Hi Jon, On Wed, Feb 17, 2010 at 11:37 PM, Jon Burgess <jburgess...@googlemail.com> wrote: >> But if you try on the OSM server, then it works correctly: no tile is >> sent by the server if viking already has a recent tile. > > Do you mean that the osmarender server works as you expect here?
Exactly - I meant that the osmarender server accepts the If-Modified-Since header, and returns 304 if the server file is older or the same date than the client file. > When the client makes a request it should store the ETag returned. When > it comes to request the tile again the client includes this ETag in a > If-None-Match header. If the current tile on the server still has the > same content then this will trigger a 304/NotModified response. I have > included an example of in an attachment. > > We also return "Expires:" and "Cache-Control:" headers which can assist > the client in deciding when to try requesting the tile again. > > All these headers are defined in the various HTTP RFCs. In theory, > properly written web browsers and caches should work fine with them but > I am beginning to wonder whether I should discard the ETag and move back > to a simple last-modified time system. Thanks for the explanation. Guilhem is right in pointing that the client will need to store the ETag value as a metadata, which makes ETag support not as easy to implement as last-modified. Do you know if any software uses ETag with tile.openstreetmap.org ? I will look tonight if it is simple to use ETag with viking and libcurl - it should only be a matter of adding "file.etag" alongside the image file. Thanks, Jocelyn ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Viking-devel mailing list Viking-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/viking-devel Viking home page: http://viking.sf.net/
