In 7.3.1+ you can create a Data Transform with "Data model format" (under "Additional configuration options") to 'JSON'.

The simplest case; you can just set 'Auto-map all date' - keeping the "top element structure" as "Object".

That's it; the incoming JSON (so long as it 'fits') - will get mapped to the named properties.

(In fact, the properties don't actually have to exist to demonstrate the Data Transform working - but you'll want to create them in real life).

You then call the DT with two PARAMs:

jsonData
executionMode

Set 'executionMode' to "DESERIALIZE"; set the jsonData to the full string of the JSON.

[ NOTE: I had to change your JSON - the leading "." (dot) doesn't work - since (I presume) that is ambiguous for the PRPC expression language - where the "." prefix is used when deferencing Properties; basically you are not allowed property names that start with a "." (dot) ]

So your modified JSON looks like this:

{"Name": "John","LastName": "Doe","BirthDate": "2017-05-24 14:25:05"}

And the result page looks like this:

<?xml version="1.0"?>

<pagedata>
<pxObjClass/>
<LastName>Doe</LastName>
<Name>John</Name>
<BirthDate>2017-05-24 14:25:05</BirthDate>
<pzStatus>valid</pzStatus>
</pagedata>

Here's my DT (check the PARAMs tab as well):

Here's my test Activity showing how to call the DT: