Tracing is an
easy way to find out what is going on in your program. Back in the
days of classic ASP, the only way to trace what was happening in your
code was to insert
Response.Write statements in
strategic places. This allowed you to see that you had reached a
known point in the code, and perhaps to display the value of some
variables. The big problem with this hand-tracing technique, aside
from the amount of work involved, was that you had to laboriously
remove or comment out all those statements before the program went
ASP.NET provides better ways of gathering the trace information. You can add tracing at the application level or at the page level. With application-level tracing, every page is traced, while with page-level tracing, you choose the pages to which to add tracing.
page-level tracing, modify the
Page directive at the top of the
.aspx page, by adding a
Trace attribute and setting its value to
true, as follows:
<%@ Page language="c#" Codebehind="WebForm1.aspx.cs" AutoEventWireup="false" Inherits="DebuggingApp.WebForm1" Trace="true" %>
When you view this page, there will now be tables at the bottom that contain a wealth of information about your web application. Select a book from the drop-down list and you will see something like Figure 7-2.
Figure 7-2. Trace results
The top section, labeled Request Details, shows basic ...