JSR 286 Validation caching

Hi

As per teh new specification, the ETag can be set on the response. I have a couple of doubts here:

1. The ETag is in the http header. However, when i implemented a sammple JSR 286 portlet, there was no caching infomation in the page rendered, although the caching was working fine. Why is there no cachhing header in the page html

2. The ETag is a page header. Then how can we set it on a portlet as portlet is just a fragment of markup wheres ETag is a page header?

3. In case of caching for dynamically served resources, where will teh resources be cached - on server or on client? If it is on server, then which server is it going to be? Having it on the portal server does not make much sense to me since these are dynamic resources. Are these on the app server then?

4. I read a blog at this URL: http://www.improve.dk/blog/2009/03/08/resource-urls-and-their-effect-on-client-side-caching. We are talking about ETag in the spec. Then why is this dynamic URL thing required as this obviates the need for having an ETag

Thanks