Cache

A cache is a temporary storage area where data that is accessed constantly can be stored for quick access. The caching feature of the Plum IVR operates like a proxy cache. However, for on-site Plum IVR systems, this caching feature must be enabled or else nothing will be cached.

When a file is requested from the proxy cache, the proxy cache first checks to see whether the file is currently stored locally. If the file is currently stored locally, it then checks when the local copy of the file is set to expire. If the local copy has not expired, it is immediately sent back to the platform. If the local copy has expired, the proxy cache requests only the status of the file from the source site. If the source copy has not been changed, the local copy of the file is sent back to the platform. If the source copy has been changed, the proxy requests the contents of the file from the source site and refreshes the local copy.

The Plum caching system follows standard proxy caching rules. The behavior of the proxy cache can be modified in two ways. First, the maxage attribute of any of the tags that make web requests can be set to a number of seconds that will override the expiration time for the local copy of the file. If, for instance, maxage is set to "0", the proxy cache will always check the status of the file from the source site.

Second, the maxstale attribute can be set to a number of seconds to extend the "life" of a cached file. If the cached file would have expired 120 seconds ago, but maxstale is set to "300", the local cached file will be sent back to the platform without first verifying the status of the file from the source site.

External links:

• Cache - Wikipedia
• Caching on the Plum Voice IVR platform