions in: SqlPeopleProvider.cs and XmlPeopleProvider.cs, how the program knows go to which one? at the moment, it will use the function in: XmlPeopleProvider.cs, it must have some relationship with: Initialize(), but can you tell me how?

Thanks

JT