Cache Policy Manager - Policies

A cache policy represent a single class of cachable objects:

• class membership is defined by predicate, a TALES expression with access to the following top-level names:

  object

  the object itself

  view

  the name of the view method

  keywords

  keywords passed to the request

  request

  the REQUEST object itself

  member

  the authenticated member, or None if anonymous

  modules

  usual TALES access-with-import

  nothing

  None

  time

  A DateTime object for the current date and time

• The "Last-modified" HTTP response header will be set using mtime_func, which is another TALES expression evaluated against the same namespace. If not specified explicitly, uses object/modified.
• The "Expires" HTTP response header and the "max-age" token of the "Cache-control" header will be set using max_age_secs, if passed; it should be an integer value in seconds.
• The "Vary" HTTP response headers will be set if a value is provided. The Vary header is described in RFC 2616. In essence, it instructs caches that respect this header (such as Squid after version 2.4) to distinguish between requests not just by the request URL, but also by values found in the headers showing in the Vary tag. "Vary: Cookie" would force Squid to also take Cookie headers into account when deciding what cached object to choose and serve in response to a request.
• The "ETag" HTTP response header will be set if a value is provided. The value is a TALES expression and the result after evaluation will be used as the ETag header value.
• Other tokens will be added to the "Cache-control" HTTP response header as follows:

  no_cache=1 argument => "no-cache" token

  no_store=1 argument => "no-store" token

  must_revalidate=1 argument => "must-revalidate" token