Answers for Day 17 | Sams Teach Yourself ASP.NET in 21 Days (2nd Edition)


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	Sams Teach Yourself ASP.NET in 21 Days, Second Edition By Chris Payne
	Table of Contents

	Appendix A. Answers to Quiz Questions

Quiz

1:	What is a proxy class?
A1:	A class that provides methods for a client application to access a Web Service's methods. You use the proxy class because it provides built-in support for sending and receiving XML messages.
2:	Write an example of a typical use of the `disco.exe` tool.
A1:	disco http://localhost/tyaspnet21days/services.disco
3:	Write an example of a typical use of the `wsdl.exe` tool.
A1:	wsdl /language:VB http://localhost/tyaspnet21days/day16/Calculator.asmx?WSDL
4:	True or false: Discovery must be performed before proxy generation.
A1:	False. Discovery isn't a necessary step.
5:	Which two namespaces are required for using SOAP headers to access services?
A1:	`System.Web.Services` and `System.Web.Services.Protocols`.
6:	Create a simple SOAP header class. What do you do with this class in a Web method? On the client?
A1:	1: Public Class SOAPHeader : Inherits SoapHeader 2: Public Username as string 3: Public Password as string 4: End Class You need to create an instance of this class in any class that you want to expose as a service. The Web methods that use this class must specify the attribute `<SoapHeader()>`. The client must create an instance of the class as well (through the proxy), and set its properties.

Exercise

Q1:

Generate a proxy class for the ConvertUnits service you created in exercise 2 on Day 16. Build an interface to allow users to enter values.

A1:

First create a proxy with the following command:

 wsdl /l:VB /namespace:TYASPNET.Clients http://localhost/tyaspnet21days/day16/ConvertUnits.asmx?WSDL

Compile the proxy with the following command:

 vbc /t:library /out:..\..\bin\TYASPNET.Clients.ConvertUnits.dll /r:System.dll /r:System.Data.dll /r:System.Web.dll /r:System.Web.Services.dll /r:System.Xml.dll ConvertUnits.vb

Then build the ASP.NET page:

 1:    <%@ Page Language="VB" %> 2: 3:    <script runat="server"> 4:       sub Submit(Sender as Object, e as EventArgs) 5:          dim objService as new TYASPNET.Clients.ConvertUnits 6:          dim dblResult as double 7: 8:          dblResult = objService.Convert(tbValue.Text, _ 9:             lbUnitsFrom.SelectedItem.Text, _ 10:             lbUnitsTo.SelectedItem.Text) 11: 12:          lblMessage.Text = tbValue.Text & " " & _ 13:             lbUnitsFrom.SelectedItem.Text & " = " & _ 14:             dblResult & " " & lbUnitsTo.SelectedItem.Text 15:       end sub 16:    </script> 17: 18:    <html><body> 19:       <form runat="server"> 20:          Convert: 21:          <asp:TextBox  runat="server" /> 22:          <asp:ListBox  runat="server" 23:             Size="1"> 24:             <asp:ListItem>mm</asp:ListItem> 25:             <asp:ListItem>cm</asp:ListItem> 26:             <asp:ListItem>m</asp:ListItem> 27:             <asp:ListItem>km</asp:ListItem> 28:             <asp:ListItem>in</asp:ListItem> 29:             <asp:ListItem>ft</asp:ListItem> 30:             <asp:ListItem>yd</asp:ListItem> 31:             <asp:ListItem>mi</asp:ListItem> 32:          </asp:ListBox> 33:          to: 34:          <asp:ListBox  runat="server" 35:             Size="1"> 36:             <asp:ListItem>mm</asp:ListItem> 37:             <asp:ListItem>cm</asp:ListItem> 38:             <asp:ListItem>m</asp:ListItem> 39:             <asp:ListItem>km</asp:ListItem> 40:             <asp:ListItem>in</asp:ListItem> 41:             <asp:ListItem>ft</asp:ListItem> 42:             <asp:ListItem>yd</asp:ListItem> 43:             <asp:ListItem>mi</asp:ListItem> 44:          </asp:ListBox><p> 45: 46:          <asp:Button  runat="server" 47:             Text="Submit" 48:             OnClick="Submit" /><p> 49:          <asp:Label  runat="server" /> 50:       </form> 51:    </body></html>


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