PHP and WDDX - Page 3

An optional second parameter to wddx_serialize_value() lets you add a human- readable comment to the resulting packet. Listing 5.7 is a variant of Listing 5.5 that demonstrates this, with the output shown in Listing 5.8.

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Going to the Source

If you're using your web browser to view the examples in the section, you may wonder why the output you see on your screen doesn't match the output shown here. Well, that's because web browsers tend to hide tags that they don't know about; consequently, the WDDX tags generated during the serialization process are not displayed in the rendered web page.

The solution is fairly simple: use the browser's View Source command to view the raw source for the web page, and you should see the full uncensored output.

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Listing 5.7 Adding a Comment to a WDDX Packet

<?php
$flavors = array("strawberry", "chocolate", "raspberry", "peach");

print wddx_serialize_value($flavors, "A WDDX representation of my favorite
	icecream flavors");
?>

Listing 5.8 A WDDX Packet with a Human-Readable Comment in the Header

<wddxPacket version='1.0'>
   <header>
      <comment>
	     A WDDX representation of my favorite icecream flavors
      </comment>
   </header>
    <data>
      <array length='4'>
         <string>strawberry</string>
         <string>chocolate</string>
         <string>raspberry</string>
         <string>peach</string>
      </array>
   </data>
</wddxPacket>

The wddx_serialize_vars() Function

The wddx_serialize_value() function cannot accept more than a single variable. However, it's also possible to serialize more than one variable at a time with the wddx_serialize_vars() function, which can accept multiple variables for serialization as function arguments. Listing 5.9 demonstrates how this works.

Listing 5.9 Serializing Multiple Values with wddx_serialize_vars()

<?php
$phrase = "The game's afoot";
$animals = array("parrot" => "Polly", "hippo" => "Hal", "dog" => "Rover",
"squirrel" => "Sparky");

print wddx_serialize_vars("phrase", "animals");
?>

Note that wddx_serialize_vars() requires the names of the variables to be serialized as string arguments.

Listing 5.10 displays the result of a wddx_serialize_vars() run.

Listing 5.10 A WDDX Packet Generated via wddx_serialize_vars()

<wddxPacket version='1.0'>
<header/>
   <data>
      <struct>
         <var name='phrase'>
            <string>The game's afoot</string>
         </var>
         <var name='animals'>
            <struct>
               <var name='parrot'>
                  <string>Polly</string>
               </var>
               <var name='hippo'>
                  <string>Hal</string>
               </var>
               <var name='dog'>
                  <string>Rover</string>
               </var>
               <var name='squirrel'>
                  <string>Sparky</string>
               </var>
            </struct>
         </var>
      </struct>
   </data>
</wddxPacket>

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