A question about DIAL REST Service: Application launch process

[warner0721]

Dear Sirs,

We are trying to implement the application launch process in DIAL-2ndScreenProtocol-2.1, ch 6.3.

The DIAL 2.1 spec only said that "If a first-screen application receives an ​additionalDataUrl, the application should POST a request to that URL as soon as the additional data is available."
We want to know how to deal with the situation when the DIAL client sends a GET request (step 7) before the first-screen application sends a POST request (step 6)?
Should one of the following rule be applied?

1. The DIAL client has no guarantee to obtain additionalData in GET response (step 8)
2. Add time limitations between the first-screen application receives a launch request (step 4) and responses a POST request (step 6), and between the dial client receives a POST response (step 5) and sends a GET request (step 7).

I'm not sure if it is suitable to ask the question. If not, could you please tell me where is suitable to ask the question?
Thanks for your kind reply.

BRs,
Warner