Redirect from Activity post to specific canvas (iframe) page [duplicate] - facebook

Question

I am embedding a Facebook app https://example.com into the Facebook app canvas so that it is available at https://apps.facebook.com/EXAMPLE . My application sends notification emails that contain links like https://example.com/messages/123 and that should open the page embedded into the Facebook canvas. How do I achieve this? My current thoughts:
User opens https://example.com/messages/123
Application checks for signed_request parameter
Application redirects user to https://apps.facebook.com/EXAMPLE/?requested_page=/messages/123
Application checks for requested_page parameter and redirects to this page
User sees https://example.com/messages/123 URL and is embedded into canvas
Is there a better pattern out there to get this working?
My final working solution (with Ruby on Rails)
User opens https://example.com/messages/123
Application checks on client-side if app is embedded in canvas:
if(window == top){
top.location = "https://apps.facebook.com/#{Settings.facebook.app_id}#{request.fullpath}";
}
User is redirected to https://apps.facebook.com/EXAMPLE/messages/123
Application middleware converts POST into GET if signed_request is present (code and idea borrowed from https://github.com/dekart/facebooker2/blob/master/lib/facebooker2/rack/post_canvas.rb)
Application parses signed_request with fb_graph gem
FbGraph::Auth.new(app_id, app_secret, :signed_request => params[:signed_request])

Answer 1

I'd just update the link to point to http://apps.facebook/example/messages/123 off the start.
When you check for authentication just set the redirect after authorization/login to the same page.
Redirecting a user around multiple pages for no reason is just not a good practice.