repoze.squeeze

This package provides a WSGI middleware component which "squeezes" HTML documents by merging browser resources (javascript and stylesheets).

It uses statistical analysis to determine the optimal bundles based on the HTML documents that pass through it. Vary-headers are observed, as are resource expiration dates.

Documents that are not squeezed are given the 'no-cache' pragma in an expectation that we will be able to squeeze it after sufficient burn-in. Squeezed documents are served with expiration dates no later than the expiration dates of the squeezed resources which it references.

Usage

Configure the middleware with the following two options (required):

@cache_dir: Relative path to a directory where we store squeezed resources

@url_prefix: Path segment or full base URL that will be used to serve the cache directory as static files.

The following option is optional:

@threshold: Floating-point parameter that controls the merge to apperances threshold. This parameter can normally be left at the default (0.5).

In addition, you must configure the WSGI application to serve the file cache directory from the url_prefix (e.g. "cache").

Invalidation

To invalidate the file cache, upstream applications can set the "X-Squeeze-Invalidate" header to a true value; note that before the application is called, the middleware adds this key to the environment such that applications which can't modify the environment can still flag for invalidation:

invalidate = environ["X-Squeeze-Invalidate"] invalidate()

This will reset the file cache registry; note that no cache files are ever deleted (to preserve web server integrity). You can manually purge the file cache at any time be deleting the files (this is allowed at run-time).