Clickthrough

part of the ArsDigita Community System by Philip Greenspun
Here's the data model (from /packages/acs-core/community-core.sql): 

create table clickthrough_log (
        local_url       varchar(400) not null,
        foreign_url     varchar(300) not null,  -- full URL on the foreign server
        entry_date      date,   -- we count referrals per day
        click_count     integer default 0
);
Note that we key this table by the URL on our server rather than by a page ID. Note further that this local URL does not include the beginning / (a legacy from the old days but I guess it is OK). This enables page authors to build pages without being aware of the internal page_id by which our system might know the comments or links associated with a page. Here's what a link out reference looks like: 

B&H Photo
This is a reference on the page http://photo.net/photo/where-to-buy, sending readers over to http://www.bhphotovideo.com/.

For legacy sites that used to log clickthroughs with my old system, there is a parameter in the ad.ini file that lets you specify a custom regular expression to permit old-style references that include a realm, e.g.,


/philg/photo/where-to-buy?send_to=http://www.bhphotovideo.com/">B&H Photo
Here's the necessary magic from my ad.ini file: 

[ns/server/photonet/acs/click]
CustomREGEXP=/ct/philg/(.+)$