Syntax and Semantics

• Request(): ASP returns an array of strings; ASP.NET returns a string.
• Request.QueryString(): ASP returns an array of strings; ASP.NET returns a string.
• Request.Form(): ASP returns an array of strings; ASP.NET returns a string.

In ASP, the Request, Request.QueryString, and Request.Form collections return string arrays from lookups. For example, in traditional ASP the query string values from a request to http://localhost/test/Test.asp?values=45&values=600 would be accessed as follows:

<%
    ' Below line outputs: "45, 600"
    Response.Write Request.QueryString("values")

    ' Below line outputs: "45"
    Response.Write Request.QueryString("values")(1)
%>

In ASP.NET, these collections require an explicit method to get array access. These arrays are also now 0-index based. For example, in ASP.NET the query string values from a request to http://localhost/test/Test.aspx?values=45&values=600 would be accessed as follows:

<%
    ' Below line outputs: "45, 600"
    Response.Write(Request.QueryString("values"))

    ' Below line outputs: "45"
    Response.Write(Request.QueryString.GetValues("values")(0))
%>

These arrays are most commonly used when form values are posted from multiselect list boxes (<select multiple>) or when multiple check boxes have the same name.

Semantic Differences Between ASP.NET and ASP

• ASP.NET pages only support a single language.

  ASP allowed multiple languages to be used on a single page, which was useful for script library scenarios. Because of ASP.NET's compiled nature, it supports only a single language on a page. However, it is still possible to have multiple pages, each with a separate language, within a single application. User Controls might also have a different language from the page that contains them. This enables you to integrate functionality written in different languages in a single page. This is an adequate substitute for the multiple-language Include files that are prevalent in traditional ASP applications.

• ASP.NET page functions must be declared in <script runat=server> blocks.

  In ASP, page functions could be declared within <% %> blocks:

  <%
      Sub DoSomething()
          Response.Write "Hello World!"
      End Sub
  
      DoSomething
  %>
  

  In ASP.NET, page functions must be declared in <script runat=server> blocks:

  <script language="VB" runat=server> Sub DoSomething() Response.Write ("Hello World!") End Sub </script> <% DoSomething() %> VB

• ASP.NET does not support page-render functions.

  In ASP, page-render functions could be declared with <% %> blocks:

  <% Sub RenderSomething() %>
         <font color="red"> Here is the time: <%=Now %> </font>
  <% End Sub %>
  
  <%
     RenderSomething
     RenderSomething
  %>
  

  In ASP.NET, this must be rewritten:

  <script language="VB" runat=server> Sub RenderSomething() Response.Write("<font color=red> ") Response.Write("Here is the time: " & Now) End Sub </script> <% RenderSomething() RenderSomething() %> VB

Section Summary

1. With three exceptions, ASP.NET is 100% API-compatible with traditional ASP. The API changes are that, now, Request(), Request.QueryString(), and Request.Form() all return individual strings, rather than string arrays.
2. ASP.NET pages support only a single language.
3. ASP.NET page functions must be declared in <script runat=server> blocks.
4. Page-render functions are not supported.