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Release Date: June 2003

Hands-On Lab

Lab Manual

DEV-HOL19: Introduction to ASP.NET caching,tracing and state management

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Release Date: June 2003

Please do not remove this manual from the lab

The lab manual will be available from CommNet

Information in this document is subject to change without notice. The example companies,organizations, products, people, and events depicted herein are fictitious. No association withany real company, organization, product, person or event is intended or should be inferred.Complying with all applicable copyright laws is the responsibility of the user. Without limiting therights under copyright, no part of this document may be reproduced, stored in or introduced intoa retrieval system, or transmitted in any form or by any means (electronic, mechanical,photocopying, recording, or otherwise), or for any purpose, without the express writtenpermission of Microsoft Corporation.

Microsoft may have patents, patent applications, trademarked, copyrights, or other intellectualproperty rights covering subject matter in this document. Except as expressly provided in anywritten license agreement from Microsoft, the furnishing of this document does not give you anylicense to these patents, trademarks, copyrights, or other intellectual property.

2003 Microsoft Corporation. All rights reserved.

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Other product and company names herein may be the trademarks of their respective owners.

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Contents

Exercise #1: ASP.NET Session State ...............................................................................................................4Exercise 2: ASP.NET Tracing............................................................................................................................5Exercise 3: ASP.NET Page Output Caching.....................................................................................................7

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This lab provides a simple introduction to some of the great new features of ASP.NET simplify webapplication development.

Estimated time to complete this lab: 45 minutes

ObjectivesAfter completing this lab, you will be able to:

Use ASP.NET caching in your Web applications

Use different state management options provided by ASP.NET

Use ASP.NET tracing to debug your applications

The solution for this lab is located in the following folders:

C:\HandsOnLabs\ASP.NET\VB

Exercises

Exercise 1: ASP.NET Session StateASP.NET introduces several new ways to store session state which allow you to build more robust andfault tolerant applications than ever before. This lab provides an overview of the three state managementoptions offered by ASP.NET.

Exercise 2: ASP.NET TracingASP.NET Tracing provides detailed information about what is happening behind the scenes when a webapplication executes. This lab provides an overview of how page tracing can be used to better understandand debug your application.

Exercise 3: ASP.NET Page Output CachingOutput caching can increase the performance of your application significantly as it reduces the need togenerate dynamic pages on the fly. ASP.NET Page Output Caching provides a powerful yet simple to usemethod to implementing caching in your applications. This lab will provide an overview of simple PageOutput caching in ASP.NET.

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Exercise #1: ASP.NET Session StateIn this exercise, you will create a new ASP.NET web application in Visual Studio .NET, and experiement

with some different session state configuration options, and learn about cookieless session state.

Part 1: Setting Up and Exploring Session State

Note: As you perform this task, you can ignore the Start page.

Click Start->Programs->Microsoft Visual Studio .NET->Microsoft Visual Studio .NET.

Click File->New->Project.

In the Project Types pane, click Visual Basic Projects.

In the Templates pane, click ASP.NET Web Application.

Type http://localhost/SessionStateVB in the Location field.

Click OK.

Navigate to the WebForm1.aspx file, right-click and select View Code

In the Page_Load function, type the following:

Response.Write(Last accessed + Session(lastAccess) +

)

Session(lastAccess) = DateTime.Now.ToLongTimeString()

Response.Write("Time is now " + Session("lastAccess")) Compile and run the application by pressing Ctrl+F5 (Note: Visual Studio .NET might take a few

moments to compile the application)

Visual Studio .NET will bring up a Web browser which points to your application on the local web server

Now refresh the page a few times by clicking Refresh in the Web browser. Wait a few secondsbetween each refresh. Note that the time of the last access is stored in the session state objectbetween refreshes.

Now lets see what happens to the session state information when the Web server is restarted. ClickStart->Run and type iisreset.

Click OK.

Now go back to the Web browser and click Refresh again. (Note: the page might take a few momentsto refresh this time).

Note that the Last accessed time is blank. We have lost our session data because of the Web serverreset.

Close the Web browser

Part 2: Using Out-Of-Process Session State

So far weve been using in-process session state, whereby session state data is stored in the sameprocess as ASP.NET (this is why we lost our session state when we reset the web server). We will nowstart experimenting with other settings.

In the SessionStateVB project we create in Part, 1 navigate to the Solution Explorer window (in thetop, right hand corner of Visual Studio .NET)

Open the file named web.config. This file contains all the configuration settings for our application.

Locate the tag

The value of the mode attribute is now InProc. Change this to StateServer as shown in the followingcode. This is the only change necessary to ensure that session state is not lost when the web server isrestarted.

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Before testing, you need to start the ASP.NET State Service (which will store the session state data).Click Start->Run and type net start ASPNET_STATE.

Press Ctrl+F5 to compile and run the page.

Refresh the page a few times by clicking Refresh in the Web browser. Wait a few seconds betweeneach refresh. Note that the time of the last access is stored in the session state object betweenrefreshes.

Restart the web server. Click Start->Run and type iisreset.

Click OK.

Now go back to the Web browser and click Refresh again.

Note that the Last accessed time is still available. We have no lost our session state data.

Close the Web browser

Note 1: If you wish to share state between different web servers (in a web farm scenario for instance), you canrun the ASP.NET State Service on a remote machine. Your application can be directed to this remotemachine using the StateConnectionString attribute of the tag in web.config. Simplyset the value ofStateConnectionString to the IP address of the machine running the ASP.NET State

Service.Note 2: You may also store state information in a SQLServer database. To do this change the mode attribute

of the tag to SQLServer.

Part 3: Using Cookieless Session State

In web.config, change the mode attribute of the tag back to InProc.

Now change the cookieless attribute of the tag to true. This attribute controlswhether cookies should be sent to the client when a session is initiated. If this attribute is set to true,ASP.NET will not user cookies. Instead, the session id is sent as part of the URL.

Your tag should now look like the following:

Press Ctrl+F5 to compile and run the application

Note that the URL of your application gets modified to include the session id, looking something like thefollowing:

http://localhost/SessionStateVB/(hgyyz5vjzxztxv55h4cai045)/WebForm1.aspx

Close the web browser

Note; You may be asking when cookieless sessions are applicable. One case is when a corporate policyprevent usage of cookies, any Intranet applications then need to use a different way to associate a clientwith data on the server. There are alternatives to using session data, e.g. hidden fields containing data,but nothing is as easy to use as normal session data.

Exercise 2: ASP.NET TracingIn this exercise you will add tracing data to the application built in Exercise 1. Youll learn how a single line

of code will enable us to see whats really happening behind the scenes in our application.

Part 1: Getting Started

Navigate to the SessionStateVB project which you used in Exercise 1.

Make sure that the tag in the web.config file is identical to the following:

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Locate the tag in the web.config file.

Enable ASP.NET tracing by changing the enabled attribute to true. Also change the pageOutputattribute to true. The tag should now look like the following:

Press Ctrl+F5 to run the application and observe the result.

Note:

The attributes available for the tag are:

enabled: Set to true | false, indicates whether Tracing is enabled for the application (default is false).

pageOutput: Set to true | false, indicates whether trace information should be rendered at the end ofeach page - or only accessible via the trace.axd utility (default is false).

requestLimit: Number of trace requests to store on the server (default is 10).

traceMode: Set to SortByTime | SortByCategory, indicates the display order for Trace messages(default is SortByTime).

localOnly: Set to true | false, indicates whether Tracing is enabled for localhost users or for all users(default is true).

At the top your page will be displayed. Below your page is a number of informational elements that is

useful for understanding how the page was created and which settings were available at the time.

The information listed are, in order:

Request Details

Trace Information: Trace of event that happens during page rendering. Later we will see how you canwrite information here yourself.

Control Tree

Session State (list all session variables)

Cookie Collection

Header Collection

Server Variables

After having looked at the basic trace information lets insert some trace statements of your own. TheTrace class statement comes in two flavors: Write and Warn. They both take the same arguments. Theonly difference between them is the color they trace in, Write uses black and Warn uses red.

Part 2: Inserting Statements into the Page Trace


In the Page_Load function, type the following below the code you entered in Exercise 1:

Trace.Write("This is a Trace.Write message")

Trace.Warn("This is a Trace.Warn message")

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Press Ctrl+F5 to compile the application. Observe the resulting trace information on the page. Eachevent is shown as well as the execution time between each event.

Close the web browser.

Note: ASP.NET introduces an event-based programming model to web development. MSDN(msdn.microsoft.com) contains many helpful articles which explain this model in detail and how to takeadvantage of this model in your applications.

Part 3: Using trace.axd

Another way to view the trace information is to use the special page trace.axd. This page provides asummary of recent traces and allows you to click on one of them to see the same details you have justseen above. With this approach only the trace information itself is displayed, the page is not renderedabove it.

Press Ctrl+F5 to compile and run your application.

Access the trace.axd file for your application by entering the following URL in the web browser:http://localhost/SessionStateVB/trace.axd

You should now see a series of application traces from the past few requests to you application.


Exercise 3: ASP.NET Page Output CachingPart 1: Simple Output Caching

Note: As you perform this task, you can ignore the Start page.

Close Visual Studio .NET if it it open. Do not save any change to existing projects.

Click Start->Programs->Microsoft Visual Studio .NET->Microsoft Visual Studio .NET.

Click File->New->Project.

In the Project Types pane, click Visual Basic Projects.

In the Templates pane, click ASP.NET Web Application.

Type http://localhost/OutputCachingVB in the Location field.

Click OK.


Enter the following code in the Page_Load function:

Response.Write(This page was created on: + DateTime.Now.ToLongTimeString())

Press Ctrl+F5 to run the project.

Refresh the page several times to see that the page creation time is updated each time you refresh.


Navigate to the WebForm1.aspx file.

Right click on the WebForm1.aspx design surface and select View HTML Source

At the top of the page, enter the following code:

Press Ctrl+F5 to run the project.

Refresh the page several times. Note that the page is now only updated every 10 seconds. The page isbeign compiled once every ten seconds and place in the cache. Subsequent requests for this page arebeing served from the cache.

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This is the simplest for of caching. As many pages have slightly different contents depending on asimple parameter in the query string this simple form of caching can be extended. You will now utilizethe VaryByParam argument in the OutputCache directive above.

Part 2: Caching depending on a parameter

We will now modify the OutputCache directive to vary by something, and cache the page for a longertime. Right click on WebForm1.aspx and select View Code

Add the following to the Page_Load function above the code you entered in part 1

Response.Write(Request.QueryString.Item("something"))

Response.Write("

")

Navigate back to WebForm1.aspx. Right-click and select View HTML Source

Modify the OutputCache directive to look like the following:

You have just created a page that cache a version of itself depending on the value of a query stringparameter called fruit. Each version of this page writes out the value of fruit to help you keep track ofthe version.

Press Ctrl+F5 to run the application. Try calling passing different parameters to the application by entering the following URLs in the web

browser:

http://localhost/OutputCachingVB/WebForm1.aspx?fruit=Apple

http://localhost/OutputCachingVB/WebForm1.aspx?fruit=Pear

http://localhost/OutputCachingVB/WebForm1.aspx?fruit=Orange

Note that the page is only updated when you enter a new value for the fruit parameter. There is anindependent cached version of the page in memory for each value of fruit you submit. All of thesepages are recompiled every 30 seconds (as we requested in the OutputCache directive).

Note: ASP.NET provides several very flexbile and easy to use caching options which makes it much simplerfor you to build high performance applications. We did not highlight it here, but ASP.NET also allowsyou to cache fragments of pages, instead of the entire page. For more information on page fragmentcaching please refer to the PAG lab series (also on this machine) or MSDN (msdn.microsoft.com).

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