As most of my readings are focusing on analyzing the operating status of BitTorrent world, in this task, I found more readings are relevant to the issue of free-riding. This paper again take notes on incentives in BitTorrent induce free-riding. Authors believe that the lack of reward and punishment can induce free riding to such a degree that the systems become inefficient.

The interesting thing is, author illustrate the prisoner's dilemma with free riders. When they try to download, they need to face with the conflict between eagerness to download and the unwilling to upload. This implicate not everybody would like to share themselves however they like to get from others. Therefore, an incentive mechanism is developed for free riders.

Of course, it makes me think about if free riding does become widespread, the engineer and scientist will work out the means to prevent it. However, this would probably lead to a negative direction that have unintended consequences, such as a loss of privacy, or user management.

Overall, Free riding is a major issue for filesharing programs, and can greatly degrade their performance. It is a vulnerability that those who wish to make filesharing networks less popular can exploit. BitTorrent has been remarkably resilient to this so far.

This is another article that talk about resist/prevent free-rider behaviors in BitTorrent file sharing network. This paper more analyse from a technical standpoint, propose a quota-based encrypted block trading protocol. According to the simulation result, BitTorrent reflects a better downloading performance, however, it might increase substantially unfairness in uploading blocks among the leechers. Quota-Encryption makes it impossible for free riders to cheat and it also robust against aggressive/conservative strategic peers.
This paper is the second article I have command that relevant to resist free-rider behavior in file sharing network. This will be a valuable reference for me as more and more BitTorrent communities have work out resist free-riders. In the paper Evaluating and improving the fairness policy of the P2P file sharing network eMule/eDonkey (Gruenbacher & Scoglio. 2012), the authors also argue the fairness of contribution from peers. They have similar purpose, methods, and approach.
Whether resisting or rewarding, free-riding is an issue therefore authors intend to develop new technology to against them. However, The transmitted data merely contains information about the time required to download files of different size. In particular, only a hash of the info hash is transmitted, which means that it is not feasible to determine what has actually been downloaded.



Reference:
Li, Y., Gruenbacher, D., & Scoglio, C. (2012). Evaluating and improving the fairness policy of the P2P file sharing network eMule/eDonkey. PEER-TO-PEER NETWORKING AND APPLICATIONS, 5, 40-57. Doi: 10.1007/s12083-011-0106-6

This article examined about the resources supply and demand and the relation between three different BitTorrent communities. It shows that the collaboration within BitTorrent communities is related to the supply and demand, also the content of resources between users, as well as their contribution of the users will affect the download speeds.

This article mentioned that the community resources allocation mechanism which is one of the good aspect for the encouragement of the collaboration within the networks. In either supply or demand users, they only need to contribute more within the system, they can improve the providing bandwidth. Furthermore, as the results from the article, there is the long tail of the peer join rates. It would regard to the torrent popularity that the peer join will drop fast over time. So that the content sharing within BitTorrent communities not just looked at the peer contribution, it should be focus on both, including the content quality and the popularity. All these factors would be affected BitTorrent community's collaboration and contribution.

It is a good resource for me to examine the relationship between peer to peer that work cooperating. If every user has good habits on contributing the content sharing and this kind of allocation mechanism may prevent or deduct 'free rider' as the download speeds would relate to the contribution. Lastly, the peer factor can drives content distribution on the Internet and the mechanisms that better serve humans

To use p2p file sharing networking eMule/eDonkey as example, the content exchange process with credit in eMule/eDonkey and then verify the mathematical model by an agent-based simulation. However, in the example file sharing network, the local credit cannot provide enough fairness as it does not exactly punish free riders. Therefore, a new free-riding control scheme is designed for punishing the free rider and limited their downing activities.

Authors has classified three kinds of requestors, one is who contribute enough content to general peer. General peep will provide all its know source information. A requestor who has lower credit value or without credit, general peer controlling their downloading rate according to their uploading rate. The strangers, as same as free-riders, general peer will only provide very few resources to them. Negative credit will be attached with them while they only ask for resources. There will be no more source information provide once the negative credit reach a pre-defined value.

Authors argue that the performance of the whole P2P file sharing system greatly depends on each peer's cooperation. Free-riders have broken the value of collaboration as they only require for sources and do not upload their own content. This article does not relevant to my selected paper, however, it is a good resource to inspect the relationship between free riders and general peers.

Maciej, W., Mihai, C., Johan, P., & Alexandru, L. (2010). BTWorld: Towards Observing the Global BitTorrent File-Sharing Network. Retrieved from http:// www.pds.ewi.tudelft.nl/~iosup/btworld10lsap_cr.pdf

The relevant information in article is BitTorrent sharing network and their system requirements, therefore to conclude the global view of the BitTorrent network. BitTorrent is a peer to peer file sharing system for exchanging content in the form of files and the process of file sharing contains three levels, the peer level, the swarm level and the community level. As described in the paper, the peers are comprised in the first level and then groups together in a P2P system in the swarm level; in the end, they all come to a BitTorrent deployment, which allow the peers interested in exchanging the same content to start collaborating.

The information in this paper gives great reference about how BitTorrent operate and the requirement of the system. Despite the purpose of this paper is for scientific and system optimization purpose. The advantage of this paper refers to how BitTorrent file sharing network operate - as it generate massive traffic volumes, it is deployed in thousands of independent communities.

The only limitation of this paper to my study that is not gives any concerns about the file sharing network in BitTorrent technology platform.

Knight, M., & Green, L. (2009). BitTorrents and Family Guy: teenage peer group interactions around a peer-to-peer Internet download community. Retrieved from http://www.anzca.net/download-document/41-bittorrents-and-family-guy-teenage-peer-group-interactions-around-a-peer-to-peer-internet-download.html


This paper spoke the development of BitTorrent technologies make downloading comparatively simple to source large multimedia files. Authors pick Family Guy (an animated US television series) as research object as it present as teenage peer group against young adults. The findings of this paper indicate that Family Guy series is collected and consumed as a way of building group cohesiveness and identity.

Nor might the creators have imagined the specific kinds of BitTorrent-enabled, LAN-grounded under-18 school-based communities in urban Australia developing shared cultural practices around their collection and celebration of the series. The result shows internationally, the download culture has been clearly advantageous for Family Guyin marshalling public opinion behind the show and bringing it back from cancellation.

This paper provides very good case study by using the exmple pf downloading Family Guy, therefore to analysis the way that users The issue of download in moral methods is important while talking the BitTorrent technologies.

Bulkowski, A., Nawarecki, E., & Duda, A. (2008). Peer-to-Peer Dissemination of Learning Objects for Creating Collaborative Learning Communities. Retrieved from http://www.editlib.org/p/28630.

In this paper, authors anlyse the limitations of current study community and discuss possible options for a new learning tool base on P2P technologies. The idea of creating collaborative learning communities is to assist learners exchange knowledge, opinion, and experience so that they can learn, understand and help each other.
This paper list new approach based on peer to peer networking and simple to use communication technologies, in order to provide users has a wide and easy distribution of learning objects. In the current P2P systems, authors indicate there is no communication between users exchanging files. Thus, give addition function to the current PSP system may help learners gain more communications.

The advantage of this paper gives a direction for future e learning tool. The main idea is to use P2P enable the creation of collaborative leaning. It also mentions how collaborative community's process in P2P system. This paper is useful for my research because it points out the great value of P2P platform - collaboration. However P2P network for collaborative communities like BitTorrent, authors do not talk in details how these technologies support the community will be the limitation in this paper.

Andrade, N., Mowbray, M., Lima, A., Wagner, G., &Ripeanu, M. (2005). Influences on Cooperation in BitTorrent Communities. Retrieved from http://dl.acm.org/citation.cfm?id=1080198&bnc=1

This article collects the data of BitTorrent data cross multiple file-sharing communities and analyse the factors that affects users' cooperative behaviors. Three terms are important in this analysis article that is freeriding, seeding and sharing ratio. Freeriding refers to the behavior that the user that download without contributing at all, which means not uploading at all. The idea of seeding is a seeder that has finished their downloading but still connected to the torrent upload for the other peers. The definition of sharing ration is the total amount of data the peer has uploaded, divided by the total amount downloaded. The mention of sharing ratio is related to the two ideas above: freerider means zero sharing ratio and a seeder uploading content will thereby increase its sharing ratio.

The later stage of this paper collects data from two BitTorrent communities to measure the correlation between the peer who download in the torrent and the seeding ratio in torrent. Results show as the freeriders and other low-sharing peers are much rarer than freeriders are in other P2P communities. Besides, the seeding ratio is higher in torrents with small file sizes and, at all but one of the sites, is higher in younger torrents. At the two sites where we are able to rank torrents according to their sharing ratios, torrent rank is positively correlated with seeding ratio and with the number of peers in the torrent. In addition, authors believe that social and economic characteristics play a role in determining the amount of cooperation as well.

This paper is useful for my finding as it commentate how BitTorrent community working and the relationship between providers and receivers. However, some of the peers might be seem as freeriders.