Chapter 1 is a brief introduction to AJAX technology and DWR. It also discusses the DWR community and describes briefly what information can be found about DWR on the Internet.

Chapter 2 describes DWR features that we use in the samples of this book—a high-level view of how DWR makes a developer's life easier. It discusses reverse AJAX, DWR JavaScript libraries, converters, creators, filters, and signatures. It also contains a section on integrating DWR with other projects and another on security.

Chapter 3 sets the stage for development by describing how to set up the development environment and how to test and debug our sample applications. It covers DWR-supported browsers and environments, configuration, error handling, packaging, and deployment.

Chapter 4 is the first chapter dedicated to sample code. The examples in this chapter include typical user interface elements such as tables and lists, and how they can be implemented using DWR. It also has an example for field completion.

Chapter 5 discusses how to use DWR in more advanced user interface elements such as forms, navigation tree, and scrolling a map.

Chapter 6 shows how DWR applications are integrated to a database, a web service, or a messaging system.

Chapter 7 includes two sample applications: Collaborative Book Authoring, which shows how DWR is used to create a web based multi-user authoring environment, and Chatroom—a typical multi-user chat room application using DWR.

This book is for professional Java developers and architects who want to learn about DWR by examples. Several skills are needed or are beneficial to get the most out of this book.

First of all, Java development skills are needed. Especially web development using Java technologies like Java Enterprise Edition (JEE), Servlets, and JSPs. Experience about other web technologies like JavaScript, HTML, and CSS is also useful.

Eclipse tooling should be familiar and other useful skills are knowledge about JEE application servers and experience about common technologies like XML.

Knowledge about the basics of AJAX technology is helpful. However, the basics of AJAX are introduced in this book.

This book is written for competent Java developers and assumes that you are a professional rather than a hobbyist. You should be familiar with the concepts of programming, Web 2.0, and AJAX.

In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text are shown as follows: "We can include other contexts through the use of the include directive."

A block of code will be set as follows:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC
"-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN"
"http://getahead.org/dwr/dwr20.dtd">
<dwr>
<allow>
<create creator="new" javascript="HorizontalMenu">
<param name="class" value="samples.HorizontalMenu" />
</create>
</allow>
</dwr>

When we wish to draw your attention to a particular part of a code block, the relevant lines or items will be made bold:

public boolean submitOrder(String name, String address, String creditCardNumber, String expiryDate) {
CreditCardValidatorSoapProxy ccValidatorProxy = new CreditCardValidatorSoapProxy();
int rv = -1;
try {
rv = ccValidatorProxy.validCard(creditCardNumber, expiryDate.replace("/", ""));
if (rv != 0) {
System.out.println("Credit card check failed: " + rv);
}
} catch (RemoteException e) {
e.printStackTrace();
}
if(rv==0)

{
//credit card valid, submit to order system
new OrderSystem(name,address,creditCardNumber,expiryDate);
}
return rv == 0;
}

Any command-line input and output is written as follows:

deploy -user system -password manager deploy d:\temp\HelloWorldServlet.war

New terms and important words are introduced in a bold-type font. Words that you see on the screen, in menus or dialog boxes for example, appear in our text like this: "clicking the Next button moves you to the next screen".

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