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Figure 14-1: This Web page has a form

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Figure 14-2: In serverside programming, the result is an entirely different page

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This example points out a key difference between client-side and server-side processing: On the client (in JavaScript), your code resides on the Web page and modifies the same page In server-side programming (like PHP), the request form and the response are entirely different pages Typical PHP code involves building an entirely new page from scratch for the result Begin by looking at the XHTML source code: <!DOCTYPE html PUBLIC -//W3C//DTD XHTML 10 Strict//EN http://wwww3org/TR/xhtml1/DTD/xhtml1-strictdtd > <html lang= EN dir= ltr xmlns= http://wwww3org/1999/ xhtml > <head> <meta http-equiv= content-type content= text/xml; charset=utf-8 /> <title>nameFormhtml</title> </head> <body> <h1>Typical HTML Form</h1> <form action = greetUserphp method = get > <fieldset>

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14: Working with AJAX Data

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<input type = text name = userName value = Andy /> <button type = submit > submit </button> </fieldset> </form> </body> </html> It s nothing too shocking, but if you re used to writing forms for JavaScript, you ll see there are a few differences when you write a form for server-side processing: 1 No JavaScript is necessary It s possible to use client and server programming techniques together (in fact that is the point of AJAX), but it isn t necessary For this first example, all code will be processed on the server 2 Designate a target program in the form s action attribute When you create a form for JavaScript use, the action attribute is empty, indicating that all processing will happen on the current page For server-side processing, indicate the name of the program that will read the form data (in this case, greetUserphp) in the action attribute 3 Determine the transfer method There are two main ways to transmit form data to the receiving program The get mechanism embeds data in the URL This technique is useful for debugging (as the data is visible), but gets awkward for large forms The post technique is preferred for larger forms, as it sends the data through a less visible mechanism 4 Add a name attribute to form fields In client-side programming, you typically use the id attribute to identify fields Server-side programs prefer the name identifier You can (and often will) use both For this example, I ve named the single text field userName 5 Include a submit button For client-side processing, you normally use a standard button Serverside programming typically requires a submit button instead When the user clicks the submit button, all the data in the form is automatically packaged and sent to the program indicated in the form s action attribute

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Part III: Moving Up to AJAX

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If you get an error message when you submit this program, make sure you re running it correctly If the URL in your browser begins with file://, you re bypassing the server This method is fine in client-side programming, but it doesn t work when you re messing with the server You need to have an address that begins with http:// in order for server-side programs to work correctly

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Responding to the request

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When the user clicks the submit button of nameFormhtml, the form information is bundled and passed to the greetUserphp program If you look over the code for this program, you might find it surprisingly familiar: <!DOCTYPE html PUBLIC -//W3C//DTD XHTML 10 Strict//EN http://wwww3org/TR/xhtml1/DTD/xhtml1-strictdtd > <html lang= EN dir= ltr xmlns= http://wwww3org/1999/ xhtml > <head> <meta http-equiv= content-type content= text/xml; charset=utf-8 /> <title>greetUserphp</title> </head> <body> <h1>Greet user Response</h1> < php $userName = $_REQUEST[ userName ]; print <p>Hi, $userName!</p> ; > </body> </html> For the most part, a PHP program looks a lot like an XHTML page, because mostly that s what it is The general structure is just like XHTML There are only a few key differences 1 The filename must end with php This indicates to the server that the page isn t ordinary HTML but will need to be passed through the PHP interpreter before being sent to the user 2 The < php marker indicates a switch to PHP syntax Most of this page is standard XHTML (and can include CSS and JavaScript, too) In the middle of the page, I indicate that a section of code should be processed by PHP I signify this with the < php symbol (Occasionally you ll see other variations, but this almost always works) 3 Make a variable called $userName

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Part III: Moving Up to AJAX in Java Paint Denso QR Bar Code in Java Part III: Moving Up to AJAX

Part III: Moving Up to AJAX in Java

Paint Denso QR Bar Code in Java Part III: Moving Up to AJAX