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On P2P Collaboration Infrastructures. Manfred Hauswirth, Ivana Podnar, Stefan Decker Infrastructure for Collaborative Enterprise, 2005. 14th IEEE International Workshops on 13-15 June 2005 Speaker : Ching-Chen Chang Date:2007/12/13  . Overview.

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on p2p collaboration infrastructures

On P2P Collaboration Infrastructures

Manfred Hauswirth, Ivana Podnar, Stefan Decker

Infrastructure for Collaborative Enterprise, 2005. 14th IEEE International Workshops on

13-15 June 2005Speaker : Ching-Chen Chang


  • The paper is about that how distributed mobile collaboration with P2P approaches could be applied.
related work 1 2
Related Work(1/2)
  • Three different collaboration scenarios
    • Ad-hoc
      • offer temporary support possibly in a limited geographical area, and enable group members to flexibly interact and communicate with limited collaboration functionalities.
    • Short-term
      • limited time spans, and enable virtual organizations and teams to collaborate in order to satisfy a mutual objective
    • Long-term
      • set up by collaborating organizations and teams for longer time periods.
      • Usually a centralized infrastructure is used for this type.
related work 2 2
Related Work(2/2)
  • Three technological strategies
    • A standard centralized solution
      • It seems mainly adequate for long-term collaborations.
    • A pure P2P approach
      • This approach would be suitable for ad-hoc and short-term collaborations, but presently can be considered for supporting ad-hoc scenarios which do not require high-reliability and availability of resources.
    • A mixed model
      • Provides support for short-term and long-term collaborations.
  • Centralized systems require the setup and maintenance of the server.
  • It requires the infrastructure to be in place and configured a-priori.
  • It is costly in terms of hardware, software and time.
  • The P2P approaches could be applied to remedy these shortcomings.
introduction 1 2
  • Key characteristics of distributed mobile collaboration are the requirements for flexible interaction styles among users, and ubiquitous mobile access to resources and collaborators.
introduction 2 2
  • Much of an overhead, and a more flexible support for short-term and ad-hoc collaboration is required that takes into account user mobility.
  • The issue of possibly limited functionality of mobile devices
  • Users can find and access both required resources and available services.
  • Efficient distributed search based on semantic descriptions of the involved data, users, services.
  • Distributed storage, and secure and authenticated

access to resources is needed.

  • Group communication models.
  • A team membership management service which should be augmented by a trust model.
architecture 1 2
  • Architecture for P2P collaboration systems.

Device-dependent Presentation

Higher-level services(e.g. instant messaging, white board, alerts)

Authenticated and Secure Access Mng.

Distributed Storage

Distributed Trust Mng.

Membership Mng.





architecture 2 2
  • The transport layer provides the basic network communication between peers.
  • The peer-to-peer overlay on top of this layer supports basic of nodes, indexing of data and efficient distributed search to increase resource availability.
  • The five basic lower-level collaboration services which offer supporting services for building end services for mobile collaborators.
distributed search and storage 1 4
Distributed Search and Storage(1/4)
  • Distributed search and replication mechanism
    • Discovering replicas and supporting up-to-date.
    • The consistency guarantees provided by the replication mechanism determine the freshness of the information.
  • Distributed indexing system offers the replication and load-balancing for the index information.
  • Resources may not be able to be accessed if the corresponding peer is offline.
  • Replication is required to ensure available of the data.
distributed search and storage 2 4
Distributed Search and Storage(2/4)
  • Distributed archival storage projects split resources into digestible pieces and distribute them.
  • Coding strategies are needed, but the data manipulation operations are expensive.
  • Updates in P2P system mean index updates.
  • The key question for the distributed storage is which data should be replicated.
distributed search and storage 1 41
Distributed Search and Storage(1/4)
  • It is the question whether complete consistency is required or some relaxed model would be tolerable.
distributed search and storage 4 4
Distributed Search and Storage(4/4)
  • Relaxed consistency
    • When a peer downloads data, it becomes a replica.
    • In case of an update, all replicas would be informed.
    • Queries always include the version of the found data.
    • Conflicting updates require manual system.
    • If data is unavailable, the requester can subscribe to the system to be notified when the data becomes available.
publish subscribe 1 2
  • A P/S system provides an efficient service which pushes the data at the time of its publication to interested subscribers.
  • The major challenge for P/S in such environments is related to the design of efficient routing strategies that can deal with network changes (“churn”) while preserving high-expressiveness of subscriptions and low latency for delivered data.
publish subscribe 2 2
  • How to match a published notification to the existing subscriptions in the index and how to build delivery trees based on P2P systems. These and related questions are subject of ongoing research.
  • Presence service maintains and offers information on users’ presence and contact information.
  • A user can define a default communication point which is activated in case the current presence information is unavailable.
  • P/S is the natural interaction style for the presence service.
  • Presence implementation can largely rely on an existing P/S implementation taking into account an extension related to user privacy.
  • We are convinced that P2P-based collaboration is a paradigm that meets the requirements of users, but there is still a lack of enabling technologies which have to be researched and implemented.
  • On P2P Collaboration Infrastructures


  • P2P架構發展與議題