Tesis doctoral de Rodrigo Godoi
A video on demand (vod) system provides multimedia content to a set of clients in independent manner; users connect to the system, choose the content to view and start enjoying the service at any given moment. The video is down-streamed to the client, who receives, decodes and displays the content always expecting guaranteed quality of service (qos) from the system. One of the main goals in designing vod services is to support a great number of concurrent requests generated by geographically distributed clients; vod systems must achieve a feasible large-scale and high-quality service with the lower costs and fewer deployment restrictions. recently, multimedia streaming distribution in the internet presented a spectacular growing. The internet is the most popular environment of connected users and is deployed throughout the world. Owing to the public and global scale features of internet, it has become the most important environment to deploy large-scale video on demand service (lvod). owing to the limitations of centralised server-client model, peer-to-peer (p2p) and multicast approaches are widely applied in the multimedia distribution to improve system scalability and performance by sharing resources. P2p is based in the free cooperation of equals in view of the performance of a common task; it takes advantage of available resources at the end host side (storage, content, bandwidth, power processing etc.). The multicast is a communication strategy where a sender has the capability to transmit information that can be received concurrently by a group of interested destinations. Nevertheless, p2p and multicast paradigms add new issues in the design of internet vod services. Peers are heterogeneous in their resources and act by their own free will, coming and leaving the system at any time; the lack or the change of data source provoked by peer faults strongly affects the qos in vod systems based in p2p and multicast techniques. fault tolerance has become a major issue in p2p-based vod services in order to guarantee qos. The fault tolerance mechanism is achieved through the exchange of control messages; moreover, the failure treatment is time limited for providing error absence and consequently maintaining the qos. A good control scheme is needed and its design must be careful owing to the soft real-time restriction of multimedia service and the overhead imposed on the system. this thesis presents a fault tolerance scheme (fts) that works by constructing a backup system in a distributed manner, based in own peers capabilities. The fts is designed to organise a small set of peers to store portions of the multimedia files statically in a buffer called the altruist buffer. The clients that make up the distributed backup collaborate in system fault tolerance mechanism by reserving buffer space and upload bandwidth capacity; the selected peers form a fault tolerance group (ftg). results show that the control mechanism has great impact over the system and demands a caution design; the proposed fault tolerance scheme collaborates to reduce the overhead imposed on the system and is able to achieve low response times in dealing with failures; this improves user experience by reducing start-up delays and guarantees a better usage of buffer resources. The fts also distributes the control tasks providing reliability and robustness to the vod system.
Datos académicos de la tesis doctoral «P2p-vod on internet: fault tolerance and control architecture«
- Título de la tesis: P2p-vod on internet: fault tolerance and control architecture
- Autor: Rodrigo Godoi
- Universidad: Autónoma de barcelona
- Fecha de lectura de la tesis: 23/07/2009
Dirección y tribunal
- Director de la tesis
- Porfidio Hernández Budé
- Tribunal
- Presidente del tribunal: Ana María Ripoll aracil
- inmaculada Garcia fernandez (vocal)
- (vocal)
- (vocal)