Page 119 - DCAP312_WEB_TECHNOLOGIES_II

Unit 6: Error Handling

Under the top level information is the Trace log, which provides details of page life cycle. It Notes
provides elapsed time in seconds since the page was initialized.(See Figure 6.1)

Figure 6.1: Trace Information

Trace Information
Category
aspx.page Begin PreInit
aspx.page End PreInit
aspx.page Begin Init
aspx.page End Init
aspx.page Begin InitComplete
aspx.page End InitComplet
aspx.page Begin LoadState
aspx.page End LoadState
aspx.page Begin ProcessPostData
aspx.page End ProcessPostData
aspx.page Begin PreLoad
aspx.page End PreLoad
aspx.page Begin Load
aspx.page End Load
aspx.page Begin ProcessPostData Second Try
aspx.page End ProsessPostData Second Try
aspx.page Begin Raise ChangedEvents
aspx.page End Raise ChangedEvents

The control tree, which lists all controls on the page in a hierarchical manner:

Figure 6.2: Control tree

Control Tree
Control UniqueID Type Render size
__Page ASP.default_aspx 2850
ctl02 System.Web.UI.LiteralControl 175
ctl00 System.Web.UI.HtmlControls.HtmlHead 70
ctl01 System.Web.UI.HtmlControls.HtmlTitle 57
ctl03 System.Web.UI.LiteralControl 14
form1 System.Web.UI.HtmlControls.HtmlForm 2571
ctl04 System.Web.UI.LiteralControl 27
lblheading System.Web.UI.WebControl.Label 65
ctl05 System.Web.UI.LiteralControl 42
ddlquotes System.Web.UI.WebControl.DropDownlist 570
ctl06 System.Web.UI.LiteralControl 42
lblquotes System.Web.UI.WebControl.Label 96
ctl07 System.Web.UI.LiteralControl 42
HyperLink1 System.Web.UI.WebControl.HyperLink 49
ctl08 System.Web.UI.LiteralControl 24
ctl09 System.Web.UI.LiteralControl 20

Last in the Session and Application state summaries, cookies and headers collections, followed
by list of all server variables.
The Trace object allows you to add custom information to the trace output. It has two methods
to accomplish this: the Write method and the Warn method.
Change the Page_Load event handler to check the Write method:

protected void Page_Load(object sender, EventArgs e)
{
Trace.Write( “Page Load”);
if (!IsPostBack)
{
Trace.Write( “Not Post Back, Page Load”);
string[,] quotes

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