Preface

AJAX is a complex phenomenon that means different things to different people. Computer users appreciate that their favorite websites are now friendlier and feel more responsive. Web developers learn new skills that empower them to create sleek web applications with little effort. Indeed, everything sounds good about AJAX!

At its roots, AJAX is a mix of technologies that lets you get rid of the evil page reload, which represents the dead time when navigating from one page to another. Eliminating page reloads is just one step away from enabling more complex features into websites, such as real-time data validation, drag and drop, and other tasks that weren’t traditionally associated with web applications. Although the AJAX ingredients are mature (the XMLHttpRequest object, which is the heart of AJAX, was created by Microsoft in 1999), their new role in the new wave of web trends is very young, and we’ll witness a number of changes before these technologies will be properly used to the best benefit of the end users. At the time of writing this book, the “AJAX” name is about just one year old.

AJAX isn’t, of course, the answer to all the Web’s problems, as the current hype around it may suggest. As with any other technology, AJAX can be overused, or used the wrong way. AJAX also comes with problems of its own: you need to fight with browser inconsistencies, AJAX‑specific pages don’t work on browsers without JavaScript, they can’t be easily bookmarked by users, and search engines don’t always know how to parse them. Also, not everyone likes AJAX. While some are developing enterprise architectures using JavaScript, others prefer not to use it at all. When the hype is over, most will probably agree that the middle way is the wisest way to go for most scenarios.

In AJAX and PHP: Building Responsive Web Applications, we took a pragmatic and safe approach by teaching relevant patterns and best practices that we think any web developer will need sooner or later. We teach you how to avoid the common pitfalls, how to write efficient AJAX code, and how to achieve functionality that is easy to integrate into current and future web applications, without requiring you to rebuild the whole solution around AJAX. You’ll be able to use the knowledge you learn from this book right away, into your PHP web applications.

We hope you’ll find this book useful and relevant to your projects. For the latest details and updates regarding this book, please visit its mini-site at http://ajaxphp.packtpub.com.

The book’s mini-site also contains additional free chapters and resources, which we recommend you check out when you have the time.

What This Book Covers

Chapter 1: AJAX and the Future of Web Applications is an initial incursion into the world of AJAX and the vast possibilities it opens up for web developers and companies, to offer a better experience to their users. In this chapter you’ll also build your first AJAX-enabled web page, which will give you a first look of the component technologies.

Chapter 2: Client-Side Techniques with Smarter JavaScript will guide you through the technologies you’ll use to build AJAX web clients, using JavaScript, the DOM, the XMLHttpRequest object, and XML. While not being a complete tutorial for these technologies, you’ll be put on the right track for using them together to build a solid foundation for your future applications.

Chapter 3: Server-Side Techniques with PHP and MySQL completes the theoretical foundation by presenting how to create smart servers to interact with your AJAX client. You’ll learn various techniques for implementing common tasks, including handling basic JavaScript security and error-handling problems.

Chapter 4: AJAX Form Validation guides you through creating a modern, responsive, and secure form validation system that implements both real-time AJAX validation and server-side validation on form submission.

Chapter 5: AJAX Chat presents a simple online chat that works exclusively using AJAX code, without using Java applets, Flash code, or other specialized libraries as most chat applications do these days.

Chapter 6: AJAX Suggest and Autocomplete builds a Google Suggest-like feature, that helps you quickly find PHP functions, and forwards you to the official help page for the chosen function.

Chapter 7: AJAX Real-Time Charting with SVG teaches you how to implement a real-time charting solution with AJAX and SVG. SVG (Scalable Vector Graphics) is a text-based graphics language that can be used to draw shapes and text.

Chapter 8: AJAX Grid teaches you how to build powerful AJAX-enabled data grids. You’ll learn how to parse XML documents using XSLT to generate the output of your grid.

Chapter 9: AJAX RSS Reader uses the SimpleXML PHP library, XML, and XSLT to build a simple RSS aggregator.

Chapter 10: AJAX Drag and Drop is a demonstration of using the script.aculo.us framework to build a simple list of elements with drag-and-drop functionality.

Appendix A: Preparing Your Working Environment teaches you how to install and configure the required software: Apache, PHP, MySQL, phpMyAdmin. The examples in this book assume that you have set up your environment and sample database as shown here.

At the book’s mini-site at http://ajaxphp.packtpub.com, you can find the online demos for all the book’s AJAX case studies.

What You Need for This Book

To go through the examples of this book you need PHP 5, a web server, and a database server. We have tested the code under several environments, but mostly with the Apache 2 web server, and MySQL 4.1 and MySQL 5 databases.

You can choose, however, to use another web server, or another database product, in which case the procedures presented in the chapters might not be 100% accurate. It is important to have PHP 5 or newer, because we use some features, such as Object Oriented Programming support, which aren’t available in older versions.

Please read Appendix A for more details about setting up your machine. If your machine already has the required software, you still need to read the final part of Appendix A, where you are instructed about creating a database that is used for the examples in this book.

Conventions

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.

There are three styles for code. 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:

// function calls the server using the XMLHttpRequest object 
function process()
{
  // retrieve the name typed by the user on the form
  name = document.getElementById(“myName”).value;
  // execute the quickstart.php page from the server
  xmlHttp.open(“GET”, “quickstart.php?name=” + name, false);  
  // make synchronous server request
  xmlHttp.send(null);  
  // read the response
  handleServerResponse();
}

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

// function calls the server using the XMLHttpRequest object 
function process()
{
  // retrieve the name typed by the user on the form
  name = document.getElementById(“myName”).value;
  // execute the quickstart.php page from the server  xmlHttp.open(“GET”, “quickstart.php?name=” + name, false);    // make synchronous server request   xmlHttp.send(null);    // read the response  handleServerResponse();
}

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

./configure --prefix=/usr/local/apache2 --enable-so --enable-ssl --with-ssl --enable-auth-digest

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”.

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.

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