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...f such overlays. Structured overlays, on the other hand, use certain methodology while searching and disseminating information regarding resources. Structured overlay networks such as CAN [26], Chord =-=[27]-=-, Pastry [28], Tapestry [29] and Bamboo [30] create a virtual topology on top of the physical topology. They are formed to overcome the inefficiencies of the unstructured overlay [25]. Structured algo...

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...ys. Structured overlays, on the other hand, use certain methodology while searching and disseminating information regarding resources. Structured overlay networks such as CAN [26], Chord [27], Pastry =-=[28]-=-, Tapestry [29] and Bamboo [30] create a virtual topology on top of the physical topology. They are formed to overcome the inefficiencies of the unstructured overlay [25]. Structured algorithms either...

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.... Ad-hoc interaction can only occur between "strangers" if a sufficient level of trust exists between them. Trust evolves over time as a result of experiences from interactions and local observations =-=[47]-=-. Some of the concepts proposed to dynamically maintain trust levels for P2P file sharing have potential applicability in the ad-hoc real-time collaborative setting [48]. An ad-hoc collaborative P2P-b...

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...actions and local observations [47]. Some of the concepts proposed to dynamically maintain trust levels for P2P file sharing have potential applicability in the ad-hoc real-time collaborative setting =-=[48]-=-. An ad-hoc collaborative P2P-based trust system must be simple, process efficiently, be highly transparent, require minimal human interaction and accommodate both the “on the fly one time” collaborat...

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...overlays, on the other hand, use certain methodology while searching and disseminating information regarding resources. Structured overlay networks such as CAN [26], Chord [27], Pastry [28], Tapestry =-=[29]-=- and Bamboo [30] create a virtual topology on top of the physical topology. They are formed to overcome the inefficiencies of the unstructured overlay [25]. Structured algorithms either guarantee loga...

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...loping systems and models for the field of P2P. Developing systems and models and evaluating existing theories have been identified as pre-requisites for utilizing design science research methodology =-=[51, 52]-=-. Influenced by the design science methodology, this study evaluates existing theories by implementing them in a specific design and attempts to formulate a novel architecture for enabling collaborati...

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...ed, decentralized or hybrid, as illustrated in Figure 1. These topologies or their variants have been in existence for quite some time. A well-known hierarchical system is Domain Naming Service (DNS) =-=[17]-=-, wherein authority flows from the root name servers to the server for the registered name and often down to third-level servers [18]. Centralized P2P is wherein communication is completely centralize...

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...l. All the DHT algorithms, mentioned above, provide certain basic components – node and key identifier space, rules for associating keys to nodes, routing tables and rules for updating routing tables =-=[31]-=-. However, the difference is in the way they employ different routing algorithms [32]. There have been attempts to devise a common Application Programming Interface (API) for different DHT algorithms ...

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...nd key identifier space, rules for associating keys to nodes, routing tables and rules for updating routing tables [31]. However, the difference is in the way they employ different routing algorithms =-=[32]-=-. There have been attempts to devise a common Application Programming Interface (API) for different DHT algorithms [32]. Table 1 illustrates differences in various DHT facilities. Chord, as explained ...

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...o encrypt all messages between collaborators. Further, once such a key is generated, it must be securely shared with other members. Several recent works on how to do that have been recently addressed =-=[37, 38]-=-. 11) Confidentiality through encryption: All messages (voice, video and data) must be encrypted to provide privacy and confidentiality of communication. Using a P2P-PKI approach, this can be achieved...

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...twork to higher-level programmatical view of the peers that make up the network [18]. P2P overlays provide a good substrate for building large scale data sharing and content distribution applications =-=[25]-=-. Similar to general overlay networks, a wide array of research has been published with regards to facilities in P2P overlay. In the context of P2P systems, there are two types of overlays: unstructur...

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..., where two or more people from different locations decide to have an unplanned interaction with one another. Studies have assigned different terms to similar environments – spontaneous collaboration =-=[5]-=- and coalition [6], for instance. The definition used in this study has been influenced by Berket and Agarwal [7]. Ad-hoc collaboration includes all the features that other kinds of group-work support...

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...anging. Existing trust models rely on a centralized database, but P2P systems are decentralized; this makes managing trust an important problem to resolve since users must be their own trust managers =-=[44]-=- Pretty Good Privacy (PGP) lets users increase trust in a transitive manner; and to select a key length appropriate for the situation. Members should be able to express trust in more dimensions, more ...

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...hin the P2P community and offer highly scalable and efficient low-latency search and retrieval of data over an overlay network. Extending these structured overlays, Proximity Neighbor Selection (PNS) =-=[34]-=- algorithm provides options for resolving resources among nodes that are in routing proximity. This is particularly desirable in the case where the usernames are of an email address format user@domain...

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...tion and decentralization have been employed in e-mail, IP routing and Usenet applications [13]. There have been various initiatives that have used P2P infrastructure – voice and video conferencing 2 =-=[14, 15]-=- and content sharing [16]. Operationally, P2P needs to provide improved capabilities to a user, wherein a 2 Skype, a commercial initiative, is a noteworthy contribution towards voice and video confere...

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...o encrypt all messages between collaborators. Further, once such a key is generated, it must be securely shared with other members. Several recent works on how to do that have been recently addressed =-=[37, 38]-=-. 11) Confidentiality through encryption: All messages (voice, video and data) must be encrypted to provide privacy and confidentiality of communication. Using a P2P-PKI approach, this can be achieved...

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...e. A well-known hierarchical system is Domain Naming Service (DNS) [17], wherein authority flows from the root name servers to the server for the registered name and often down to third-level servers =-=[18]-=-. Centralized P2P is wherein communication is completely centralized with many clients connecting directly to a single server. Traditional database systems, web server systems and SETI@Home [19] are s...

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...loping systems and models for the field of P2P. Developing systems and models and evaluating existing theories have been identified as pre-requisites for utilizing design science research methodology =-=[51, 52]-=-. Influenced by the design science methodology, this study evaluates existing theories by implementing them in a specific design and attempts to formulate a novel architecture for enabling collaborati...

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... Gnutella [21], Freenet [20]), collaboration (e.g., Groove [14]) and platforms (e.g., JXTA [22]). Figure 1: Peer-to-Peer Topologies Overlay networks have been recommended for self-organizing networks =-=[23]-=-, a critical feature of P2P infrastructure. Overlay networks have been identified to be effective design mechanisms for deploying heterogeneous, large-scale, P2P systems [24]. The purpose of P2P-based...

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...er of IETF drafts that identify various topical issues in implementing such applications. Furthermore, there are various proposals that have been published in some of the major conference proceedings =-=[3, 33]-=-. Our objective is to design and develop an ad-hoc collaboration tool that utilizes the capabilities of underlying DHTs to map users to location and takes full advantage of standards such as SIP for e...

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...e integrity, ability, or character of a person or thing to behave properly. Humans use trust every day to promote interaction and accept risk in situations where only partial information is available =-=[42]-=-. Without risk, there is no reason to trust. With operational trust, a peer must make a rational decision based on knowledge of possible outcomes for trusting and not trusting. One goal of a trust sys...

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...eo and conferencing applications that help us collaborate with participants on the Internet. Following this continuum, several recent standards such as Session Initiation Protocol (SIP) [1] and H.323 =-=[2]-=- have enabled voice and video conferencing over Internet Protocol (IP). However, experience has revealed that these systems are expensive, require centralized services, and often require intensive adm...

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...entities with no administrative interference. A number of solutions are being tested in standards organizations – Simple Traversal of User Datagram Protocol Through Network Address Translators (STUN) =-=[35]-=-, Traversal using Relay Network 297sAddress Translators (TURN) 3 and Interactive Connectivity Establishment (ICE) 4 . These solutions are under consideration and are being widely tested. The main draw...

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...e examples of such overlays. Structured overlays, on the other hand, use certain methodology while searching and disseminating information regarding resources. Structured overlay networks such as CAN =-=[26]-=-, Chord [27], Pastry [28], Tapestry [29] and Bamboo [30] create a virtual topology on top of the physical topology. They are formed to overcome the inefficiencies of the unstructured overlay [25]. Str...

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... self-organizing networks [23], a critical feature of P2P infrastructure. Overlay networks have been identified to be effective design mechanisms for deploying heterogeneous, large-scale, P2P systems =-=[24]-=-. The purpose of P2P-based overlay networks is that they abstract the complicated connectivity of a P2P network to higher-level programmatical view of the peers that make up the network [18]. P2P over...

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...e single dimension of trust with PGP [45]. In trust and reputation based models, each peer attaches a trust score to every other peer to avoid interacting with those having insufficient trust levels. =-=[46]-=-. True collaboration teams usually start with known people, with 301sunknown members added as needed. Ad-hoc interaction can only occur between "strangers" if a sufficient level of trust exists betwee...

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... establish point-to-point and multi-point voice and video sessions. SIP provides for such capabilities. SIP is also designed to provide Instant Messaging (IM), Presence and file-transfer capabilities =-=[36]-=-. It is also designed to advanced session services such as caller ID and voice messaging. D. Security requirements 9) Authentication: When a user calls using this new P2P-SIP system, one should be abl...

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...Internet Protocol (IP). However, experience has revealed that these systems are expensive, require centralized services, and often require intensive administrative support to configure and maintain 1 =-=[3]-=-. Peer-to-Peer (P2P) technology [4], on the other hand, has the potential to replace expensive centralized entities and offer true distributed systems that can facilitate minimal infrastructure for co...

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...perience has revealed that these systems are expensive, require centralized services, and often require intensive administrative support to configure and maintain 1 [3]. Peer-to-Peer (P2P) technology =-=[4]-=-, on the other hand, has the potential to replace expensive centralized entities and offer true distributed systems that can facilitate minimal infrastructure for communication capability. P2P systems...

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...e people from different locations decide to have an unplanned interaction with one another. Studies have assigned different terms to similar environments – spontaneous collaboration [5] and coalition =-=[6]-=-, for instance. The definition used in this study has been influenced by Berket and Agarwal [7]. Ad-hoc collaboration includes all the features that other kinds of group-work support. The distinguishi...

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...dies have assigned different terms to similar environments – spontaneous collaboration [5] and coalition [6], for instance. The definition used in this study has been influenced by Berket and Agarwal =-=[7]-=-. Ad-hoc collaboration includes all the features that other kinds of group-work support. The distinguishing factor, however, is the support of ad-hoc scenarios. Frequently on-line collaboration includ...

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...] or Microsoft Live Meeting [9]. Another kind of teamwork involves collaboration on files, typically with unstructured content and often on a discontinuous basis, e.g., Lotus’ Domino Document Manager =-=[10]-=-. This category involves heavy use of filesharing and e-mail. Multimedia (IP telephony and video-conferencing) for which expensive servers are often required is yet another type of collaboration. Due ...

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...e work planned for the study. 2. Background 2.1 P2P P2P is a class of applications that take advantage of resources – storage, cycles, content, human presence – available at the edges of the Internet =-=[11]-=-. The central idea in P2P systems is that every node in a network is a server and a client. Every node is able to exchange resources and collaborate with no dependence on a central entity. P2P systems...

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... ownership, anonymity and privacy [4]. P2P is being viewed as an infrastructure that could effectively serve as an operating system for the Internet, which is global-scale and heterogeneous in nature =-=[12]-=-. In delivering this vision, P2P is considered as an important development in distributed computing where the network is really the computer. In this kind of infrastructure, scalable IP routing can be...

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...on is important so that different kinds of media can be exchanged. Principles of P2P with a mix of centralization and decentralization have been employed in e-mail, IP routing and Usenet applications =-=[13]-=-. There have been various initiatives that have used P2P infrastructure – voice and video conferencing 2 [14, 15] and content sharing [16]. Operationally, P2P needs to provide improved capabilities to...

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...e been employed in e-mail, IP routing and Usenet applications [13]. There have been various initiatives that have used P2P infrastructure – voice and video conferencing 2 [14, 15] and content sharing =-=[16]-=-. Operationally, P2P needs to provide improved capabilities to a user, wherein a 2 Skype, a commercial initiative, is a noteworthy contribution towards voice and video conferencing 292suser’s machine ...

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...ples of centralized P2P topologies. In decentralized topology, there is no central point of control. Peers communicate symmetrically and have equal roles. Examples of a pure P2P model include Freenet =-=[20]-=- and Gnutella [21], wherein resources are distributed among participating nodes. In a hybrid model, a central entity is contacted to obtain meta-information, such as the identity of the peer on which ...

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... taxonomy of P2P systems classify them into distributed computing (e.g., SETI@home [19]), file sharing (e.g., Gnutella [21], Freenet [20]), collaboration (e.g., Groove [14]) and platforms (e.g., JXTA =-=[22]-=-). Figure 1: Peer-to-Peer Topologies Overlay networks have been recommended for self-organizing networks [23], a critical feature of P2P infrastructure. Overlay networks have been identified to be eff...

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...nal decision based on knowledge of possible outcomes for trusting and not trusting. One goal of a trust system is to enable one peer to determine the likelihood that another peer will behave properly =-=[43]-=-. Ad-hoc groups are self-provisioning; members can invite other collaborators to join their group, and assign them various privileges; they may be affiliated with many different organizations. A group...

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... in a transitive manner; and to select a key length appropriate for the situation. Members should be able to express trust in more dimensions, more richly, than the single dimension of trust with PGP =-=[45]-=-. In trust and reputation based models, each peer attaches a trust score to every other peer to avoid interacting with those having insufficient trust levels. [46]. True collaboration teams usually st...