Generating Dynamic SSML from "HTTP Request" to be used on a "Get Input" - plivo

Question

I'm wondering if anyone can be of assistance.
I am trying to generate some dynamic Amazon Polly SSML to be used on the Plivo PHLO platform. When someone dials into a particular number, they should be greeted with a custom message (in a particular language) and prompted to enter a number.
I have an HTTP request that hits my API, which receives the request and generates the SSML using Plivo's PHP Server SDK.
$response = new Response();
$speak_elem = $response->addSpeak($result['text'], ['language'=> 'en-US, 'voice'=>"Polly.Joanna"]);
Header('Content-type: text/xml');
die( $response->toXML() );
It seems to me that this HTTP Request is working perfectly and returning perfect SSML. When I copy and hard-code-paste the SSML into the Get Input node, it works OK.
<?xml version="1.0" encoding="utf-8"?>
<Response><Speak language="en-US" voice="Polly.Joanna">Welcome To 101 Broadway. For English, press 1.</Speak></Response>
However, when I try to add a Get Input component and link it's "prompt" audio to the resulting SSML, I am getting an error that says Invalid SSML (See Screenshots at the bottom).
WHAT I'VE TRIED
I've tried returning the SSML in plain XML and using {{HTTP_Welcome.response}}
I've tried returning the SSML as text in a JSON object called SSML and using {{HTTP_Welcome.response.SSML}}
I've tried returning the SSML both with and without the xml tag.
I've tried returning the SSML both with and without the Result tag.
I've tried taking a break and coming back to it. Hey, you never know.
No matter how I return the SSML, and how I try to link it to the Get Input prompt, I am unsuccessful. I'm starting to wonder if this is even possible?
Any help would be immensely appreciated. Thanks!
SCREENSHOT 1
SCREENSHOT 2

Answer 1

My name is Mohammed Huzaif, and I work for Plivo as a Developer Evangelist.
Unfortunately, the "GetInput node" in PHLO does not yet implement the feature you are searching for. The best option is to use a standard speak which is customisable in your way, which may have a less natural feel than SSML.
Currently, I've narrow information about your use case as of now but If you still want to use a custom SSML, I'd recommend utilising a framework instead of PHLO to design your call flow. Here's a tutorial that covers a few use cases by Plivo in several frameworks to help you develop one.
If you experience any problems, please feel free to contact our support team.