In my previous article on the theme of notification for reference and reuse I introduced the concept of trackback, a protocol for notifying the author(s) or readers of an article that the original work or derivation is being reused/ referenced. Trackback also enables aggregation of reuse/reference summaries plus links to all such reuses/references. In this article I explore the topic in a little more depth. First let's remind ourselves what trackback is. The specification for the trackback open protocol was developed by Movable Type for implementation in all weblog tools. Movable Type describe trackback as an:
“… architecture for peer-to-peer communication and notifications between web sites. The protocol is based on the priciple of push, rather than pull--if you want to share information with another website, you initiate the connection, rather than waiting for the other website to discover you (and your information).”
Keep in mind that, in the weblog world, trackback is not a mechanism for policing or inhibiting reuse. The contrary is desired. Weblog authors usually want to see lots of reference and reuse as long as appropriate credit is given. Appropriate reference or reuse of an article is better than concepts, ideas, arguments, perspectives being 'locked in' to one source or bound to one context. One of the difficulties, however, is weblog articles may well be being referenced/reused elsewhere, but the original author may never get to know about it unless the new author chooses to inform them. Here then is the driver for candidate solutions like trackback.
One of the potential limitations of trackback is that an article's author has to be sufficiently motivated/caring/sharing to be prepared to inform another author that they are referencing their work. For some the additional step may prove too great an impediment. But there have been some developments in this area in the form of trackback autodiscovery.
As the creator of trackback the Movable Type engine has arguably the most sophisticated implementation of the protocol. For instance, its trackback auto-discovery will inform other sites (if they are trackback enabled) an article's author is referencing them without the author having to do anything.
“Movable Type will look for any links in your weblog post, and use auto-discovery to determine if those links are TrackBack-enabled. If they are, Movable Type will automatically send TrackBack pings to those sites. You don't need to use the URLs to Ping field, nor do you need to use the bookmarklet to select TrackBack-enabled posts.”
pMachine Pro, the weblog engine currently used by Auricle, also has trackback autodiscovery features but only its bookmarklet feature (an alternative to the main article authoring interface).
Some implementations of trackback, e.g. pMachine, appear to make the assumption that an article is only ever going to reference or reuse just one other article and so only make provision for the entry of a single trackback url at the article authoring stage. For example, in this article, because I've only the facility for the entry of one trackback url, even if I had quoted extensively from several of the sites I mention in the 'useful links and further reading' section my system would only be able to automatically inform a single member of that list that I've referred to their material.
What if a site lacks any trackback features? In that case a number of developers have created a manual trackback form which can be used to post reference or reuse data to a trackback site. For example, here is a manual trackback web form by Paul Burdick (of pMachine fame) which you can use to make an entry which will then be inserted into the relevant Auricle article. You'll need to know what an Auricle article's trackback url is; this is also displayed when you select the article's trackback link.
Useful links and further reading
Learning Object Reuse Acknowledgment (LORA)
Alan Levine describes part of the rationale for leveraging trackback in the Maricopa Learning eXchange.
PingBuddy vs. Simpletracks - and the History of the Trackback Form
This is one for those who want to implement trackback in non-trackback web applications.
Trackback development
From Movable Type the originators of the trackback protocol. Here you will find the trackback specification, latest developments, and also a Beginners Guide to Trackback. Just ignore the Movable Type specific references if you're using an alternative system.
Take your trackbacks and dangle
Auricle attempts to offer a variety of viewpoints. John Gruber gives us a fairly indepth critique of Trackback
Too-Daring Fireball
Just to show Auricle is balanced. Phillip Winn, who's site has been around since 1995, offers us a critique of John Gruber's critique.
Trackbacks in Winamp and Trackbacks in iTunes
I include these to illustrate the imaginative use of trackbacks; in this case an mp3/media player sends trackbacks to a weblog.
