James E. Robinson, III: Bob Wyman suggested i implement RFC3229 to make proxies and caches behave nicely with sending only modified content. The new wp-rss2.php file does just that.
In addition to the lack of Apache support that James mentions, I see three problems:
- If the bloginfo changes, it will never be resent.
- The client is responsible for remembering the original encoding, which again, hopefully never changes.
- Few platforms (actually, none that I know of) have support for parsing XML fragments (sets of elements).
The second issue could be mitigated by adding the charset to the Content-Type header, something that should be done anyway.
The second and third issues could be addressed by clients which retain a full copy, byte for byte, of the data that they originally received from the server. Such implementations would be faced with ever increasing storage requirements as this implementation never deletes any data.
At the moment, I still prefer solutions involving hashes of the complete data, and complete XML documents.