Monday, April 30, 2007

wrapping up http caching

after pouring over the http 1.1 docs and a number of other articles and books, i'm pretty sure i have the basic caching pattern down:


to reduce traffic, use expiration caching (expires for 1.0 and cache-control for 1.1) to tell public caches to serve requests without talking to the origin server.

to reduce bandwidth, use validation caching (last-modified for 1.0 and etags for 1.1) to tell public caches to use conditional gets to the origin server who can return a 304 instead of returning a full copy of the resource.

so this is all cool. i have this built into the ws-loop now. if you are doing a GET and the class generating the resource has max-age, etags, and/or last-modified set, caching headers will be sent with the response. and whenever a class is handling a GET, it will check for if-not-modified and if-none-match and return 304 if the resource has not changed.


so that's the public side of things. under the hood, the ws-loop is creating a local copy (on disk) of the requested resource and using that to serve up to clients as long as the file-date is not stale (based on max-age).  so, while the class still has to respond (no direct file delivery here), it will still deliver a disk copy of the resource for as long as it is directed. that's cool.


now the only other item that could be intersting would be gzip and deflate.  i need to look into how to implement that for dynamic resources (when supported) using the .net 2.0 compression classes.


once that's done, i have some housekeeping to do with the ws-loop. cleaning up naming, some constants, implementing the ws-loop at the server root using isapi rewriter, etc.

once the clean up is done, some other niceties like moving the user/auth work into the db instead of xml and maybe making caching an external config insteado code work would be good. then it's back to building REST-ian apps in general.

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