Peer-to-peer i dagens applikationer har visat sig vara av stor användning. Detta beror på att peer-to-peer, både i teorin och i praktiken, har visat sig vara effektivare i att tillhandahålla data, detta utan att belasta en eller flera servrar med uppgiften. Snabba framsteg i mobil networking, tillsammans med användares begär för fler online tjänster och spel i mobila enheter, är anledningen till varför vi har blivit intresserade av att undersöka mobil P2P. De mål vi hade med projektarbetet var att ta reda på de för- och nackdelar som finns med mobil P2P, samt hur P2P kan implementeras och användas i en applikation. Som ett resultat av arbetet utvecklades en mobilapplikation, som använder en centraliserad P2P struktur för att utföra delar av nätverkskommunikationen. De problem som uppstod med routing och NAT löstes med hjälp av applicering av ICE-protokollet. Den utvecklade applikationen och dess P2P element utvärderades sedan i förhållande till den klassiska server-klient modellen. Systemet visade sig där fördelaktigt, när aspekter som responstid och serverbelastning betraktades. Andra aspekter så som anslutningstid, applikationskomplexitet och stabilitet under normala förhållanden var däremot ogynnsamma. Lösningsstrukturen av den produkt som utvecklades är tänkt att kunna användas av andra utvecklare, som riktlinje eller inspiration för andra produkter. / Peer-to-peer in today’s applications has proved to be of great use. That is because peer-to-peer, both in theory and in practice have proved to be more effective in providing data, without burdening one or several servers with the task. Rapid advances in mobile networking, along with users crave for more online services and games in mobile units, is why we have gotten interested in investigating mobile P2P. The goals of the project were to find out the advantages and disadvantages of mobile P2P, and how P2P could be implemented and used in an application. As a result of the work, a mobile application was developed. The mobile application uses a centralized P2P structure to perform parts of its network communication, and solves problems of routing and NAT through use of the ICE protocol. The developed application and its P2P element was evaluated in relation to the classic server-client model. The system proved advantageous when aspects such as response time and server load was considered. Other aspects, such as connecting time, application complexity and stability, were found inferior under normal conditions. The solution structure of the developed product is thought to possibly be of use for other developers, as guidance or inspiration for other products.

Recently, researchers have introduced the notion of super-peers to improve signaling efficiency as well as lookup performance of peer-to-peer (P2P) systems. In a separate development, recent works on applications of mobile ad hoc networks (MANET) have seen several proposals on utilizing mobile fleets such as city buses to deploy a mobile backbone infrastructure for communication and Internet access in a metropolitan environment. This paper further explores the possibility of deploying P2P applications such as content sharing and distributed computing, over this mobile backbone infrastructure. Specifically, we study how city buses may be deployed as a mobile system of super-peers. We discuss the main motivations behind our proposal, and outline in detail the design of a super-peer based structured P2P system using a fleet of city buses. / Singapore-MIT Alliance (SMA)

Recent advances in pervasive computing and peer-to-peer computing have opened up vast opportunities for developing collaborative applications. To benefit from these emerging technologies, there is a need for investigating techniques and tools that will allow development and deployment of these applications on mobile and heterogeneous platforms. To meet these challenging tasks, we need to address the typical characteristics of mobile peer-to-peer systems such as frequent disconnections, frequent network partitions, and peer heterogeneity. This research focuses on developing the necessary models, techniques and algorithms that will enable us to build and deploy collaborative applications in the Internet enabled, mobile peer-to-peer environments. This dissertation proposes a multi-state transaction model and develops a quality aware transaction processing framework to incorporate quality of service with transaction processing. It proposes adaptive ACID properties and develops a quality specification language to associate a quality level with transactions. In addition, this research develops a probabilistic concurrency control mechanism and a group based transaction commit protocol for mobile peer-to-peer systems that greatly reduces blockings in transactions and improves the transaction commit ratio. To the best of our knowledge, this is the first attempt to systematically support disconnection-tolerant and partition-tolerant transaction processing. This dissertation also develops a scalable directory service called PeerDS to support the above framework. It addresses the scalability and dynamism of the directory service from two aspects: peer-to-peer and push-pull hybrid interfaces. It also addresses peer heterogeneity and develops a new technique for load balancing in the peer-to-peer system. This technique comprises an improved routing algorithm for virtualized P2P overlay networks and a generalized Top-K server selection algorithm for load balancing, which could be optimized based on multiple factors such as proximity and cost. The proposed push-pull hybrid interfaces greatly reduce the overhead of directory servers caused by frequent queries from directory clients. In order to further improve the scalability of the push interface, this dissertation also studies and evaluates different filter indexing schemes through which the interests of each update could be calculated very efficiently. This dissertation was developed in conjunction with the middleware called System on Mobile Devices (SyD).