Building Microsoft ASP.NET Application for mobile Devices

Building Microsoft ASP.NET Applications for Mobile

Devices, Second Edition

by Andy Wigley and Peter Roxburgh ISBN:073561914X

Microsoft Press © 2003 (694 pages)

This book shows programmers how to use the Microsoft .NET

Framework, ASP.NET, and Microsoft Visual Studio .NET 2003

to create powerful, next generation applications that are

available anywhere--on phones, Pocket PCs, and other mobile

devices.

Companion Web Site

Table of Contents

Building Microsoft ASP.NET Applications for Mobile Devices, Second Edition

Introduction

Chapter 1 - Introducing Microsoft ASP.NET for the Mobile Web

Chapter 2 - Getting Started

Chapter 3 - Programming ASP.NET Mobile Web Forms

Chapter 4 - Programming the Standard Controls

Chapter 5 - Special-Purpose Controls and Validation Controls

Chapter 6 - Programming the List Controls

Chapter 7 - Using the Downloadable Controls

Chapter 8 - Programming Styles and Style Sheets

Chapter 9 - Customizing with Property Overrides and Templates

Chapter 10 - Advanced List Control Programming

Chapter 11 - Accessing Data

Chapter 12 - State Management

Chapter 13 - Enhancing Application Performance

Chapter 14 - Multilingual and Multicultural Web Applications

Chapter 15 - XML Web Services

Chapter 16 - Debugging, Testing with Emulators, and Handling Run-Time Errors

Chapter 17 - Packaging and Configuration

Chapter 18 - ASP.NET Application Security

Chapter 19 - Supporting New Clients

Chapter 20 - Building a Reusable User Interface as User Controls

Chapter 21 - Creating Custom Controls by Inheritance and Composition

Chapter 22 - Programming Device Adapters and Building Controls from Scratch

Index

List of Figures

List of Tables

List of Listings

List of Sidebars

Building Microsoft ASP.NET Applications for Mobile

Devices, Second Edition

by Andy Wigley and Peter Roxburgh ISBN:073561914X

Microsoft Press © 2003 (694 pages)

This book shows programmers how to use the Microsoft .NET

Framework, ASP.NET, and Microsoft Visual Studio .NET 2003

to create powerful, next generation applications that are

available anywhere--on phones, Pocket PCs, and other mobile

devices.

Companion Web Site

Table of Contents

Building Microsoft ASP.NET Applications for Mobile Devices, Second Edition

Introduction

Chapter 1 - Introducing Microsoft ASP.NET for the Mobile Web

Chapter 2 - Getting Started

Chapter 3 - Programming ASP.NET Mobile Web Forms

Chapter 4 - Programming the Standard Controls

Chapter 5 - Special-Purpose Controls and Validation Controls

Chapter 6 - Programming the List Controls

Chapter 7 - Using the Downloadable Controls

Chapter 8 - Programming Styles and Style Sheets

Chapter 9 - Customizing with Property Overrides and Templates

Chapter 10 - Advanced List Control Programming

Chapter 11 - Accessing Data

Chapter 12 - State Management

Chapter 13 - Enhancing Application Performance

Chapter 14 - Multilingual and Multicultural Web Applications

Chapter 15 - XML Web Services

Chapter 16 - Debugging, Testing with Emulators, and Handling Run-Time Errors

Chapter 17 - Packaging and Configuration

Chapter 18 - ASP.NET Application Security

Chapter 19 - Supporting New Clients

Chapter 20 - Building a Reusable User Interface as User Controls

Chapter 21 - Creating Custom Controls by Inheritance and Composition

Chapter 22 - Programming Device Adapters and Building Controls from Scratch

Index

List of Figures

List of Tables

List of Listings

List of Sidebars

Back Cover

Extend your programming expertise across the widest range of mobile devices with this incisive guide to Microsoft

ASP.NET mobile controls. Now integrated into Microsoft Visual Studio .NET 2003, ASP.NET mobile controls enable you

to build applications that render intelligently on different devices—regardless of markup language, browser, or form

factor. The authors expertly guide you through the mobile Web application development process, explaining how to

fully exploit Visual Studio .NET and the Microsoft .NET Framework 1.1 for rapid and more flexible development.

Discover how to create innovative, intuitive solutions—instead of wrestling with interoperability issues.

Learn how to:

Build mobile Web Forms pages with device-independent properties, methods, and events

Use “code-behind” techniques to separate programming logic from the UI

Employ the standard controls or download new custom controls

Build controls from scratch and program device adapters

Customize applications for specific devices with templates

Access data using Microsoft ADO.NET and the Visual Database Tools

Know when to use application vs. session state

Apply best practices for using XML Web services in mobile applications

Help secure applications with ASP.NET authentication services

Develop multilingual and multicultural applications

Debug code, trap runtime errors, and use software emulators to test applications

Configure, package, and deploy applications

About the Authors

As a principal technologist at Content Master Ltd., a technical-authoring company based in the United Kingdom, Andy

Wigley focuses on the use of .NET in mobility applications. A software engineer for nearly 20 years, Andy has worked

on a diverse range of projects, including developing—along with the coauthor Peter Roxburgh—the first payments

service for Wireless Access Protocol (WAP) clients in the U.K. Peter, a technology specialist at Content Master, holds an

honors degree in business. He has contributed numerous articles on cutting-edge mobile technologies to professional

journals and Web sites.

Building Microsoft ASP.NET Applications for Mobile

Devices, Second Edition

Andy Wigley

Peter Roxburgh

PUBLISHED BY

Microsoft Press

A Division of Microsoft Corporation

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Redmond, Washington 98052-6399

Copyright © 2003 by Microsoft Corporation

All rights reserved. No part of the contents of this book may be reproduced or transmitted in any form or by

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comments to mspinput@microsoft.com.

FrontPage, JScript, Microsoft, Microsoft Press, Mobile Explorer, MSN, Visual Basic, Visual C++, Visual C#,

Visual J#, Visual Studio, Windows, and Windows NT are either registered trademarks or trademarks of

Microsoft Corporation in the United States and/or other countries. Other product and company names

mentioned herein may be the trademarks of their respective owners.

The example companies, organizations, products, domain names, e-mail addresses, logos, people, places,

and events depicted herein are fictitious. No association with any real company, organization, product,

domain name, e-mail address, logo, person, place, or event is intended or should be inferred.

Acquisitions Editor: Anne Hamilton

Project Editor: Kathleen Atkins

Technical Editor: Allen Jones

Body Part No. X09-45921

To Peter and Minda—wishing you every happiness

Acknowledgments

All authors are perfectionists. Although I'm proud of the first edition of this book, doing a second edition has

allowed me not only to write about the cool new stuff in the products but also to fix the things about the first

edition I didn't like. I'm grateful for the opportunity to write this book, and thanks for that goes to my

commissioning editor at Microsoft Press, Anne Hamilton.

Warm thanks to my project editor, Kathleen Atkins, who is not only a great editor but also an excellent

photographer. She took the photograph of me that accompanies the biography at the back of this book.

Thanks to the very thorough technical editing of Allen Jones, who has contributed hugely to making my

garbled technical explanations understandable and to getting the sample code into shape. Thanks also to all

the other excellent people on the Microsoft Press team: Jennifer Harris, Joel Panchot, Julie Hatley—and

apologies to anyone else I've missed.

In the Microsoft ASP.NET product group, thanks to Susan Chory, Andres Sanabria, and Matthew Gibbs for

their help and support—and thank you for a great product! At Content Master, thanks to my colleagues, who

remain a pleasure to work with, but particularly to David Glanville, my project manager and provider of weary

sighs as I overran on the time estimates for this book yet again. (Hey, we don't write these things for profit, do

we? It's just for FUN!)

The final paragraph of acknowledgments is always thanks to the author's family. Well, it should be the first

paragraph (but I don't quite feel able to break with tradition). I give heartfelt thanks to the center of my world,

my wonderful wife, Caroline, who provides me with support and encouragement, but more particularly, love

and companionship. And thanks to my wonderful daughters, Frances and Claire: I thought teenagers were

meant to be awful, but you two are really great.

Andy Wigley

Andy Wigley is a Principal Technologist at Content Master. He works exclusively with mobile technologies and

particularly loves researching, programming, and writing about applying Microsoft .NET to mobility solutions.

This interest has led him to devise and coauthor two books: the one you are holding now, and Microsoft .NET

Compact Framework (Core Reference) with Stephen Wheelwright (Microsoft Press, 2003), which focuses on

building rich client .NET applications for Pocket PC and Microsoft Windows CE .NET devices. He has

contributed to MSDN and other publications and regularly appears at conferences, presenting on applications

of mobile technology. He's a member of the Microsoft .NET Code Wise Community, supporting the developer

community with help and advice on mobility issues.

He lives with his wife, Caroline, and their two daughters, Frances and Claire, in North Wales. When he's not

at a computer, you'll find him rock climbing and walking in the mountains.

PowerTools

At Microsoft Press, we use tools to illustrate our books for software developers and IT professionals. Tools

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knowledge, there's no limit to creativity and innovation. Our tagline says it all: the tools you need to put

technology to work.

The manuscript for this book was prepared and galleyed using Microsoft Word. Pages were composed by

Microsoft Press using Adobe FrameMaker+SGML for Windows, with text in Garamond and display type in

Helvetica Condensed. Composed pages were delivered to the printer as electronic prepress files.

Cover Designer: Methodologie, Inc.

Interior Graphic Designer: James D. Kramer

Principal Compositor: Paula Gorelick

Interior Artist: Joel Panchot

Copy Editor: Jennifer Harris

Proofreader: nSight, Inc.

Indexer: Julie Hatley

Introduction

A few weeks ago, I got my hands on my first Microsoft Windows Powered Smartphone. It's a beautiful device

and a great phone, but the first thing I noticed (and the first thing anyone else I show it to notices) is that it has

a large, high-definition color screen. It's a far cry from the three-line black-and-white text screens that

everyone was using when the first edition of this book came out.

I expect that everyone will have mobile devices with large, color screens before long. When you use the

browser on these devices, you get a readable amount of information displayed, instead of having to scroll

continuously through it. The color and high definition make it pleasurable to the eye. These kinds of browsers

could not be used on mobile communications networks until recently because of the limited bandwidth, but

over the last year, faster GPRS and CDMA2000 networks have been launched throughout the world. Faster

networks and bigger color displays mean that you can create richer, more compelling Web content for mobile

browsers, which results in a more usable, more satisfying user experience. The mobile Web is beginning to

come of age.

I don't believe that the three-line monochrome browser is doomed, although I expect it will be seen less often

on consumer communications devices. However, Internet connectivity is turning up in more and more unlikely

places, so monochrome microbrowsers might still turn up in cars, on household appliances, and on portable

electronic gadgets.

The pace of change in mobile device technology is as fast as any other computing sector, if not faster. It's

nearly a year since the first version of what is now called ASP.NET Mobile Controls was launched (previously

called the Microsoft Mobile Internet Toolkit). In that time, we've seen smart new devices such as the Microsoft

Smartphone appear, and we've also seen a migration of lower-end devices from Wireless Application

Protocol (WAP) 1.1 to WAP 2.0, which introduces a brand new markup language, Extensible HyperText

Markup Language-Mobile Profile (XHTML-MP). ASP.NET Mobile Controls have handled these developments

comfortably. Microsoft has released configuration updates throughout the year, adding support for these new

devices and markup language and demonstrating how extensible this technology really is. You can develop

applications for these new devices using exactly the same techniques you used for WAP 1.1 devices. The

powerful abstract model the developer works with hides the details of the underlying devices, allowing you to

get on with creating great applications. If you wanted to sum up the capabilities of this technology, you'd say it

is extensible, adaptable, and customizable.

Time for Enterprise Mobility Applications?

There's momentum building from different directions that makes me believe that we'll see a huge increase in

the implementation of mobility solutions in the enterprise. The devices are getting cheaper, and they have

better capabilities. The telecommunications networks are getting faster, and with the spread of Wi-Fi (802.11

wireless LAN) throughout the workplace and at hot spots in public places such as airports, railway stations,

and coffee shops, enterprises can be confident that if they equip their personnel with capable devices such as

a Pocket PC Phone Edition PDA with integrated Wi-Fi, they'll never be far from a wireless network connection

with decent bandwidth. If you develop mobile Web applications, your users can access them from the

browser in the device over Wi-Fi when they are in a location where that's available. When users can't connect

to a wireless LAN, they can connect to a GPRS or CDMA2000 network operated by a phone network

operator. (GPRS and CDMA2000 connections are sometimes known as WWAN—wireless wide area

network—to distinguish them from WLAN, which is the proper term for Wi-Fi.)

So, good devices and good networks. However, the key ingredient from an enterprise point of view is good

software. Microsoft continues to make huge investments in mobility technology. The Microsoft Windows CE

operating system that drives Pocket PC and Windows Powered Smartphone devices continues to develop

and gain new capabilities. The latest version is called Windows CE .NET and includes support for the .NET

Compact Framework, which is a "light" version of the .NET Runtime for handheld devices. Using Microsoft

Visual Studio .NET 2003, you can build .NET applications that run on handheld devices, but only those that

support the runtime, which currently are Pocket PC and Windows CE .NET devices. To reach the majority of

browser-equipped mobile devices, you need ASP.NET Mobile Controls. Again using Visual Studio .NET 2003,

you can build applications that run not on the device, but on the Web server, and that send markup to the

browser on the device. The difference is "rich" vs. "reach." The .NET Compact Framework is about rich client

applications running on only some mobile devices; ASP.NET Mobile Controls are about mobile Web

applications that work with the majority of mobile devices.

With Visual Studio .NET, developers use a single integrated development environment to build applications

for each of these scenarios. Needless to say, building ASP.NET applications requires a different skill set than

building Windows Forms applications that run on the device, but they're both built on top of the .NET

Framework, so there's a lot of commonality that can make a developer's skills more transferable between

these different disciplines.

Who Is This Book For?

We've organized this book to serve two distinct audiences. The first group is wireless developers who already

have experience developing for handheld devices. You might be new to Microsoft development and probably

haven't yet used Visual Studio .NET. We've written Chapter 1, Chapter 2, and Chapter 3 primarily with you in

mind; they introduce ASP.NET and Visual Studio .NET and walk you through the development of some

mobile Web applications. Chapter 3 explains the essential information you'll need to understand to work with

mobile Web Forms.

The second audience is those who already have experience working with the .NET Framework and Visual

Studio .NET. If you've used ASP.NET before, you'll want to skim the first three chapters to get acquainted with

the Mobile Internet Designer but then dive straight into Chapter 4 to begin working with the mobile controls.

Regardless of your background, you need to be familiar with object-oriented programming. The .NET

Framework and everything built on it is completely object-oriented. ASP.NET Mobile Controls are classes,

just like everything else in ASP.NET, and you need to understand about classes, methods, properties, and

inheritance to make full use of the mobile controls and the .NET Framework.

Perhaps surprisingly, you don't need to be familiar with HyperText Markup Language (HTML) or Wireless

Markup Language (WML). More important is familiarity with a programming language such as Microsoft

Visual Basic or Microsoft Visual C#. We want to stress that you're writing object-oriented programs that just

happen to output markup. It's quite possible to write very sophisticated ASP.NET Mobile Controls applications

without ever having to dirty your hands with device-specific markup. Later on, some familiarity with HTML,

WML, or XHTML can be useful if you want to customize your application for specific handheld devices. One

of the things you can do with the Templates feature is send "raw" markup directly to the device. Advanced

developers who want to develop their own controls must, of course, be completely familiar with the markup

languages the devices use.

All the code examples in this book are written in C#, the programming language Microsoft developed

concurrently with the .NET Framework. Our hope is that Visual Basic developers won't feel alienated by this

focus on C#. In fact, C# code and Visual Basic code are structurally very similar, and apart from the obvious

language syntax differences, the C# samples should be very readable to a Visual Basic .NET developer. On

the Web site for this book, you'll find all the sample code from this book, with versions in C# and Visual Basic

.NET. The only exceptions to this are the custom control examples in Chapter 21 and Chapter 22. These are

only in C#, not because you can't use Visual Basic (or any other language the .NET Framework supports),

but because we didn't have time to write the code!

What's in This Book?

In Chapter 1, we set the scene by describing the challenges facing mobile Web application developers and

explaining how ASP.NET Mobile Controls resolve many of those issues. In Chapter 2, we continue the

introductory theme, giving you a brief tour of Visual Studio .NET, focusing on the capabilities introduced by

ASP.NET Mobile Controls. We show you the Mobile Internet Designer, which allows you to design your

application using a drag-and-drop GUI editor, dragging mobile controls from the Toolbox and dropping them

onto a mobile Web Forms page.

Chapter 3 is in many ways the most important chapter in this book. It gives you a grounding in the important

basics of ASP.NET Mobile Controls application development. This chapter is essential reading if you're new

to ASP.NET, explaining how the request-response interactions between client and server are handled and

how actions performed by the user of the mobile device translate into events, which you trap in your code in

the server. It's also important if you already have experience with ASP.NET as you'll learn much about the

differences between ASP.NET Web Forms and ASP.NET mobile Web Forms.

Chapter 4, Chapter 5, Chapter 6, and Chapter 7 take you through each of the standard mobile controls. The

intention here was to provide a handy mini-reference to each control so that you can find out—in one

place—how to include a control in a mobile Web Forms page using Extensible Markup Language (XML)

syntax and how to access the properties and methods of the control in your code. Each control includes one

or more sample applications demonstrating how to use it.

In Chapter 8, Chapter 9, and Chapter 10, we explain the features of ASP.NET Mobile Controls that allow you

to enhance the presentation of an application. These features can be categorized into three distinct areas of

functionality: styles, property overrides, and templates. Through styles, you can define colors and fonts to

apply to the output of controls, which will be honored on those browsers that support them. Property overrides

allow you to customize your application so that for specific models or types of client devices, different values

are assigned to control properties. Templates are a powerful feature, allowing you to customize the way a list

control is displayed or to insert device-specific markup into the output sent to a particular device.

Chapters 11 through 18 describe all the other areas of functionality that you will use as a mobile Web

developer. Topics include an introduction to data handling with Microsoft ADO.NET, testing and debugging

using Visual Studio .NET and mobile device emulators, good design practice and internationalizing your

application, handling state management, packaging and deploying your application, and writing secure

ASP.NET applications.

The last four chapters in this book, Chapters 19 through 22, describe the extensibility capabilities of ASP.NET

Mobile Controls. Chapter 19 describes how to extend support in ASP.NET Mobile Controls to new devices.

You can wait until Microsoft issues an update that supports your new device, or you can add support yourself

with the help of this chapter. Most of the material in these four chapters is for the advanced developer,

although Chapter 20 describes user controls, which you can use to easily develop reusable visual

components for mobile Web applications. Chapter 21 and Chapter 22 address the authoring of custom

mobile controls in code.

What Do I Need to Use This Book?

You'll need the following software to work through the samples in this book:

Microsoft Visual Studio .NET 2003, or Microsoft Visual Studio .NET 2002 and the Microsoft Mobile

Internet Toolkit 1.0. (Download the Mobile Internet Toolkit from

http://msdn.microsoft.com/library/default.asp?url=/downloads/list/netdevmit.asp.)

Microsoft Windows 2000, Microsoft Windows XP, or Microsoft .NET Server

The minimum hardware specification for your development PC is a Pentium II-class processor, 450 MHz with

a minimum of 128 MB (Windows 2000) or 256 MB (Windows XP or Windows .NET Server) of RAM. You'll

need around 5 GB of free hard disk space to install Visual Studio .NET 2003.

Visual Studio .NET 2003 includes emulators of a Windows CE .NET and a Pocket PC 2003 device. You can

use the browsers on these emulated devices for testing, so a real handheld device is not essential. You can

also perform initial testing of applications using Microsoft Internet Explorer. See Chapter 16 for details of

emulators from other sources that you can use for testing.

Sample Code

Most of the sample code in this book is written in C#. Many readers will prefer to use Visual Basic, so we have

implemented samples in Visual Basic as well and made all of them, both the C# and the Visual Basic

samples, available for download from this book's Web site. We hope that Visual Basic .NET developers will

download the samples and refer to those when reading the text. Fortunately, in .NET, the differences

between languages are not as pronounced as they used to be. C# and Visual Basic .NET applications are

structurally similar—only the language syntax changes—so descriptions in the text that describe how to use a

programming technique in C# should be understandable to someone referring to the Visual Basic version of a

sample.

You can download the samples from http://www.microsoft.com/mspress/books/6709.asp. Click the

companion content link in the More Information box on the right side of this page to bring up the companion

content Web page. This page has the link to download the sample code. See the instructions on that site for

how to install the samples on your own PC. Check this site for corrections and updates to the book as well.

Installing the MSDE .NET Framework Samples Database

Some of the samples in Chapter 11 use the pubs database, which installs with the Microsoft .NET Framework

SDK QuickStart samples. You don't need to install the SQL Server product on your development system

because the setup for the .NET Framework QuickStart samples will install the Microsoft SQL Server Desktop

Engine (MSDE), a stand-alone database server, if necessary.

To install the MSDE server and the sample databases, go to the C:\Program Files\Microsoft Visual Studio

.NET 2003\SDK\v1.1 folder, and double-click StartHere.htm. The Microsoft .NET Framework SDK welcome

page is displayed. Click on the QuickStarts, Tutorials, And Samples link. If you haven't already installed the

.NET Framework QuickStart samples, the page that is displayed shows two steps you must perform to install

the samples on your computer. First click Step 1: Install The .NET Framework Samples Database. When the

database has been set up, click Step 2: Set Up The QuickStarts to install all the sample databases and set

up the .NET Framework QuickStart tutorials.

Warning After you've installed the MSDE, be sure to install the latest service pack. Service Pack 3 or

later is necessary to ensure that your system does not get infected with the Slammer virus. See

http://msdn.microsoft.com/netframework/ downloads/updates/sdkfix/default.asp for details.

Using the Samples with Visual Studio .NET 2002

The samples have been developed using Visual Studio .NET 2003. You can't open the supplied project and

solution files with Visual Studio .NET 2002. If you're using Visual Studio .NET 2002 and the Mobile Internet

Toolkit 1.0, all the supplied sample code will still work, however. For any sample you want to use, you'll have

to create a new ASP.NET mobile Web application in Visual Studio .NET 2002 and then navigate to the

project folder and replace the .aspx, .aspx.cs (or .aspx.vb), Web.config, and (if supplied) global.asax and

global.asax.cs (or .asax.vb) files with those supplied in the sample. There should be no code changes

required to get the sample to work.

Support

Every effort has been made to ensure the accuracy of this book and the contents of the companion content.

Microsoft Press provides corrections for books and companion content through the World Wide Web at the

following address:

http://www.microsoft.com/mspress/support

To connect directly to the Microsoft Press Knowledge Base and enter a query, go to:

http://www.microsoft.com/mspress/support/search.asp

If you have comments, questions, or ideas regarding this book or the companion content or questions that

aren't answered by querying the Knowledge Base, please send them by e-mail to Microsoft Press at:

mspinput@microsoft.com

or by postal mail to:

Microsoft Press

Attn: Microsoft ASP.NET Mobile Devices Editor

One Microsoft Way

Redmond, WA 98052-6399

Please note that product support is not offered through the preceding mail address. For product support

information, please visit the Microsoft Support Web site at:

http://support.microsoft.com

Chapter 1: Introducing Microsoft ASP.NET for the

Mobile Web

Overview

Consider this scenario: Caroline, software engineer extraordinaire at A. Datum Corporation, is in trouble. After

a few high-profile successes, she earns recognition as a key employee. Her technical director becomes

interested in wireless Internet devices and asks her to build a mobile Web site that allows field personnel to

access their company data remotely. Figure 1-1 illustrates the challenge Caroline faces.

Figure 1-1: Designers of mobile applications face a bewildering number of choices.

After some initial research, Caroline decides Wireless Application Protocol (WAP) is the best approach.

Handsets are available, and industry support looks solid. Then the first headache appears: Caroline has to

learn a new markup language. She knows Hypertext Markup Language (HTML), but she finds WAP's

Wireless Markup Language (WML) so different that she discards her first few efforts until she succeeds in

working out how the "cards and decks" structure of a WML page works and figures out how to present

meaningful content in such a small display area. Although she wasn't naïve enough to assume that an

existing HTML Web site would transfer wholesale to a small device, she's surprised by the difficulty she has

creating a workable application given the device's small display and limited text-input capabilities. Eventually

the application takes shape, written using Microsoft Active Server Pages (ASP)—meaning that Caroline had

to refresh her knowledge of Microsoft Visual Basic Scripting Edition (VBScript) and write all the code required

to output the appropriate WML markup for her Web pages.

Soon the prototype is ready for beta testing, and Caroline is quite pleased with it. However, the testers report

that the application is confusing and unintuitive, which surprises Caroline, who carefully considered its

usability. After investigation, Caroline, who had used an emulation of a Nokia phone for testing, learns that

her users were working with Openwave browsers. Although both devices conform to WML 1.1 specifications,

the WML markup that offers the best usability on each browser differs slightly.

Caroline encounters even more problems. Field personnel at A. Datum Corporation's other main location

don't have a network operator providing WAP handsets in their metropolitan area. However, their network

operator does offer a mobile Internet service called M-mode service, which uses a different markup

language, compact HTML (cHTML). In addition, some of the prototype testers, despite seeing the potential of

the service, have recently acquired new two-way pagers, which offer text mobile Internet service—and now

they want to access the company data through the service their new pagers offer. Furthermore, the field

service managers recently received personal organizers with HTML browsers operating over wireless

modems, and they don't want to carry a WAP device as well. The technical director, looking a little

disappointed, thanks Caroline for her efforts and walks away scribbling on her indispensable personal digital

assistant (PDA), which is—of course—equipped with wireless Internet access, but not for WML.

At this point, Caroline quits the business in disgust and pursues her longtime ambition of guiding outdoor

expeditions. Once in the mountains, she finds with some relief that there are no computers in sight and that

she can't get mobile data coverage because of the surrounding peaks. Sometimes, however, lying in her

sleeping bag, she misses the excitement of software development and thinks back on the mobile project she

led at A. Datum Corporation. She realizes that the project would have succeeded if she'd had the following

capabilities:

A way to write one application that, when run, automatically generates the correct markup for all major

mobile browsers

A runtime smart enough to send not only valid markup, but also markup that actually yields optimum

usability on a particular manufacturer's browser

A presentation optimized for each type of browser—so that if, for example, the browser supports color,

the browser will use color as appropriate

The ability to lay out the user interface in a graphical user interface (GUI) editor

The ability to code in a proper object-oriented manner so that it's possible to cleanly isolate user interface

elements from application logic

Application logic that can be coded in a major language such as Microsoft Visual Basic .NET, C++, C#,

or even COBOL, with full access to data and the facilities of the underlying operating system

The ability to customize the user interface for any specific device

An extensible system that easily supports the next generation of mobile devices on the market as well as

their applications

These are features that ASP.NET Mobile Controls offer to overcome the obstacles to a successful

implementation that Caroline faced.

A Solution for the Wireless Muddle

ASP.NET Mobile Controls provide a solution for the "wireless muddle" that caused so many problems for the

developer in the preceding scenario. Wireless developers have to cope with a confusing variety of different

devices—small or large devices with different-size screens, in color or monochrome, and that require one of

the HTML, cHTML, WML, or XHTML markup languages, and quite often a specific "dialect" of one of those.

Since the first edition of this book came out early in 2002, the situation has gotten more confusing! At that

time, WAP/WML 1.1 browsers were commonplace in Europe, cHTML 1.0 browsers were predominant in

Japan, and Pocket PCs and Palm devices using an HTML 3.2 browser were the favored handheld devices for

businesses. A year later, you can walk into a shop of any of the major mobile network operators and be faced

with mobile phones with WML 1.1 or WML 1.3 browsers, Pocket PC Phone Edition and Microsoft Smartphone

devices with HTML browsers, and smartphones with WAP 2.0 browsers that require XHTML Mobile Profile

(XHTML-MP) markup, which is the successor to WML. Japanese i-mode technology, already a huge success

in Japan, is now being offered by operators in Europe and North America. PDAs and higher-end

Smartphones usually have HTML 3.2 browsers, although the version of Pocket Internet Explorer included in

the latest release of Microsoft's operating system for handheld devices, Microsoft Windows CE .NET, accepts

HTML 4.0 markup.

How then do you create an application that works with a significant number of these devices? If you're lucky

and you can control which devices are issued to your users, you can standardize on one device and one

technology. Few of us will have that luxury, however. Even if you build an application for one specific device,

the speed of technological change in this industry means that you will quite likely be looking at a major rewrite

a year down the line, when you want to take advantage of a new generation of handheld devices.

The answer is to make the technology on the client device an irrelevance—or to put it another way, to use

middleware on the Web server that takes care of worrying about the specific requirements of a particular

client device on your behalf. You develop a single application using ASP.NET Mobile Controls, deploy it to a

Windows Web server running Internet Information Services (IIS) and the Microsoft .NET Framework, and that

application works with over 200 different kinds of mobile devices from many different vendors, each with its

own specific requirements of markup language and screen size, as illustrated in Figure 1-2. Microsoft

regularly releases Device Update packs for ASP.NET Mobile Controls that add support for still more

handheld devices.

Figure 1-2: The ASP.NET Mobile Controls use adaptive rendering to support over 200 different handheld

devices from a single application.