<?xml version="1.0" encoding="UTF-8"?>
<contacts>
    <contact id="1">
        <name>John Doe</name>
        <phone>123-456-7890</phone>
        <address>
            <street>123 JFKStreet</street>
            <city>Any Town</city>
            <state>Any State</state>
            <zipCode>12345</zipCode>
        </address>
    </contact>
</contacts>

{
   "contacts" : {
      "contact" : {
         "@attributes" : {
            "id" : "1"
         }, 
         "name" : "John Doe", 
         "phone" : "123-456-7890", 
         "address" : {
            "street" : "123 JFK Street", 
            "city" : "Any Town", 
            "state" : "Any State", 
            "zipCode" : "12345"
         }
      }
   }
}

var result = httpRequest.responseText;
jsonResponse = eval('(' + result + ')');

require_once 'json/JSON.php';
// Internal program-specific Debug option.
define ("DEBUG", false);
// Maximum Recursion Depth that we can allow.
define ("MAX_RECURSION_DEPTH_ALLOWED", 25);
// An empty string
define ("EMPTY_STR", ");
// SimpleXMLElement object property name for attributes
define ("SIMPLE_XML_ELEMENT_OBJECT_PROPERTY_FOR_ATTRIBUTES", "@attributes");
// SimpleXMLElement object name.
define ("SIMPLE_XML_ELEMENT_PHP_CLASS", "SimpleXMLElement");

public static function transformXmlStringToJson($xmlStringContents) {
    $simpleXmlElementObject = simplexml_load_string($xmlStringContents); 


    if ($simpleXmlElementObject == null) {
        return(EMPTY_STR);
    }


    $jsonOutput = EMPTY_STR; 


    // Let us convert the XML structure into PHP array structure.
    $array1 = xml2json::convertSimpleXmlElementObjectIntoArray($simpleXmlElementObject);


    if (($array1 != null) & (sizeof($array1) > 0)) { 
        // Create a new instance of Services_JSON
        $json = new Services_JSON();
        // Let us now convert it to JSON formatted data.
        $jsonOutput = $json->encode($array1);
    } // End of if (($array1 != null) & (sizeof($array1) > 0))


    return($jsonOutput); 
} // End of function transformXmlStringToJson

public static function convertSimpleXmlElementObjectIntoArray($simpleXmlElementObject,
&$recursionDepth=0) { 
  // Keep an eye on how deeply we are involved in recursion.


  if ($recursionDepth > MAX_RECURSION_DEPTH_ALLOWED) {
    // Fatal error. Exit now.
    return(null);
  }


  if ($recursionDepth == 0) {
    if (get_class($simpleXmlElementObject) != SIMPLE_XML_ELEMENT_PHP_CLASS) {
      // If the external caller doesn't call this function initially 
      // with a SimpleXMLElement object, return now. 
      return(null); 
    } else {
      // Store the original SimpleXmlElementObject sent by the caller.
      // We will need it at the very end when we return from here for good.
      $callerProvidedSimpleXmlElementObject = $simpleXmlElementObject;
    }
  } // End of if ($recursionDepth == 0) { 


  if (get_class($simpleXmlElementObject) == SIMPLE_XML_ELEMENT_PHP_CLASS) {
    // Get a copy of the simpleXmlElementObject
    $copyOfsimpleXmlElementObject = $simpleXmlElementObject;
    // Get the object variables in the SimpleXmlElement object for us to iterate.
    $simpleXmlElementObject = get_object_vars($simpleXmlElementObject);
  }


  // It needs to be an array of object variables.
  if (is_array($simpleXmlElementObject)) {
    // Initialize the result array.
    $resultArray = array();
    // Is the input array size 0? Then, we reached the rare CDATA text if any.
    if (count($simpleXmlElementObject) <= 0) {
      // Let us return the lonely CDATA. It could even be
      // an empty element or just filled with whitespaces.
      return (trim(strval($copyOfsimpleXmlElementObject)));
    }


    // Let us walk through the child elements now.
    foreach($simpleXmlElementObject as $key=>$value) {
      // When this block of code is commented, XML attributes will be
      // added to the result array.
      // Uncomment the following block of code if XML attributes are 
      // NOT required to be returned as part of the result array. 
      /*
if((is_string($key)) & ($key == SIMPLE_XML_ELEMENT_OBJECT_PROPERTY_FOR_ATTRIBUTES)) {
        continue;
      }
      */


      // Let us recursively process the current element we just visited.
      // Increase the recursion depth by one.
      $recursionDepth++; 
      $resultArray[$key] = 
        xml2json::convertSimpleXmlElementObjectIntoArray($value, $recursionDepth);


      // Decrease the recursion depth by one.
      $recursionDepth--;
    } // End of foreach($simpleXmlElementObject as $key=>$value) { 


    if ($recursionDepth == 0) {
      // That is it. We are heading to the exit now.
      // Set the XML root element name as the root [top-level] key of
      // the associative array that we are going to return to the caller of this
      // recursive function.
      $tempArray = $resultArray;
      $resultArray = array();
      $resultArray[$callerProvidedSimpleXmlElementObject->getName()] = $tempArray;
    }


    return ($resultArray);
  } else {
    // We are now looking at either the XML attribute text or
    // the text between the XML tags.
    return (trim(strval($simpleXmlElementObject)));
  } // End of else
} // End of function convertSimpleXmlElementObjectIntoArray.

<?php
    require_once("xml2json.php");


    // Filename from where XML contents are to be read.
    $testXmlFile = ";


    // Read the filename from the command line.
    if ($argc <= 1) {
        print("Please provide the XML filename as a command-line argument:\n");
        print("\tphp -f xml2json_test.php test1.xml\n");
        return;
    } else {
        $testXmlFile = $argv[1];
    }


    //Read the XML contents from the input file.
    file_exists($testXmlFile) or die('Could not find file ' . $testXmlFile);
    $xmlStringContents = file_get_contents($testXmlFile);


    $jsonContents = ";
    // Convert it to JSON now.
    // xml2json simply takes a String containing XML contents as input.
    $jsonContents = xml2json::transformXmlStringToJson($xmlStringContents);


    echo("JSON formatted output generated by xml2json:\n\n");
    echo($jsonContents);
?>

php -f xml2json_test.php test2.xml

<?xml version="1.0" encoding="UTF-8"?>
<books>
    <book id="1">
        <title>Code Generation in Action</title>
        <author><first>Jack</first><last>Herrington</last></author>
        <publisher>Manning</publisher>
    </book>


    <book id="2">
        <title>PHP Hacks</title>
        <author><first>Jack</first><last>Herrington</last></author>
        <publisher>O'Reilly</publisher>
    </book>


    <book id="3">
        <title>Podcasting Hacks</title>
        <author><first>Jack</first><last>Herrington</last></author>
        <publisher>O'Reilly</publisher>
    </book>
</books>

{
   "books" : {
      "book" : [ {
         "@attributes" : {
            "id" : "1"
         }, 
         "title" : "Code Generation in Action", 
         "author" : {
            "first" : "Jack", "last" : "Herrington"
         }, 
         "publisher" : "Manning"
      }, {
         "@attributes" : {
            "id" : "2"
         }, 
         "title" : "PHP Hacks", "author" : {
            "first" : "Jack", "last" : "Herrington"
         }, 
         "publisher" : "O'Reilly"
      }, {
         "@attributes" : {
            "id" : "3"
         }, 
         "title" : "Podcasting Hacks", "author" : {
            "first" : "Jack", "last" : "Herrington"
         }, 
         "publisher" : "O'Reilly"
      }
   ]}
}