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Forward Proxy > Static vs. Dynamic Content > Deciding What to Cache

Reverse Proxy

The diagram below depicts the operation of SpiderCache in reverse proxy mode.  Here’s how it works. SpiderCache ‘watches’ data traffic flowing to and from the web server, and takes action on the basis of what it sees.  If it sees a request that it hasn’t seen before(1), it passes that request on to the web server(2), which fulfills the request in the usual fashion.  As the request is fulfilled(3), Warp’s caching engine makes a copy of the data served by the web server and stores it locally, before forwarding the data to the requesting user (4). 

SpiderCache in Reverse Proxy Mode

The next time an identical request is seen, the cache intercepts the request and fulfills the response directly from the stored data in the cache, without needing to consult the web server, and the response time to the requesting user is cut dramatically (1,4).  The first user to request the data, then, sees no improvement, but every subsequent user benefits from much faster response times.

Caching of this type is exceptionally elegant because it is heuristic – that is, the caching engine learns what to cache, and when, from its own operation.  It is thus a precise reflection of the environment that it serves, and is therefore extremely efficient.

Refreshing the Cache

This all happens in real time, and is completely invisible both to the requesting user and the web server.  The trick is in knowing when to ask the web server for new data.  If the request is new, there is no difficulty – the request is passed through as described above.  But – and it’s a big ‘but’ – if the request is for data that has already been cached, the cache must decide if the cached copy of the data is still identical to the data housed in the web server before intercepting the request.  This is critical – one does not want to serve inaccurate data (to a stock broker who’s just requested the stock price of, say, Warp Solutions, Inc. prior to executing a trade for 100,000 shares).  It’s bad form.

Warp solves this problem with the a sophisticated, parameterized series of algorithms that assess the accuracy of in-cache data, and inform the cache if a data “refresh” is necessary.  Data that needs refreshing is simply retrieved again from the web server and stored locally, replacing the previous copy.  Warp’s cache refresh technology is easily the most powerful, sophisticated, and flexible technology of it’s kind, and is the most salient reason why Warp Solutions leads the industry in caching technology.