[dev] prefetching

[Amith Varghese]

> mozilla now has prefetching,
> http://www.mozilla.org/projects/netlib/Link_Prefetching_FAQ.html
> 
> how about adding this to imp for new messages in the mailbox? they are almost
> certainly going to be opened, so might as well let mozilla cache them during
> its
> idling.
> 
> other apps?

This is also interesting to note.  I think its use is limited considering how 
Horde/IMP work.

Amith

Are there any restrictions on what is prefetched?
Yes, only http:// URLs can be prefetched (https:// URLs are never prefetched 
for security reasons).  Other protocols (such as FTP) do not provide rich 
enough support for client side caching.  In addition to this restriction, URLs 
with a query string are not prefetched.  This is done because such URLs often 
result in documents that cannot be reused out of the browser's cache, so 
prefetching them often has little benefit.  We found that some existing sites 
utilize the <link rel="next"> tag with URLs containing query strings to 
reference the next document in a series of documents.  Bugzilla is an example 
of such a site that does this, and it turns out that the Bugzilla bug reports 
are not cachable, so prefetching these URLs would nearly double the load on 
poor Bugzilla!  It's easy to imagine other sites being designed like Bugzilla, 
so we explicitly do not prefetch URLs with query strings.  (It might make sense 
to allow prefetching of these documents when the rel=prefetchrelation type is 
specified, since this should not appear in any existing content.)  There are no 
other restrictions on the URLs that are prefetched