Hi. I need to debate web map images caching technique. I'm using OpenLayers with tiled mapserver layer. But now I dissatisfied mapserver image request url scheme because it has variable map config file name (path) as a part (parameter), and some may be some other variable parts (for ex. OL use random '_olSalt' parameter to force HTTPRequest layer map redraw, time stamps, session id's etc.). I decide to change this scheme to have constant url for map image tile of the same bbox (extent), config & data 'stamps' to support browser caching. Map file can be constant but not in 'true' multiuser environment where they are customized for each user needs, according their rights (privileges). So map file name vary often by session (id) indirectly. We can exclude other url variables painlessly. Final tasks: - overwraiting some OL code to build correct url - create http handler to wrap mapserver cgi (and may be support intranet clusterization) - but how to provide some hash key for mapserver (all layers/styles...) config and data 'stamps'. Currently (for test purpose) I use CRC32 of map SLD as this hash. I can support versioning with some 'seed' metadata in map file for config and/or in (spatial-) database for data (for each layer in service table 'data_version'). Seed (version info) will be changed (by some way) after each 'publishing operation'. May be another way exists (other comprehensive map object string serialization/dumping to calculate checksum from it, some wms/wfs command)?
-- View this message in context: http://n2.nabble.com/Need-advice-to-support-caching-mechanism-tp2484552p2484552.html Sent from the Mapserver - User mailing list archive at Nabble.com. _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users
