SiteAccess started as a Product to enable Zope Virtual Hosting, then became more generalized. Virtual Hosting is the ability to publish sub-objects of a Zope hierarchy as though they were the root of their own site. For example, it allows 'http:/www.silly-walks.org/current' to publish the Zope object 'silly-walks/current' instead of just 'current'.
As of version 0.1.1, SiteAccess provides the ability to force ZPublisher to call objects of your choice as it enters any folder. With this capability, you can designate a method in the Zope root to examine the request parameters and alter or replace the URL.
SiteAccess dynamically patches ZPublisher to check for a __before_traverse__ property on each object it traverses, and call the method(s) listing in the property if it exists. This allows drop-in objects (such as SiteRoot) to control traversal without colliding with any __bobo_traverse__ method which may already exist.
If an Access Rule is broken, and is preventing normal access, it can be fixed by visting URL 'http://www.whatever.com/__no_before_traverse__/path/to/rule/manage_main'