We have made some updates to the Memento extension and we have also written a fix to perform datetime content negotiation on transcluded templates. Details can be found in the wiki page for the extension http://www.mediawiki.org/wiki/Extension:Memento . Harihar (Los Alamos National Labs)
Herbert Van de Sompel wrote: > On Nov 12, 2009, at 3:19 PM, Platonides wrote: > >>> 2.6. The caching issue is a general problem arising from introducing >>> Memento in a web that does not (yet) do Memento: when in datetime >>> content negotiation mode all caches between client and server (both >>> included) need to be bypassed. As described in our paper, we >>> currently >>> address this problem by adding the following client headers: >>> >>> Cache-Control: no-cache => to force cache revalidation, and >>> If-Modified-Since: Thu, 01 Jan 1970 00:00:00 GMT' to enforce >>> validation failure >>> >>> We very much understand this is not elegant but it tends to >>> work ;-) . >>> >> The caching issue is IMHO the bigger problem in your approach using >> the >> new header. >> Disabling cache on the request kind of work (although not in the long >> term), but you also need to disable caching at the server, so when >> someone accessing by your same proxy (ignorant of X-Accept-Datetime) >> to >> the current page doesn't get the cached page you were served earlier. >> > > Agreed, of course, that our current cache fix is a temp solution. > > Not sure what you mean by the above remark, but it is totally fine to > cache the current page in mediawiki because the history pages are not > served from the URI of the current page, neither by our plug-in nor in > Memento in general (see http://www.mementoweb.org/guide/http/local/). > Rather, a X-Datetime-Accept request is redirected (302 Found) to an > appropriate history resource that has its own URI (with title and > oldid in case of mediawiki). And, hence, even those history pages can > be cached by mediawiki equipped with the memento plug-in. > > >> RFC 2145 states very clearly that "A proxy MUST forward an unknown >> header", but in your case it'd have been preferable that the header >> wasn't forwarded if the proxy isn't memento aware. >> >> Which leads us to another issue, which is that it seems your server >> implementation doesn't "acknowledge" memento, so given a response to a >> X-Accept-Datetime, you don't know if what you're getting is the >> version >> you requested or the current one (because the server ignored it). >> It can be as simple as requiring a Last-Modified <= X-Accept- >> Datetime on >> Accept-Datetime responses (that would allow the server to explicitely >> tell since when is it valid), but extended to all response codes. >> >> > > > Actually, have a look at http://www.mementoweb.org/guide/http/local/ . > You will note that the following response header is always included: > > X-Archive-Interval: {datetime_start} - {datetime_end} > > This allows a client to understand he received a history resource. The > values to use are the start datetime and end datetime for which the > server has representations for the the URI at hand. > > Our plug-in implements this for mediawiki. Our proxy can't do this. > > Cheers > > herbert > > > == > Herbert Van de Sompel > Digital Library Research & Prototyping > Los Alamos National Laboratory, Research Library > http://public.lanl.gov/herbertv/ > tel. +1 505 667 1267 > > > > > > _______________________________________________ > Wikitech-l mailing list > Wikitech-l@lists.wikimedia.org > https://lists.wikimedia.org/mailman/listinfo/wikitech-l > _______________________________________________ Wikitech-l mailing list Wikitech-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikitech-l
