Using Perl With WDDX - All Mixed Up
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The flip side of whatever you just read is, of course, deserialization. Perl's WDDX.pm module accomplishes this via its deserialize() method, which can be used to convert WDDX-based language-independent data representations into native data types.

Consider the following example, which demonstrates how a WDDX packet containing a string value is deserialized into a Perl scalar variable:

#!/usr/bin/perl

# use WDDX module
use WDDX;

# create WDDX object
$wddx = new WDDX;

# simulate a WDDX packet
$packet = "<wddxPacket version='1.0'><header/><data><string>Robin
Hood</string></data></wddxPacket>";

# deserialize packet into WDDX string object
$obj = $wddx->deserialize($packet);

# check object type 
if ($obj->type eq "string")
{
        # and print as scalar
        print $obj->as_scalar;
}

In this case, the WDDX packet is first deserialized into a WDDX string object, and then the string object's as_scalar() method is used to convert the string object into a native Perl scalar. Note that the deserialized object exposes a type() method, which can be used to identify the data type and process it appropriately.

Here's the output:

Robin Hood

This deserialization works with arrays too - as the following example demonstrates:

#!/usr/bin/perl

# use WDDX module
use WDDX;

# create WDDX object
$wddx = new WDDX;

# simulate a WDDX packet
$packet = "<wddxPacket version='1.0'> <header/> <data> <array
length='3'> <string>red</string> <string>blue</string>
<string>green</string> </array> </data> </wddxPacket>";

# deserialize packet into WDDX array object
$obj = $wddx->deserialize($packet);

# get number of elements in array
$length = $obj->length();

# get reference to native Perl array
$arrayref = $obj->as_arrayref();

# iterate through array and print elements
for ($i=0; $i<$length; $i++)
{
        print "$$arrayref[$i]\n";
}

Here's the output:

red
blue
green

Wanna really cause some heartburn? Try serializing an array of arrays,

#!/usr/bin/perl

# include module
use WDDX;

# create WDDX object
my $wddx = new WDDX;

# create an array
my @arr = ( $wddx->string("huey"), $wddx->string("dewey"),
$wddx->boolean(1) );

# create a WDDX hash
$obj = $wddx->struct(
              {
                "str" => $wddx->string("Abracadabra"),
                "num" => $wddx->number(23),
                "arr" => $wddx->array(\@arr)
              }
);

# serialize and print object
print $wddx->serialize($obj);

and see what you get:

<wddxPacket version='1.0'>
<header/>
<data>
<struct>
<var name='num'>
<number>23</number>
</var>
<var name='str'>
<string>Abracadabra</string>
</var>
<var name='arr'>
<array length='3'>
<string>huey</string>
<string>dewey</string>
<boolean value='true'/>
</array>
</var>
</struct>
</data>
</wddxPacket>

This is a hash with three keys, one containing a string, the second a number, and the third an array. Now, try deserializing the WDDX packet generated from the code above.

#!/usr/bin/perl

# use WDDX module
use WDDX;

# create WDDX object
$wddx = new WDDX;

# simulate a WDDX packet
$packet = " <wddxPacket version='1.0'><header/><data><struct><var
name='num'><number>23</number></var><var
name='str'><string>Abracadabra</string></var><var name='arr'><array
length='3'><string>huey</string><string>dewey</string><boolean
value='true'/></array></var></struct></data></wddxPacket>";

# deserialize packet into WDDX array object
$obj = $wddx->deserialize($packet);

# get reference to native Perl hash
$hashref = $obj->as_hashref();

# get keys
@k = $obj->keys();

# print keys and type of corresponding values
foreach $k (@k)
{
        print "$k --> " . $obj->get($k)->type . "\n";
}

Here's what you should see:

num --> number
str --> string
arr --> array

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