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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