URL iviews are not cached in client browser!!!

Question

Hi All,
We have URL ivews of ASP.NET pages in our Portal Home page.
Those ASP.NET pages are located in MS Windows Server (IIS).
It takes long time to load the Portal Home page.
We set the Allow Client-Side Caching - Yes, Cache Level - Shared, Cache
Validtiy Period: 7.59.59 for all URL iviews.
For the Home page which contains all URL iviews Isolation Method
property is set to Embedded.
We set "Enable Content Expiration" - 8 Hours for the "Root - virtual
directory" in IIS.
When I browse those pages with the URL directly in IE (outside Portal).
It runs faster and returns with HTTP status code "cached".
All the pages including HTML are cached in client browser.
When I logged into portal all images, css and javascript files are
cached in the client browser but not the HTML content. It returns with
HTTP status code 200 whick means URL iviews are not cached in client browser.
Thanks
Thruna Shanmuga

Answer 1

Hi Thruna,
The only header which influences caching behaviour in your request is the 'Cache-Control: private' header, which afaik means that the page cannot be cached by a shared cache (such as a web proxy), but can be cached in a personal proxy such as the browser cache.
However the headers do not specify a specific expiration date which means that the browser cannot know how long the response can be cached and thus has to check validity every browser session. The most optimistic scenario would be that the browser checks if the cached entry is still valid by requesting the resource and adding a If-Modified-Since or If-None-Match header. The server could then respond with a 304 Not Modified, skipping sending the actual resource in the response body.
If you want the resource to be fully cached you have to give it an expiration date in the future. This has to be done in the IIS server, maybe through ASP tags in the page.
I do not know why the page is loading from cache in the non-portal scenario but I can only suggest that you make absolutely sure the cache item was not validated already in the session.
With kind regards,
Thijs Janssen