Angels
in the Cloud
People:
Overview:
Content distribution is and will be a
dominant factor in the field of Network Architecture. The introduction of cloud
computing makes it all the more important. This project aims at providing a
content acceleration service from the cloud. Content Providers will contract
our service to enssure an SLA of content delivery to
its clients. We achieve that through (1) choreographing the P2P connectivity of
clients in a near optimal way and by (2) supplementing the gap between the
average upload capacity and the average download capacity of clients using
angels.
Angels are unique nodes, instantiated from the cloud. They
are not seeders (having the entirety of the file) or clients (desiring to
download the entirety of the file). They download a mere fraction of the file
and upload it to as many clients as possible. The idea is not to waste precious
upload capacity in downloading the whole file to angels, but just the right
amount to fully utilize the angels.
Subprojects:
·
Peer-Assisted
Bulk-Synchronous Content Distribution Service
Bulk Synchronous Content
Distribution is when no clients can start utilizing the data until all the
clients finish downloading it. Many barrier applications can utilized
a content acceleration service like ours. For example; enterprise-wide system
administration requiring synchronous software patching or data replication,
virtual community games and simulated reality environments requiring common
content such as terrain information to be accessible to all players before any
progress could be made, publish-subscribe networks and distributed data stores
requiring consistency across multiple sites, among many others.
·
Raymond
Sweha, Vatche Ishakian and Azer Bestavros. “Angels In
The Cloud: A Peer-Assisted Bulk-Synchronous Content Distribution Service”,
2010 IEEE CLOUD 2011.
·
Raymond
Sweha, Vatche Ishakian and Azer Bestavros. “Angels In The
Cloud: An On-Demand Peer-Assisted Content Distribution Cloud Service”, Winner
of the BU Award for Applied Science, Science and Engineering Research Day, 2010
·
Sweha,
Raymond. Angels: In-Network Support For Minimum Distribution Time in P2P
Overlays (MA
Thesis), August 6, 2009
·
AngelCast: Cloud-based Peer-Assisted Live Streaming Using Optimized Multi-Tree
Construction
Increasingly, commercial content
providers (CPs) o er
streaming and IPTV solutions that leverage an underlying peer-to-peer (P2P) stream
distribution architecture. The use of P2P protocols promises significant
scalability and cost savings by leveraging the local resources of clients specifically,
uplink capacity. A major limitation of P2P live streaming is that playout rates are constrained by the uplink capacities of
clients, which are typically much lower than downlink capacities, thus limiting
the quality of the delivered stream.
Thus, to leverage P2P architectures
without sacrificing the quality of the delivered stream, CPs
must commit additional resources to complement those available through clients.
In this paper, we propose a cloud-based service AngelCast
that enables CPs to elastically complement P2P
streaming as needed". By subscribing to AngelCast,
a CP is able to deploy extra resources (angels), on-demand from the cloud, to
maintain a desirable stream (bit-rate) quality. Angels need not download the
whole stream (they are not leachers), nor are they in
possession of it (they are not \seeders"). Rather, angels only relay (download
once and upload as many times as needed) the minimal possible fraction of the
stream that is necessary to achieve the desirable stream quality, while
maximally utilizing available client resources.
We provide a lower bound on the
minimum amount of angel capacity needed to maintain a certain bit-rate to all
clients, and develop a fluid model construction that achieves this lower bound.
Realizing the limitations of the fluid model construction; namely, susceptibility to potentially
arbitrary start-up delays and significant degradation due to churn. We present
a practical multi-tree construction that captures the spirit of the optimal
construction, while avoiding its limitations. In particular, our AngelCast protocol achieves near optimal performance (compared
to the fluid-model construction) while ensuring a low startup delay by
maintaining a logarithmic-length path between any client and the provider, and
while gracefully dealing with churn by adopting a flexible membership
management approach. We present the blueprints of a prototype implementation of
AngelCast, along with experimental results confirming
the feasibility and performance potential of our AngelCast
service when deployed on Emulab and PlanetLab.
Publications:
• Raymond Sweha, Vatche Ishakian and Azer Bestavros. “AngelCast: Cloud-based
Peer-Assisted Live Streaming Using Optimized Multi-Tree Construction.” ACM MMSys 2012.
Source code:
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