Home/ Questions/Q 3274566
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-17T19:03:09+00:00

I’d love to stash some .json files on a CDN a la static.mydomain.com. Truth

  • 0

I’d love to stash some .json files on a CDN a la static.mydomain.com. Truth be told, static.mydomain.com is a CNAME in front of an Amazon S3 bucket.

I understand this violates the JavaScript security model. Is there an advised workaround or design? I’ve seen server-side stuff suggested like a PHP script to suck down data via cURL or file_gets_contents(), but that’s a pretty lame approach. Is there any way to load JSON from a foreign server without getting too hacky?

===

UPDATE: Here’s the line of thought that led me to believe it’s a crossdomain issue for subdomains.

When I visit a page (e.g. static.mydomain.com/json/file.json) in Chrome, it displays as it would plaintext. When I visit the page in Firefox, it tries to get me to save the .json as a download.

I see a peculiar result in Firebug: A 200 response with no response body. alt text

I can’t log the direct headers via browser; my Firefox HTTP header plugin doesn’t log anything before the download is forced. However here are the headers when loaded via this jQuery snippit (worth noting, the alert below doesn’t fire):

jQuery.get("https://static.mydomain.com/json/file.json",
   function(data){
     alert("Data: " + data);
   }
);

Response Headers

x-amz-id-2 wSVtjlvFj5ffOtg7ZbKqKw8PexqlzJic7+PxSk975/FcDUnshSV2CiUP2oPWR8yK
x-amz-request-id 8AD81565A783988D
Date Tue, 19 Oct 2010 00:07:22 GMT
Expires Sat, 17 Oct 2015 22:25:37 GMT
Last-Modified Mon, 18 Oct 2010 01:08:13 GMT
Etag "2f1c7adcc1a7b0fd8fc8ce1478e0bf81"
Content-Type application/json
Content-Length 85966
Server AmazonS3

Request Headers

Host static.mydomain.com
User-Agent Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.8) Gecko/20100722 Firefox/3.6.8
Accept application/json, text/javascript, */*; q=0.01
Accept-Language en-us,en;q=0.5
Accept-Encoding gzip,deflate
Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive 115
Connection keep-alive
Referer http://mydomain.com/directory/referrer.html
Origin http://mydomain.com

Though the headers seem to me to be fine, there is no response body to either a get, post, or anything else I can throw at this via jQuery. I see the same result when setting the content type to application/json, text/javascript and text/plain.

Can anyone explain this behavior? I figure I must be doing something wrong on the S3 side, but could it be crossdomain issues in JavaScript or can I rule out cross-subdomain issues?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Use jQuery.getJSON instead of .get. .get uses an XHR, which is not friendly across domains (even subdomains). getJSON uses a JSONP request which will work.

    http://api.jquery.com/jQuery.getJSON/

    You’ll need to modify the JSON data for a JSONP response though. It takes a parameter that defines a callback. jQuery creates a random function to serve as the callback, so if your whole point is to use this as a CDN, you don’t be able to dynamically change the callback name in the response.

    You can use a static callback by passing the right parameters to jQuery.ajax:
    http://api.jquery.com/jQuery.ajax/

    dataType: 'json' //(.getJSON is just a shorthand for .ajax with this paraeter set)
jsonpCallback: 'myStaticCallbackName' // Lets the client know what callback to expect from the server.

    Then your response should look like:

    myStaticCallbackName({"foo": "bar"});
    • 0