Anatomy of a request
This is a description of how EPrints and Apache handle an incoming request. Understanding this flow helps understand how an Access Control layer can be added to the system.
I will assume that you know how to locate a perl module file from the module name (e.g.
EPrints::Apache::Rewrite will probably be
~/perl_lib/EPrints/Apache/Rewrite.pm, although this is not always the case!).
Below are relevant parts of config files and perl modules that are used with when processing a request:
- Apache core config
PerlSwitches -I/home/eprints/eprints-3.3.12/perl_lib PerlModule EPrints PerlPostConfigHandler +EPrints::post_config_handler
The post_config_handler does some sanity checks on the EPrints setup (e.g. is Apache listening to the ports that the repositories are configured to work under) See: http://perl.apache.org/docs/2.0/user/handlers/server.html#C_PerlPostConfigHandler_ for more info about the post_config_handler
- Apache repository config
<VirtualHost *:80> ... PerlTransHandler +EPrints::Apache::Rewrite </VirtualHost>
This leads us to the backbone of EPrints - the Rewrite module - where URL_REWRITE_* triggers are called; content negotiation can happen, as well as many other wonderous things!
- Explain flow of Rewrite
- content negotiation
- permit on DataObj
- can_request_view / can_user_view
- summary pages (content neg/ URL rewrite)
- DOI - 5 metadata elements
- 40x handling
|Access Control Layer|