AJAX and PHP

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AJAX and the Future of Web Applications Understanding the way people's brains work would be the key to building the ultimate software applications. While we're far from that point, what we do understand is that end users need intuitive user interfaces; they don't really care what operating system they're running as long as the functionality they get is what they expect. This is a very important detail to keep in mind, as many programmers tend to think and speak in technical terms even when working with end users (although in a typical development team the programmer doesn't interact directly with the end user). If you disagree, try to remember how many times you've said the word database when talking to a non-technical person. By observing people's needs and habits while working with computer systems, the term software usability was born—referring to the art of meeting users' interface expectations, understanding the nature of their work, and building software applications accordingly. Historically, usability techniques were applied mainly to desktop applications, simply because the required tools weren't available for web applications. However, as the Internet gets more mature, the technologies it enables are increasingly potent. Modern Internet technologies not only enable you to build a better online presence, but also allow building better intranet/dedicated applications. Having friendly websites is crucial for online business, because the Internet never sleeps, and customers frequently migrate to the next "big thing" that looks better or feels to move faster. At the same time, being able to build friendly web interfaces gives alternative options for intranet software solutions, which were previously built mainly as desktop applications. Building user-friendly software has always been easier with desktop applications than with web applications, simply because the Web was designed as a means for delivering text and images, and not complex functionality. This problem has gotten significantly more painful in the last few years, when more and more software services and functionality are delivered via the Web. Consequently, many technologies have been developed (and are still being developed) to add flashy lights, accessibility, and power to web applications. Notable examples include Java applets and Macromedia Flash, which require the users to install separate libraries into their web browsers. Delivering Functionality via the Web Web applications are applications whose functionality is processed on a web server, and is delivered to the end users over a network such as the Internet or an intranet. The end users use a thin client (web browser) to run web applications, which knows how to display and execute the data received from the server. In contrast, desktop applications are based on a thick client (also called a rich client or a fat client), which does most of the processing. Web applications evolve dreaming that one day they'll look and behave like their mature (and powerful) relatives, the desktop applications. The behavior of any computer software that interacts with humans is now even more important than it used to be, because nowadays the computer user base varies much more than in the past, when the users were technically sound as well. Now you need to display good looking reports to Cindy, the sales department manager, and you need to provide easy-to-use data entry forms to Dave, the sales person. 8 www.it-ebooks.info
Chapter 1 Because end-user satisfaction is all that matters, the software application you build must be satisfactory to all the users that interact with it. As far as web applications are concerned, their evolution-to-maturity process will be complete when the application's interface and behavior will not reveal whether the functionality is delivered by the local desktop or comes through fiber or air. Delivering usable interfaces via the Web used to be problematic simply because features that people use with their desktop application, such as drag and drop, and performing multiple tasks on the same window at the same time, were not possible. Another problem with building web applications is standardization. Today, everything web-accessible must be verified with at least two or three browsers to ensure that all your visitors will get the full benefit of your site. Advantages of Web Applications Yes, there are lots of headaches when trying to deliver functionality via the Web. But why bother trying to do that in the first place, instead of building plain desktop applications? Well, even with the current problems that web applications have with being user-friendly, they have acquired extraordinary popularity because they offer a number of major technological advantages over desktop applications. • Web applications are easy and inexpensive to deliver. With web applications, a company can reduce the costs of the IT department that is in charge of installing the software on the users' machines. With web applications, all that users need is a computer with a working web browser and an Internet or intranet connection. • Web applications are easy and inexpensive to upgrade. Maintenance costs for software have always been significant. Because upgrading an existing piece of software is similar to installing a new one, the web applications' advantages mentioned above apply here as well. As soon as the application on the server machine is upgraded, everyone gets the new version. • Web applications have flexible requirements for the end users. Just have your web application installed on a server—any modern operating system will do—and you'll be able to use it over the Internet/Intranet on any Mac, Windows, or Linux machine and so on. If the application is properly built, it will run equally well on any modern web browser, such as Internet Explorer, Mozilla Firefox, Opera, or Safari. • Web applications make it easier to have a central data store. When you have several locations that need access to the same data, having all that data stored in one place is much easier than having separate databases in each location. This way you avoid potential data synchronization operations and lower security risks. In this book we'll further investigate how to use modern web technologies to build better web applications, to make the most out of the possibilities offered by the Web. But before getting into the details, let's take a short history lesson. 9 www.it-ebooks.info
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Page 3 and 4: AJAX and PHP Building Responsive We
Page 5 and 6: About the Authors Cristian Darie is
Page 7 and 8: About the Reviewers Emilian Balanes
Page 9 and 10: Table of Contents Preface 1 Chapter
Page 11 and 12: Table of Contents Chapter 6: AJAX S
Page 13 and 14: Preface AJAX is a complex phenomeno
Page 15 and 16: Preface What You Need for This Book
Page 17 and 18: Preface Errata Although we have tak
Page 19: 1 AJAX and the Future of Web Applic
Page 23 and 24: Chapter 1 Three points for you to k
Page 25 and 26: Chapter 1 With JavaScript, develope
Page 27 and 28: interrupting the user from his or h
Page 29 and 30: • Creating simple online chat sol
Page 31 and 32: Chapter 1 done typing. (This method
Page 33 and 34: Chapter 1 All exercises from this b
Page 35 and 36: etrieve the user name $name = $_GET
Page 37 and 38: Chapter 1 If you're curious to test
Page 39 and 40: Chapter 1 request. In our case, thi
Page 41 and 42: 2 Client-Side Techniques with Smart
Page 43 and 44: AJAX Foundations: JavaScript and
Page 45 and 46: Chapter 2 • Because there is no s
Page 47 and 48: Time for Action—Using JavaScript
Page 49 and 50: Even More DOM In the previous exerc
Page 51 and 52: Chapter 2 What Just Happened? Well,
Page 53 and 54: Chapter 2 font-size: 10pt; } .Table
Page 55 and 56: Chapter 2 Creating the XMLHttpReque
Page 57 and 58: Chapter 2 You could, for example, c
Page 59 and 60: You will learn the most interesting
Page 61 and 62: Chapter 2 The safer version of proc
Page 63 and 64: Chapter 2 4. Create a file call
Page 65 and 66: Chapter 2 Figure 2.6: The Four HTTP
Page 67 and 68: Chapter 2 } } else { // display sta
Page 69 and 70: Chapter 2 } { // try to create XMLH
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Chapter 2 The responseXML method of
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Chapter 2 Figure 2.10: Opera Displa
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I admit that the following piece of
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3 Server-Side Techniques with PHP a
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Chapter 3 } for (var i=0; i
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Chapter 3 // create the element $b
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Chapter 3 // create the root eleme
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Chapter 3 // read a file from the s
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Chapter 3 Figure 3.3: PHP Parameter
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Chapter 3 Without the customized er
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} } // display the error in case of
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Chapter 3 Figure 3.7: Connecting to
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Chapter 3 } } // continue only if H
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Chapter 3 You can make Firefox list
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Chapter 3 } "MSXML2.XMLHTTP.4.0", "
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'TEXT: ' . $errStr . chr(10) . 'LOC
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etrieve the parameters $num = 1; //
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Chapter 3 Figure 3.16: Flowchart De
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} Chapter 3 // only continue if xml
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} throw(response.length == 0 ? "Ser
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function process() { // ... if (req
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Chapter 3 Working with MySQL A back
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Chapter 3 Figure 3.17: Executing SQ
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Chapter 3 SELECT user_id, user_name
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3. In your foundations folder, crea
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Chapter 3 After these commands exec
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Chapter 3 • friendly.php is a PHP
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This example requires a JavaSc
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} } // try to connect to the server
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Chapter 3 } // create HTML-formatte
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Chapter 3 On the server side, all t
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4 AJAX Form Validation Validating i
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Chapter 4 Always validate user inpu
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Chapter 4 Figure 4.4: Successful Su
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Chapter 4 .left { margin-left: 150p
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Chapter 4 value="" />
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Registration Successfull! <<
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Chapter 4 } } { // display error me
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Chapter 4 require_once ('config.php
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Chapter 4 } { } $_POST['txtBthDay']
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Chapter 4 } } ?> return ($value ==
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Chapter 4 The field ID and value re
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Chapter 4 If we are dealing with cl
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5 AJAX Chat We are living in a worl
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Chapter 5 Implementing AJAX Chat We
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Chapter 5 // default the last id to
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} Chapter 5 ' DATE_FORMAT(posted_on
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Chapter 5 AJAX Chat Your b
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* function called when the Send but
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} } // retrieve the arrays from the
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Chapter 5 } } } // call server asyn
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Chapter 5 If you analyze the code f
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The business logic behind chat.php
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6 AJAX Suggest and Autocomplete Sug
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Chapter 6 The clever part of the Ja
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Chapter 6 6. Create another file na
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Chapter 6 { } a { } font-weight: bo
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Chapter 6 } { // try to create XMLH
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Chapter 6 } } } } { } displayError(
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Chapter 6 div += "" + "" + crtFunct
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} } // select the new suggestion an
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Chapter 6 } } else // FF if (oText.
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Chapter 6 Figure 6.4: PHP Documenta
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Chapter 6 We have talked about cach
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Chapter 6 visible, we need to scrol
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7 AJAX Real-Time Charting with SVG
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Chapter 7 Figure 7.1: SVG Chart The
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Chapter 7 Figure 7.2: SVG Charting
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Chapter 7 } { xmlHttp.onreadystatec
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} } // sets the X and Y attributes
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Chapter 7 } // Supported by Mozilla
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Chapter 7 • All HTTP requests go
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8 AJAX Grid Data grids have always
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Chapter 8 Figure 8.2: AJAX Grid in
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$name = $_GET['name']; // update th
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} Chapter 8 if (!isset($_SESSION['r
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Chapter 8 # editId(, true) Edit
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Chapter 8 } // this should work for
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} Chapter 8 if(editableId) editId(e
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} color: darkblue; text-align: righ
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Chapter 8 On the client, this data
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Chapter 8 save() and undo() are hel
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9 AJAX RSS Reader In the last few y
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Chapter 9 Figure 9.1: Managing RSS
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header('Pragma: no-cache'); header(
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Chapter 9 Loading feed... Abou
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Chapter 9 } // continue if the proc
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Chapter 9 } width: 410px; backgroun
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And finally, we send the HTTP reque
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10 AJAX Drag and Drop When drag-and
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Chapter 10 The Prototype features a
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Chapter 10 When dropping a task on
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Chapter 10 DROP HERE TO DELETE
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header('Expires: Fri, 25 Dec 1980 0
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Chapter 10 } } } else if (action ==
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Chapter 10 11. Load http://localhos
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details are saved using a cache sys
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Chapter 10 Summary This is it! You'
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A Preparing Your Working Environmen
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Appendix A During installation you'
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Before going through any case studi
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Appendix A Preparing Your *nix Play
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8. Finally, point your web browser
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2. Write ajax in the Create a new d
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Index A abort() method, XMLHttpRequ
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exception handling, JavaScript, 43
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PHP Parameters and Error Handling r
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updateChart() function, realTimeCha
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