Adding htmlentities() can be helpful since it makes the XML visible in your browser without needing to view the source.

<?php

echo "REQUEST:\n" . htmlentities($client->__getLastRequest()) . "\n";

?>

Note that when you create SoapClient with option "trace" set to FALSE or omit it, than "__getLastRequest()" always returns NULL.

I guess many peoples calls getLastRequest and it returns nothing. "Heey where is the my last request". Now we will see our request,  when you created a SoapClient instance, you should give a option parameter as below :

<?php
// below $option=array('trace',1);
// correct one is below
$option=array('trace'=>1);

$client=new SoapClient('some.wsdl',$option);

try{
  $client->aMethodAtRemote();
}catch(SoapFault $fault){
  // <xmp> tag displays xml output in html
  echo 'Request : <br/><xmp>',
  $client->__getLastRequest(),
  '</xmp><br/><br/> Error Message : <br/>',
  $fault->getMessage();
}
?>

"trace" parameter enables output of request. Now, you should see SOAP request.

Just to make it a bit more readable

echo "REQUEST:\n" . htmlentities(str_ireplace('><', ">\n<", $client->__getLastRequest())) . "\n";
echo "Response:\n" . htmlentities(str_ireplace('><', ">\n<", $client->__getLastResponse())) . "\n";

PS: If you are using \n then you need to enclose above statements in <pre>. You can also use <br />, but it gets a bit messy.

Creating an xml file and link to the file is my way.

$outputxml = '/output.xml';

file_put_contents($_SERVER['DOCUMENT_ROOT'] . $outputxml, $client->__getLastRequest());

echo '<a href="' . $outputxml . '">here</a>';