Parsing XML with PHP - php

Question

I know taht there already are many question about this subject but I haven't find the solution for my problem.
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<soap:Header>
<PeopleCountingServiceHeader xmlns="http://localhost/countingws/">
<Username>username</Username>
<Password>password</Password>
<Camera>essai</Camera>
</PeopleCountingServiceHeader>
</soap:Header>
<soap:Body>
<InsertData xmlns="http://ai-sense.com/counting/">
<impacts>
<Impact>
<TimeStamp>2014-10-23T15:17:51.879</TimeStamp>
<Type>Output</Type>
<Layer>0</Layer>
</Impact>
<Impact>
<TimeStamp>2014-10-23T15:17:52.753</TimeStamp>
<Type>Input</Type>
<Layer>0</Layer>
</Impact>
<Impact>
<TimeStamp>2014-10-23T15:17:54.375</TimeStamp>
<Type>Output</Type>
<Layer>0</Layer>
</Impact>
<Impact>
<TimeStamp>2014-10-23T15:17:55.186</TimeStamp>
<Type>Input</Type>
<Layer>0</Layer>
</Impact>
<Impact>
<TimeStamp>2014-10-23T15:18:28.897</TimeStamp>
<Type>Output</Type>
<Layer>0</Layer>
</Impact>
<Impact>
<TimeStamp>2014-10-23T15:18:29.771</TimeStamp>
<Type>Input</Type>
<Layer>0</Layer>
</Impact>
<Impact>
<TimeStamp>2014-10-23T15:22:41.219</TimeStamp>
<Type>Output</Type>
<Layer>0</Layer>
</Impact>
</impacts>
</InsertData>
</soap:Body>
</soap:Envelope>
And I want to retrieve for example the username.
I have already try somethinf like this :
$request =simplexml_load_file("php://input", NULL, TRUE);
echo "request: "$request->{"soap:Header"}->PeopleCountingServiceHeader->Username;
How can I access to my datas ?

Answer 1

This is not just XML, but SOAP. PHP has a specific extension for it: ext/soap.
SOAP is an XML format to transfer objects between systems. You could parse it manually, but a specific SOAP implementation is a lot more convenient.
If you parse in manually you have to consider the namespaces. Here are 3 namespaces in your example XML:
http://schemas.xmlsoap.org/soap/envelope/ - the SOAP envelope, using a soap prefix/alias
http://localhost/countingws/ - elements inside soap:Header, no prefix/alias
http://ai-sense.com/counting/ - elements inside soap:Body, no prefix/alias