Trace

1.System.Web.Context.Trace
http://www.jb51.net/article/1303.htm

Page:

<%@ Page Language="C#"  Trace="true" %>
Web.Congig:

<trace enabled="true" mostRecent="true" traceMode="SortByTime" requestLimit="10000" localOnly="false" pageOutput ="true"/>

2.System.Diagnostics.Trace
http://www.haogongju.net/art/1018237

System.Diagnostics.Trace.Assert(false, "Hello");
http://wenwen.soso.com/z/q114732761.htm