Freelib: A Self-sustainable Digital Library for Education Community Ashraf Amrou, Kurt Maly, Mohammad Zubair Computer Science Dept., Old Dominion University

Outline Introduction/Motivation P2P Based Digital Library Network Architecture Current Status Conclusion

Motivation Efficient Infrastructure for Dissemination – Digital libraries are the cornerstones of modern learning environment. They provide an infrastructure for publishing and managing quality content so it is discovered easily and effectively. Cost Effective – Digital libraries provide cost-effective access to a wealth of information for remote and geographically dispersed users, thus making them an effective tool for online learning environment

Problems Centralized Framework – Requires an organization in a domain/community to take a lead in not only providing the hardware and software infrastructure to support a digital library, but processes to develop and maintain the content Evolving Communities – With time a community ’ s interest seems to grow out and move to a different topic, however the processes and interfaces that have been put in place are not flexible to accommodate the changing interest of the community. Distributed Membership – Problem of building a community where members are distributed, do not know of other members, do not know of available interest areas, yet still want to come together in a community of common interest.

Approach Digital Library architecture (Freelib) based on P2P model that is scalable and supports communities and domains evolving from the bottom up. A P2P network is a distributed network with no central control and consists of nodes running identical software. Example P2P networks for file sharing: Gnutella, Napster, and Kazaa

Issues Keeping the network connected in the presence of frequent joining, re-joining, and leaving of participants Maintaining a low barrier for building communities with diverse interests Providing support for new and evolving communities with changing interests. The key in our vision of supporting evolving communities is to build a network with nodes clustered by access patterns. The major challenges in building such a library are:

Network Architecture The network architecture of Freelib consists of two overlaying networks: access network and support network. The access network topology is characterized by the user access pattern The support network topology is determined by an adaptation of the Symphony protocol. The Symphony protocol preserves the connectivity and small world properties of the network for supporting efficient search.

Network Architecture Figure 1: Network architecture, showing the access and the support network

Key Features: Evolving Communities Friends: every node keeps a list of preferred peers The friend list is ranked based on access patterns with higher ranks given to peers having higher access Nodes migrate on the ring so that nodes that share common interest occupy adjacent locations Note: by ‘ Access ’ we mean access of full-text document. The reason ‘ Search ’ is not considered is simple: user may get lots of search results that she may consider not interesting. On the other hand, download of full-text after seeing the metadata about the item is a better indication that the document is of interest to user

Key Features: Friend Ranking Ranking of friends N: is the total number of outgoing accesses to all nodes during a time interval t. n i : is the total number of outgoing accesses to i th friend in the list. P: is the total number of incoming accesses from all nodes during a time interval t. p i : is the total number of incoming accesses from i th friend in the list.  : is the weighting factor in the range 0 to 1 where =1 ignores incoming accesses in the ranking calculation; and  = 0 ignores outgoing accesses in the ranking calculation.

Key Features: Migration Migration enables evolution of communities When: if my top ranked friends are far away on the ring, it is time for me to join them In the steady state, most of the short contacts are identical to access friends

Key Features: more search options Search query: – Simple keyword search – Advanced search – Metadata based: author = ‘ John Smith ’ Search type: – Friend search: search only friend nodes (this one is suitable for nodes with community evolution done and is expected to return the most interesting results) – Local search: search friends and neighbor nodes (after migration, a node should use this mode to discover potential friends after migration is done) – Global search: search friends, neighbors, and distant links also (this is suitable for newcomers until they join their communities)

Freelib Client Architecture Search/Access Publish History/Log Collection MD + Full-text + Indexes Messenger Network Agent Friends & Contacts P2P network Main UI Log Manager Registry HTTP Collection Manager Figure 2: FreeLib client Architecture

Current Status - Implementation Phased Implementation: start with basic features, then each phase adds more features and enhances existing ones Phase 0: establish a small network and show the Search and Access protocols in motion Later phases: complete Network Protocol implementation, provide advanced search tools, etc.

Current Status - Phase 0 Implement publish, search, access, access log and other supporting modules such as Http, messenger, collection manager, registry, etc. Testbed Build a small p2p network (5 nodes: n1, n2, n3, n4, n5) Publish some documents Perform some searches (simple keyword search for now) Do some accesses (downloads of full-text) Show how the friend list is changing based on the accesses.

Figure 3: Node 1 and Node 2 of Phase 0 demo (node 1 on the left) n3 n5 n2 n3 n4 n1

Figure 4:Node 3 and Node 4 of Phase 0 demo (node 3 on the left) n5 n1 n2 n5 n2

Future work Complete implementation of network protocol and enhanced implementation of other modules Address scalability issues regarding collection size and number of requests. Need to have indexing in the collection manager Testbed and/or simulation to evaluate the protocol Support for OAI protocol to allow interaction with OAI service-/data- providers in the future

Conclusion High school teachers nation-wide can build their own community to publish and exchange school project ideas, class syllabuses, classroom materials. Faculty members of universities nation-wide can use such a system to publish and make available their own publications, project reports, course material and to search for publications of interest to them. Students can create collections of material related to their courses and also to their private life. Freelib will have potentially a broad impact on the education community, as there are many target communities that can benefit from such a system.