Module 5: Using Trace in ASP.NET Pages

Contents Overview 1 Overview of Tracing 2 Trace Information 3 Page-Level Trace 4 Application-Level Trace 9 Lab 5: Adding Trace to an ASP.NET Page 14 Review 15 Module 5: Using Trace in ASP.NET Pages BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Information in this document is subject to change without notice. The names of companies, products, people, characters, and/or data mentioned herein are fictitious and are in no way intended to represent any real individual, company, product, or event, unless otherwise noted. Complying with all applicable copyright laws is the responsibility of the user. No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, for any purpose, without the express written permission of Microsoft Corporation. If, however, your only means of access is electronic, permission to print one copy is hereby granted. Microsoft may have patents, patent applications, trademarks, copyrights, or other intellectual property rights covering subject matter in this document. Except as expressly provided in any written license agreement from Microsoft, the furnishing of this document does not give you any license to these patents, trademarks, copyrights, or other intellectual property.  2001 Microsoft Corporation. All rights reserved. Microsoft, BackOffice, MS-DOS, Windows, Windows NT, <plus other appropriate product names or titles. The publications specialist replaces this example list with the list of trademarks provided by the copy editor. Microsoft is listed first, followed by all other Microsoft trademarks in alphabetical order. > are either registered trademarks or trademarks of Microsoft Corporation in the U.S.A. and/or other countries. <The publications specialist inserts mention of specific, contractually obligated to, third-party trademarks, provided by the copy editor> Other product and company names mentioned herein may be the trademarks of their respective owners. Module 5: Using Trace in ASP.NET Pages iii BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Instructor Notes This module describes the trace feature of ASP.NET. Students will learn about the two tracing techniques in ASP.NET, page-level tracing and application- level tracing. In the lab, students will enable and disable tracing for an ASP.NET page. They will also add custom trace messages to an ASP.NET page and a middle-tier component. After completing this module, students will be able to: Describe page-level and application-level tracing. Enable and disable tracing for an ASP.NET page. Add custom trace information. Materials and Preparation This section provides the materials and preparation tasks that you need to teach this module. Required Materials To teach this module, you need the following materials: ! Microsoft ® PowerPoint ® file 2063A_05.ppt ! Module 5, “Using Trace in ASP.NET Pages” (2063A_05.doc) ! Lab, “Adding trace to an ASP.NET Page” (2063A_L05.doc) Preparation Tasks To prepare for this module, you should: ! Read all of the materials for this module. ! Complete all the demonstrations. ! Complete the lab. Presentation: 60 Minutes Lab: 30 Minutes iv Module 5: Using Trace in ASP.NET Pages BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Module Strategy Use the following strategy to present this module: ! Overview of Tracing Start the module with an overview of tracing and why do we need to enable trace on an application page. ! Trace Information This section described the type of information that can be retrieved by enabling trace on a page. When teaching this, point to each category in the illustration and discuss it briefly. ! Page-Level Trace Page-level Tracing provides the ability to write debugging statements directly to the output of a page, and conditionally execute debugging code when tracing is enabled. This section describes how page-level tracing works. This section ends with a topic on how to trace into a component. When talking about tracing into a component, tell them about why it is useful to be able to trace into a component. ! Application-Level Trace ASP.NET also provides a way to enable tracing for the entire application and not just a single page. This section describes how application-level trace works. Module 5: Using Trace in ASP.NET Pages 1 BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Overview ! Overview of Tracing ! Trace Information ! Page-Level Trace ! Application-Level Trace In earlier versions of ASP, tracing of code was accomplished by inserting Response.Write statements, wherever required. One main drawback of this technique was the removal of the excess code added when the application is deployed, and thus the inability to use the output from the Response.Write statements in a production environment. ASP.NET overcomes such drawbacks by introducing an automatic tracing mechanism. This tracing mechanism can be enabled and disabled either on a page-by-page basis, or for an entire application, and can be configured in the config.web file. After completing this module, you will be able to: ! Describe page-level and application-level tracing. ! Enable and disable tracing for an ASP.NET page. ! Add custom trace information. <<add something on Debug object and conditional compilation. Trace is good because you can turn it on from config.web in a production environment to see what's going wrong. It can also output to a log file in a production environment>> Topic Objective To provide an overview of the module topics and objectives. Lead-in In this module, you will learn how to use the trace feature of ASP.NET. 2 Module 5: Using Trace in ASP.NET Pages BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Overview of Tracing ! With Tracing You Can: # Output Variables or Structures # Assert Whether a Condition is Met # Trace through the Execution Path of the Application ! Can Be Enabled and Disabled, Either on a Page-By-Page Basis, or for an Entire Application The tracing feature enables you to insert debugging print statements into your code to output variables or structures, assert whether a condition is met, or just generally trace through the execution path of the application. All this information is outputted with a page or saved to a log. Topic Objective To describe tracing. Lead-in Tracing enables you to see the execution path and output variable values from your application. Module 5: Using Trace in ASP.NET Pages 3 BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Trace Information Tracing provides a lot of information to the developer of an ASP.NET application. The trace output screen contains the following categories of information. Category Description Request Details Information about the request: session ID, time of request, type of request, and the status. Trace Information Output from standard and custom trace statements. Control Tree List of all items on the page Cookies Collection List of Cookies being used. Headers Collection List of items in the HTTP header. Form Collection List of controls and their values on the form being posted. Server Variables List of all server variables and their values. Topic Objective To list the information provided in a trace output. Lead-in The trace output page provides lots of information. 4 Module 5: Using Trace in ASP.NET Pages BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY $ Page-Level Trace ! How Does Page-Level Trace Work? ! Demonstration: Adding Page-Level Trace Statements ! Tracing into a Component Page-level tracing provides the ability to write debugging statements directly to the output of a page, and conditionally execute debugging code when tracing is enabled. The performance data and the developer-specified messages (if any) are injected into the HTML output stream to the client to help clarify precisely what occurs when the framework processes a page request. In this section, you will learn how page-level tracing works. Topic Objective To describe how page-level tracing works. Lead-in ASP.NET aids the debugging and testing process by providing two types of trace capabilities, page-level and application- level. Module 5: Using Trace in ASP.NET Pages 5 BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY How Does Page-Level Trace Work? ! Enabling Tracing for a Page ! Inserting Trace Messages ! Sort Output by Category <%@ Page Language="VB" Trace="true"%> <%@ Page Language="VB" Trace="true"%> Trace.Write("category", "message") Trace.Write("category", "message") <%@ Page Language="VB" Trace="true" TraceMode="SortByCategory"%> <%@ Page Language="VB" Trace="true" TraceMode="SortByCategory"%> The page-level trace mechanism performs two functions when it is enabled: ! It automatically appends a table of performance data to the end of the page. ! It allows developers to insert custom diagnostic messages throughout their code. Let’s look at how a page-level trace works. Enabling Tracing for a Page The trace capability must be enabled prior to use. To enable tracing for a page, include the following directive at the top of the page code. <%@ Page Language="VB" Trace="true" %> The page exposes the Trace property of the type TraceContext, which can be used to output debugging statements to the page output. The default value of the Trace attribute is set to false. Inserting and Organizing Trace Messages You can use the Trace object to write debugging statements There are two methods you can use to insert custom messages: Trace.Write and Trace.Warn. Trace.Write is used to display messages, and Trace.Warn is used to display warnings. Trace.Write and Trace.Warn are easy to distinguish because Trace.Warn uses a red font color in its output. In their simplest forms, each method takes two string arguments: public void Write( string category, string message ) public void Warn( string category, string message ) Topic Objective To explain how page-level tracing works. Lead-in Let’s look at how page-level trace works. 6 Module 5: Using Trace in ASP.NET Pages BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY The category argument is used to organize messages. For example: Trace.Write("Custom Trace","Beginning User Code .") Trace.Warn("Custom Trace","Array count is null!") Often you will need to execute additional code to construct the statements to pass to the Trace.Write or Trace.Warn methods, where the code should only execute if tracing is enabled for the page. To support this, the page exposes a boolean property, Trace.IsEnabled, that returns TRUE only if tracing is enabled for the page. You should check Trace.IsEnabled first to guarantee your debugging code will only execute when tracing is enabled. If Trace.IsEnabled strTrace = "create a trace string here" End If Trace.Write(strTrace) Sorting Trace Messages The TraceContext class contains the TraceMode property that defines how trace messages are sorted in the page output. <%@ Page Trace="true" TraceMode="SortByCategory" %> TraceMode is of the type TraceModeEnum, and has two possible values: ! SortByTime Trace messages are outputted in order of chronological occurrence. This is the default setting. ! SortByCategory Trace messages are sorted alphabetically by the category argument to the Trace.Write and Trace.Warn methods. [...]... TRAINER PREPARATION PURPOSES ONLY 14 Module 5: Using Trace in ASP.NET Pages Lab 5: Adding Trace to an ASP.NET Page Topic Objective To introduce the lab Lead -in In this lab, you will enable and disable tracing for an ASP.NET page You will also add custom trace messages to an ASP.NET page and a middle-tier component BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Module 5: Using. .. virtual root of IIS In this section, you will learn how an application-level trace works BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY 10 Module 5: Using Trace in ASP.NET Pages How Does Application-Level Trace Work? Topic Objective To explain how applicationlevel trace works Lead -in In addition to exposing a generalized trace facility to developers, the ASP.NET runtime can... PURPOSES ONLY 8 Module 5: Using Trace in ASP.NET Pages Tracing into a Component Topic Objective To show how to trace into a component Lead -in If you have a component that is called from an ASP.NET page, you can add trace statements to the methods of the component too ! Import the System.Web Library Imports System.Web Imports System.Web ! Enable Tracing in Class Constructor HttpContext.Current .Trace. IsEnabled... tracing Lead -in In this demonstration, you will see how to use trace at the application level In this demonstration, you will see how to use trace at the application level BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Module 5: Using Trace in ASP.NET Pages 13 Delivery Tip 1 Create a new file named config.web in the \Inetpub\wwwroot\2063 folder 2 Enable application-level tracing... System.Web 2 In the constructor of the class where you want to add trace statements, enable tracing with the following statement: HttpContext.Current .Trace. IsEnabled = True 3 Then, in the method, use the following: HttpContext.Current .Trace. Write _ ("component", "this is my trace statement") BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Module 5: Using Trace in ASP.NET Pages 9... Module 5: Using Trace in ASP.NET Pages 15 Review Topic Objective To reinforce module objectives by reviewing key points Lead -in The review questions cover some of the key concepts taught in the module ! Describe Page-Level and Application-Level Tracing ! Enable and Disable Tracing for an ASP.NET Page ! Add Custom Trace Information 1 How do you enable page-level tracing? To enable page-level trace, you set.. .Module 5: Using Trace in ASP.NET Pages 7 Demonstration: Adding Page-Level Trace Statements Topic Objective To demonstrate page-level and application-level tracing Lead -in In this demonstration, you will see how to use tracing at the page level In this demonstration, you will see how to use trace at the page level Delivery Tip 1 Open the file storedprocedure.aspx in 2063\DemoCode\Mod05... requests, and prevents trace statements from being output to the requesting browser BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY 12 Module 5: Using Trace in ASP.NET Pages Demonstration: Adding Application-Level Trace Statements Statements Topic Objective To... page trace. axd in the application's root folder For example, if the URL to your application were http://localhost/myapplication, you would view the file http://localhost/myapplication /trace. axd to access the trace statistics for that application BETA MATERIALS FOR MICROSOFT CERTIFIED TRAINER PREPARATION PURPOSES ONLY Module 5: Using Trace in ASP.NET Pages 11 Setting Trace Attributes The trace section... Application-Level Trace Topic Objective To introduce the topics in this section Lead -in In this section, you will learn about application-level trace ! How Does Application-Level Trace Work? ! Demonstration: Adding Application-Level Trace Statements ASP.NET also provides a way to enable tracing for the entire application and not just a single page An ASP.NET application is the collection of files and folders in a . Tracing 2 Trace Information 3 Page-Level Trace 4 Application-Level Trace 9 Lab 5: Adding Trace to an ASP. NET Page 14 Review 15 Module 5: Using Trace in ASP. NET. numberbox.aspx. 7. Add some trace messages to both add.aspx and numberbox.aspx. 8. View add.aspx in Internet Explorer. 8 Module 5: Using Trace in ASP. NET Pages