On-demand streaming service has recently gained an intensive consideration due to its promising usage in a rich set of Internet-based services, such as video-on-demand, distance learning, media distribution. However, there are still many challenges towards building an efficient, scalable and reliable on-demand streaming system over Internet. The main goal of GridCast is to provide a cost-efficient video-on-demand streaming service with better user experience and higher scale.
What is GridCast
GridCast is a peer-to-peer video-on-demand system, comprised of eb portal, tracker server, source server and peers. In GridCast, we propose a novel ring-assisted overlay management scheme, called RINDY. In RINDY, each peer maintains a set of concentric rings with power law radii and places all neighbors on these rings according to their distances. More specifically, near neighbors with overlapped buffer windows with current node are placed on the inn ermost ring as backup data suppliers; while some randomly sampled remote neighbors are placed on the outer rings as routers to nodes with playing positions specified by VCR operations. Under this scheme, a peer only needs O(log (T/w)) hops (where T is the total time length of the video stream and w is the buffer window size of peers) to identify and connect to a new group of peers close to the destination playing positions specified by random seeking operations. RINDY has the following features: first, it inherits good reliability from the random gossip protocol in mesh-based overlay; second, peers look for neighbors only from local rings, thereby avoiding the load imbalance problem of tree-based overlays; third, the remote neighbors provide a bridge to efficiently find new desired neighbors after random seeking.
GridCast is deployed since May 2006 and has attracted more than twenty thousand users and supported up to hundreds of concurrent users at the peak time with one source server, which has 100Mb bandwidth, 2GB Memory and 1TB disk. During the popular 2006 FIFA WORLD CUP event, it provided VoD service for users in 6 provinces in China. The majority of users are students with Internet services supplied by CERNET.
Check out some sites currently using GridCast.