An Open Architecture for Supporting Collaboration on the Web D. DeRoure, W. Hall, S. Reich Multimedia Research Group University of Southampton, UK dder, wh, sr @ecs.soton.ac.uk A. Pikrakis Department of Informatics University of Athens, GR pikrakis@di.uoa.gr G. Hill Multicosm Ltd, UK gjh@multicosm.com M. Stairmand Parallel Application Centre Southampton, UK mas@pac.soton.ac.uk Abstract The MEMOIR framework supports researchers working with a vast quantity of distributed information, by assisting them in finding both relevant documents and researchers with related interests. It is an open architecture based on the existing Web infrastructure. Key to the architecture are the use of proxies and the use of an open and extensible message protocol for communication: to support message routing for dynamic reconfiguration and extension of the system, to collect information about the trail of documents that a user visits, and to insert links on-the-fly. In this paper we present the MEMOIR architecture and its rationale, and discuss early experiences with the system. 1. Introduction Effective access to documents and effective collabora- tion between researchers can be crucial to the competitive- ness of large companies. MEMOIR, which stands for Man- aging Enterprise-scale Multimedia using an Open Frame- work for Information Re-use, addresses this problem by providing the user with extra assistance in these tasks in return for minimal extra effort by the user. Unlike other rec- ommender systems, MEMOIR recommends people as well as documents. The application areas that we focus on per- tain to large distributed organisations that have to manage diverse sources of information and that rely heavily on their research and development function. The system described in this paper is currently being trialled by users in two such organisations. The MEMOIR architecture is an evolution of the Dis- tributed Link Service (DLS, [4]). While the DLS, like other open hypermedia systems, treats hypermedia links as first class objects, MEMOIR additionally promotes another kind of object: the trail. A user’s trail is the set of actions on documents that they have visited (such as opening the doc- ument) in pursuing a certain task. By matching trails, we match users. MEMOIR lets the user ask questions such as ‘who else has read this document?’ and ‘what else should I read?’. MEMOIR can be thought of as a navigation assistant, and it borrows from DLS the idea of implementing this agent as an HTTP proxy. With the proxy on a separate ma- chine, this approach has minimal impact on the user’s desk- top (perhaps requiring a routine configuration change) and it steals no cycles. Trails, like links, are persistent, shared objects, hence multiple proxies communicate with a logi- cally central (but perhaps physically distributed) database to store and process them. The notion of supporting collaborative work by hyper- text technology dates back to the very first ideas of hyper- text, as expressed by Bush’s ‘Memex’ [3]. He envisaged trails (also called paths [7] [22] or footsteps [15]) in order to provide a mechanism for finding a user’s personal infor- mation but also in order to allow these trails to be available to other users. Reading (i.e. opening and viewing) a docu- ment might be the most common type of activity in a trail, though there are many other actions users perform; for ex- ample, bookmarking, printing or mailing a document could indicate a special interest. In the system described in this paper, we focus on ‘open document’ actions and support collaboration by providing agents that perform intelligent analysis on the documents being viewed by users. The architecture is presented in section 2. Section 3 de- scribes experience we have had with the framework, both as a research vehicle and at the end user sites. We report on related work in Section 4, followed by concluding remarks.