Implement XD transport based on JSONPI: yes Virginia, it is possible!

[MaxMotovilov]

Use JSONPI approach as outlined by Ben Vinegar on TxJS 2011 to implement limited XD capability:

Sendng request:

document.domain = "toplevel.com"; // Have to be on subdomain1.toplevel.com or won't work!

(iframe name="jsonpi_target")

(form target="jsonpi_target" method="{desired HTTP verb}" action="{XD-url on subdomain2.toplevel.com}")
  (input type="hidden" name="body" value="{PUT or POST body}")
(/form)

Sending response:

(script)
  document.domain = "toplevel.com"; // Have to be on subdomain2.toplevel.com or won't work!
  getJSONPICallback( key_url_params, window.parent )( {Response body} );
(/script)

Optimally, the implementation should use a Dojo transport for JSONPI which is yet to be implemented...