Using Trackback to Support Citation Notification Services ========================================================= Brian Matthews, Katie Portwin and the Claddier Team --------------------------------------------------- The notion of Linkbacks between websites has been developed to enable authors to keep track who is linking to their pages. One of the most well known of several protocols which has been developed for Linkbacks is Trackback which has been developed within the Blogging system, MoveableType. A similar problem to tracking links between blog articles is found in repositories of research outputs, such as archives of acedemic publications or research data. Publications use citations to refer to one another, but repositories are typically not informed when there are publications referring to their content. This is useful information in judging the value of a paper. This presentation considers the use of Trackback to support automatic notification to propagate citation information between repositories to provide a simple light-weight peer-to-peer service which is as widely applicable as possible and can be implemented quickly. The original Trackback protocol has been adapted to the requirements of citation notification via a richer set of metadata fields which can be sent with the data using RDF, and a richer interaction between the peers. Futher extensions include a "reverse Trackback" propagating information to the initiator of the notification via RDF embedded in the page, making the protocol two-way. Also a notion of "anti-trackback" has also been identified to enable the withdrawal of notifications. Further, we consider approaches to a well-known shortcoming of the Trackback protocol, that of bogus trackbacks as a mechanism for distributing spam messages. We describe the modifications of the protocol, and the extended protocol's implementation and usage within repositories.