问题
I'm reading through details on HTML5's app cache manifest (especially from this excellent article). I'm curious if this idea would work:
We host all of our static resources (scripts, css, fonts, images) on a CDN within a subdomain (e.g. cdn.example.com and app is on www.example.com). Is it possible to host the app cache manifest on the CDN as well? For example,
<!doctype html>
<html manifest="http://cdn.example.com/appcache.manifest">
...
<script src="http://cdn.example.com/foo.js"></script>
...
</html>
If yes, can the manifest listings be from the CDN root? For example, in the manifest:
CACHE MANIFEST
/foo.js
Does anyone have any experience with this and/or know of any caveats?
EDIT: The working draft of the WHATWG spec it says "Offline application cache manifests can use absolute paths or even absolute URLs" and then shows an example with CDN URLs for images.
回答1:
I tested with my manifest (in real example)
CACHE MANIFEST
# 2010-06-20:v1
iscroll.js
http://peach.blender.org/wp-content/uploads/big_big_buck_bunny.jpg
It works to me... You can check you manifest with validator http://manifest-validator.com/.
W3C only says the document (HTML file that have manifest attribute) must be same origin source with the manifest, they don't tell URL of resources must be too... You should read it carefully (at here). I also found the cross-site URL in W3 example (check here), that means it works correctly...
Finally, DON'T TRY TO PUT MANIFEST FILES ON CDN, JUST PUT IT IN YOUR SERVER AND LINK RESOURCE TO CDN. Manifest files have to have the same origin as their master entries, which includes their HTML files, and the browser checks the manifest file to see if its list of HTML pages has changed, rather than checking your HTML page to see if it points to a different manifest file.
回答2:
The cached contents must satisfy the same origin restriction and the origin for comparison is determined by the calling page (the HTML page). If all of the resources you are trying to cache have a different host name then according to the spec they should be rejected. So even if you could specify the manifest to be on the cdn and not your main host, the caching should fail.
来源：https://stackoverflow.com/questions/7479319/app-cache-manifest-on-cdn