Parse SOAP with multiple namespaces request in PHP

Question

I have an endpoint that will receive a SOAP message in request. The structure of the Soap message is as below.

<soap-env:Envelope
    xmlns:soap-env="http://schemas.xmlsoap.org/soap/envelope/">
    <soap-env:Header
        xmlns:soap-env="http://schemas.xmlsoap.org/soap/envelope/">
        <wsse:Security
            xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
            xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" soap:mustunderstand="1">
            <wsse:UsernameToken>
                <wsse:Username>username</wsse:Username>
                <wsse:Password type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#passwordtext">secret</wsse:Password>
            </wsse:UsernameToken>
        </wsse:Security>
    </soap-env:Header>
    <soap-env:Body
        xmlns:soap-env="http://schemas.xmlsoap.org/soap/envelope/">
        <OTA_HotelResNotifRQ
            xmlns="http://www.opentravel.org/OTA/2003/05" Version="1.0" EchoToken="4528545b-f875-5c77-9205-22631b68f15a" ResStatus="Commit" TimeStamp="2018-07-31T01:16:16Z">
            ...
        </OTA_HotelResNotifRQ>
    </soap-env:Body>
</soap-env:Envelope>

I am trying to find a way to convert this into a array or a json. When i am using simplexml_load_string and json_ecode it it returns an empty array.

I am able to access to XML by registering the name spaces but is there a way to convert the above soap message into array or Json that can be accessed easily?