How to get json data from a REST API call?

Something like this:

 

Function TestHttps() as Dynamic
    print "HTTPS STARTED"
    
    url = " ... enter url "
    timeout = 1500
    num_retries = 1
    
    http = CreateObject("roUrlTransfer")
    port = CreateObject("roMessagePort")
    
    http.SetUrl(url)
    http.SetMessagePort(port)
    http.SetRequest("POST")
    http.AddHeader("Content-Type", "application/json")
    http.AddHeader("X-Roku-Reserved-Dev-Id")
    http.SetCertificatesFile("pkg:/source/certificates/cafile.pem")
    http.EnableHostVerification(true)
    http.EnablePeerVerification(true)
    http.InitClientCertificates()
    http.RetainBodyOnError(true)
    
    while num_retries > 0
        if (http.AsyncPostFromString(""))
            event = wait(timeout, http.GetPort())
            print event
            if type(event) = "roUrlEvent"
                dd =  event.GetString()
                code = event.GetResponseCode()
                print code
                if code = 200
                    print "HTTPS data:" + dd
                    print "HTTPS code:" + ToString(code)
                    return dd
                else
                    print "HTTPS data:" + dd
                    print "HTTPS code:" + ToString(code)
                    timeout = timeout * 2
                    num_retries = num_retries - 1
                    print "HTTPS New try: " + ToString(num_retries)
                endif
            else
                timeout = timeout * 2
                num_retries = num_retries - 1
                print "HTTPS New try: " + ToString(num_retries)
            endif
        endif
    end while
    print "HTTPS FINISHED"
End Function

http.SetCertificatesFile("pkg:/source/certificates/cafile.pem")

It needed if you have ca certificate file that makes domain trusted from untrusted, otherwise

http.SetCertificatesFile ("common:/certs/ca-bundle.crt")

If all will be good: code will be 200 and data will be in correct format (valid json), then need continue to thinking