I created a small and very simple REST-based webservice with PHP. This service gets data from a different server and returns the result. It's more like a proxy rather than a full service.
Client --(REST call)--> PHP Webservice --(Relay call)--> Remote server
<-- Return data ---
In order to keep costs as low as possible I want to implement a caching table on the PHP webservice system by maintaining data for a period of time in server memory and only re-request the data after a timeout (let's say after 30 mins).
In pseudo-code I basically want to do this:
$id = $_GET["id"];
$result = null;
if (isInCache($id) && !cacheExpired($id, 30)){
$result = getFromCache($id);
}
else{
$result = getDataFromRemoteServer($id);
saveToCache($result);
}
printData($result);
The code above should get data from a remote server which is identified by an id. If it is in the cache and 30 mins have not passed yet the data should be read from the cache and returned as a result of the webservice call. If not, the remote server should be queried.
While thinking on how to do this I realized 2 important aspects:
- I don't want to use filesystem I/O operation because of performance concerns. Instead, I want to keep the cache in memory. So, no MySQL or local file operations.
- I can't use sessions because the cached data must be shared across different users, browsers and internet connections worldwide.
So, if I could somehow share objects in memory between multiple GET requests, I would be able to implement this caching system pretty easily I think.
But how could I do that?
Edit: I forgot to mention that I cannot install any modules on that PHP server. It's a pure "webhosting-only" service.