AJAX and PHP

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AJAX Real-Time Charting with SVG coordinates, and based on that data, the server generates a new set. This simulates pretty well a real-world scenario. The previously generated coordinates are sent via GET as two parameters named lastX and lastY. To test the server-side functionality independently of the rest of the solution, try loading http://localhost/ajax/svg_chart/svg_chart.php?lastX=5&lastY=44: Figure 7.3: The Server generating a New Set of Coordinates for the Client On the client, everything starts with index.html, which is really simple; all it does is to load the SVG file. The best way to do this at the moment is by using an element, which isn't supported by W3C (you can also use and , but they are more problematic—see http://www.w3schools.com/svg/svg_inhtml.asp): And here it comes—chart.svg. This file isn't very impressive by itself, because it uses functionality provided by the JavaScript files (notice the onload event), but it includes the chart title: SVG with AJAX and PHP Demo chart.svg references two JavaScript files: ajaxRequest.js contains the engine that implements asynchronous HTTP request functionality using the XMLHttpRequest object. This engine is used by realTimeChart.js to get new chart data from the server when the Firefox web browser is used. For the Adobe SVG and Apache Batik implementations, we use specific functionality provided by these engines through their getURL methods instead. See the updateChart method in realTimeChart.js for details. The code in ajaxRequest.js contains a different coding pattern than what you've met so far in the book. What is important to understand is: 200 www.it-ebooks.info
Chapter 7 • All HTTP requests go through a single XMLHttpRequest instance, rather than automatically creating new XMLHttpRequest objects for each call, as implemented in other patterns. This way we are guaranteed to receive responses in the same order as they were requested, which is important for our charting application (and for any other application where the responses must come in order). If the connection is busy processing a previous request, our code waits for one second, and then retries. This technique is also friendly in its use of the web server resources. • The ajaxRequest() method receives as parameter the URL to connect to, and a reference to the callback function to be called when the server response is received. This is a good technique to implement when you need the flexibility to access the same functionality from several sources. • The handleGettingResults() method is defined inside the ajaxRequest method. This is one of JavaScript's features that enable emulating OOP functionality. So far we haven't used these features because we think they bring real benefits only when writing large applications and they require a longer learning curve for programmers inexperienced in OOP techniques. If you like this technique, you'll find it easy to implement it in your applications. realTimeChart.js contains all the functionality that generates the SVG chart. The code contains detailed comments about the specific techniques. Here is a short description of each of the methods: • init() is called when the page loads to perform the chart initialization. This method generates the SVG code for the chart axis and builds the initial structure for the whole chart. Initially, the numbers for the axis units are drawn with white font to make them invisible. We need this because of a problem in the Firefox SVG implementation that doesn't allow calculating the text size and positioning it correctly before it is rendered on the screen. Using pre-calculated values isn't an option because the grid is configurable and its axis can be populated with different values. To overcome this problem, init() uses setTimeout() to execute refreshXYIndexes() after half a second. • refreshXYIndexes() is able to calculate the correct positions for the text on the axis units, even with Firefox 1.5. After it sets the new coordinates, it changes the color of the text from white to black, making it visible. • createPointInfo() is called from the onmouseover function of the chart nodes to display the node coordinates. • removePointInfo() is called from the onmouseout event to remove the displayed node coordinates. • updateChart() is the function that initiates the asynchronous request. The getURL method is used if available (this method is supported by Adobe SVG and Apache Batik). Otherwise, the ajaxRequest method (from ajaxRequest.js) is used to make the request. When calling the server, the pair of previously generated coordinates is sent via GET, which the server uses to calculate the new values. 201 www.it-ebooks.info
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AJAX and PHP Building Responsive We
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About the Authors Cristian Darie is
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About the Reviewers Emilian Balanes
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Table of Contents Preface 1 Chapter
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Table of Contents Chapter 6: AJAX S
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Preface AJAX is a complex phenomeno
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Preface What You Need for This Book
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Preface Errata Although we have tak
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1 AJAX and the Future of Web Applic
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Chapter 1 Because end-user satisfac
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Chapter 1 Three points for you to k
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Chapter 1 With JavaScript, develope
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interrupting the user from his or h
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• Creating simple online chat sol
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Chapter 1 done typing. (This method
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Chapter 1 All exercises from this b
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etrieve the user name $name = $_GET
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Chapter 1 If you're curious to test
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Chapter 1 request. In our case, thi
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2 Client-Side Techniques with Smart
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AJAX Foundations: JavaScript and
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Chapter 2 • Because there is no s
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Time for Action—Using JavaScript
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Even More DOM In the previous exerc
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Chapter 2 What Just Happened? Well,
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Chapter 2 font-size: 10pt; } .Table
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Chapter 2 Creating the XMLHttpReque
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Chapter 2 You could, for example, c
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You will learn the most interesting
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Chapter 2 The safer version of proc
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Chapter 2 4. Create a file call
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Chapter 2 Figure 2.6: The Four HTTP
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Chapter 2 } } else { // display sta
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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
Page 161 and 162: Chapter 5 // default the last id to
Page 163 and 164: } Chapter 5 ' DATE_FORMAT(posted_on
Page 165 and 166: Chapter 5 AJAX Chat Your b
Page 167 and 168: * function called when the Send but
Page 169 and 170: } } // retrieve the arrays from the
Page 171 and 172: Chapter 5 } } } // call server asyn
Page 173 and 174: Chapter 5 If you analyze the code f
Page 175 and 176: The business logic behind chat.php
Page 177 and 178: 6 AJAX Suggest and Autocomplete Sug
Page 179 and 180: Chapter 6 The clever part of the Ja
Page 181 and 182: Chapter 6 6. Create another file na
Page 183 and 184: Chapter 6 { } a { } font-weight: bo
Page 185 and 186: Chapter 6 } { // try to create XMLH
Page 187 and 188: Chapter 6 } } } } { } displayError(
Page 189 and 190: Chapter 6 div += "" + "" + crtFunct
Page 191 and 192: } } // select the new suggestion an
Page 193 and 194: Chapter 6 } } else // FF if (oText.
Page 195 and 196: Chapter 6 Figure 6.4: PHP Documenta
Page 197 and 198: Chapter 6 We have talked about cach
Page 199 and 200: Chapter 6 visible, we need to scrol
Page 201 and 202: 7 AJAX Real-Time Charting with SVG
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Page 205 and 206: Chapter 7 Figure 7.2: SVG Charting
Page 207 and 208: Chapter 7 } { xmlHttp.onreadystatec
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Page 211: Chapter 7 } // Supported by Mozilla
Page 215 and 216: 8 AJAX Grid Data grids have always
Page 217 and 218: Chapter 8 Figure 8.2: AJAX Grid in
Page 219 and 220: $name = $_GET['name']; // update th
Page 221 and 222: } Chapter 8 if (!isset($_SESSION['r
Page 223 and 224: Chapter 8 # editId(, true) Edit
Page 225 and 226: Chapter 8 } // this should work for
Page 227 and 228: } Chapter 8 if(editableId) editId(e
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Page 231 and 232: Chapter 8 On the client, this data
Page 233 and 234: Chapter 8 save() and undo() are hel
Page 235 and 236: 9 AJAX RSS Reader In the last few y
Page 237 and 238: Chapter 9 Figure 9.1: Managing RSS
Page 239 and 240: header('Pragma: no-cache'); header(
Page 241 and 242: Chapter 9 Loading feed... Abou
Page 243 and 244: Chapter 9 } // continue if the proc
Page 245 and 246: Chapter 9 } width: 410px; backgroun
Page 247 and 248: And finally, we send the HTTP reque
Page 249 and 250: 10 AJAX Drag and Drop When drag-and
Page 251 and 252: Chapter 10 The Prototype features a
Page 253 and 254: Chapter 10 When dropping a task on
Page 255 and 256: Chapter 10 DROP HERE TO DELETE
Page 257 and 258: header('Expires: Fri, 25 Dec 1980 0
Page 259 and 260: Chapter 10 } } } else if (action ==
Page 261 and 262: 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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AJAX and PHP

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