On some of the scrolling bookmarks you'll notice that there is a ★ character - this means the bookmark is a solidly popular bookmark that is continuing to get attention.

The star is calculated based on velocity of bookmark activity, if a URL is getting bookmarked every day, it should have a star next to it.

[[LiveMarks]] consists of two parts: an import script and a display script. "import":http://sandbox.sourcelabs.com/livemarks/livemarksImport.txt , "display":http://sandbox.sourcelabs.com/livemarks/livemarks.txt

h1. The import script

The import script is run via a cron job. It runs all the time every day, pulling in the [[del.icio.us]] [[RSS]] feed. In case del.icio.us feeds are inaccessable, or overflow happens, LiveMarks uses a system of redundant mirrors to maintain a steady stream of bookmarks.

h2. Uniqueness

"RSS Item Uniqueness":/RSS/RSS+Item+Uniqueness is a hard problem. Like most [[aggregator]]s, LiveMarks uses an imperfect solution that works most of the time: it takes arbitrary uniqueness criteria and anything that doesn't fit within this criteria is ignored.

LiveMark's uniqueness criteria works as follows: each bookmark has a set of properties that includes an author, a link, and a title. These are hashed and put into a unique hash column in the database.

h1. The display script

The display script uses [[AJAX]] to populate the client bookmark cache without refreshing the page and [[script.aculo.us]] and some custom [[Javascript]] to get the effect of links scrolling down the page.

After a while, in order to prevent link overload, the script wipes out the bottom of the list of links.

Popularity is calculated by sorting link bookmark frequency within a relatively recent time period and cutting off after a set limit. Bookmark newness is calculated by comparing a url against the database of known links and finding if the bookmark appears before a very recent time period.

h1. Open Source Projects used

* [[Linux]] [[Apache]] [[MySQL]] [[PHP]] -- my current [[web-framework]] of choice.

* [[MagpieRSS]] -- the one and only [[RSS]] library for [[PHP]]

* [[XHConn]] -- very simple [[Ajax]] library

* [[script.aculo.us]] -- Neato [[Javascript]] visual effects library

* Written using [[Vim]] over [[SSH]]