Program flow

OpenPSA execution process starts when Apache receives a HTTP request and passes it on to Midgard
The OpenPSA host in Midgard has an active page which calls the OpenPSA Application class

OpenPSA Application calls the ACL Handler, which gets a list of workgroups from the Workgroup Registry
The ACL Handler also loads the configurations of the Components and merges information from this and the Access Control Lists together

OpenPSA Application then calls the URL Handler which parses the URL
If the URL is a file to be served (CSS file, attachment, icon, ...), the URL Handler passes the request to the OpenPSA File Server
In other cases the URL Handler passes the request to a Component
The Component checks its data integrity using an init check method in the Component Interface class
After init check it passes the request together with the given URL path to the Viewer class
The Viewer class then runs the business logic (processes a form, loads data) associated with the particular URL, and calls a Midgard template to display the view