Following post states that: http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.webcontrols.spappiframe.aspx
SPAppIframe supports postmessage communications that lets the iframed content send a resize message to the parent page to resize the iframe.
Postmessage communications between the iframed content and the parent page is only possible in server side code? If yes, then how to do it? If not, then how to take advantage of this in CSOM or javascript?
Is it possible to send communication from the parent page to the iframed content? [One possibility that I see doing this one is to have send the message to the iframed content is by passing query parameters in the src url of the iframe and accordingly parse/ act on it thru client script or server code in the particular page or master page]
Thanks Arut