02-08-2013, 04:56 PM
Social Cloud Computing: A Vision for Socially Motivated Resource Sharing
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Abstract
Online relationships in social networks are often based on real world relationships and can therefore be used to infer a level
of trust between users. We propose leveraging these relationships to form a dynamic “Social Cloud,” thereby enabling users to share
heterogeneous resources within the context of a social network. In addition, the inherent socially corrective mechanisms (incentives,
disincentives) can be used to enable a cloud-based framework for long term sharing with lower privacy concerns and security
overheads than are present in traditional cloud environments. Due to the unique nature of the Social Cloud, a social market place is
proposed as a means of regulating sharing. The social market is novel, as it uses both social and economic protocols to facilitate
trading. This paper defines Social Cloud computing, outlining various aspects of Social Clouds, and demonstrates the approach using
a social storage cloud implementation in Facebook.
INTRODUCTION
IGITAL relationships between individuals are becoming
as important as their real world counterparts. For
many people social networks provide a primary means of
communication between friends, family, and coworkers.
The increasing ubiquity of social network platforms is
evidenced by their rapid and ongoing growth. For instance,
Facebook has over 500 million active users of which
50 percent log on every day.1
Users are more likely to trust information from a “friend”
if the digital relationship between the two is based on a real
world relationship (friend, family, colleague) rather than a
purely online relationship (second life, online games, etc.).
As relationships within online social networks are at least
partly based on real-world relationships, we can therefore
use them to infer a level of trust that underpins and
transcends the online community in which they exist.
SOCIAL CLOUD COMPUTING
The act of adding an individual as a social network “friend”
implies that a user has some degree of knowledge of the
individual being added. Such connectivity between indivi-
duals can be used to infer that a trust relationship exists
between them. However, it does not describe the level of
trust or the context of the relationship. For instance a
“friend” can be a member of the family, a work colleague,
a college affiliate, a member of the same sports club, etc.
Facebook has recently recognized the need for the
creation of such groups and allows users to differentiate
between, for example, close friends and colleagues. In a
Social Cloud, this provides the basis for defining different
levels of trust based on the group abstraction supported by
the infrastructure. For example, a user could limit sharing
with close friends only, friends in the same country,
network or group, all friends, or even friends of friends.
Trust and Risk
Commercial cloud providers typically offer few explicit
guarantees, instead they rely on implied trust based on the
commercial standing of the provider. For the individuals
sharing resources within a Social Cloud this approach is not
feasible, and therefore it is important to use social incentives
and the underlying real world relationships as a substitute
foundation for trust. At present, none of the major social
networks are able to provide guarantees about the real-
world identity associated with a user profile. To do so,
explicit identification processes, such as those used in
Safebook [2], are required to ensure profiles are mapped to
a real person or organization.
Motivation for Contribution
The underlying social incentives present in a Social Cloud
motivate users to participate in, and contribute to, their
community in different ways. Motivation has been studied
in a number of other online domains [3], for example,
sharing information and photos in social networks, sharing
metadata and tags in online communities, and collaborative
knowledge building through online content projects (e.g.,
Wikipedia) or open source software projects. Motivation is
generally categorized as either intrinsic or extrinsic.
Facebook Applications
Facebook exposes access to their social graph through the
OpenGraph API,3 through the Representational State
Transfer (REST) service interface applications can access
all objects (friends, events, groups, application users, profile
information, and photos) and the connections between
them. To access the OpenGraph API both the user and the
application must be authenticated, in Facebook this process
uses the OAuth protocol [38]. The Facebook user and
application authorization model was one of the motivating
factors for choosing Facebook.
Currency Regulation
The social storage cloud includes a credit-based system that
rewards users for contributing resources and charges users
for consuming resources. A banking service registers every
member of the cloud by storing their credit balance and all
agreements they are participating (or have participated) in.
Credits are exchanged between users when an agreement is
made, prior to the service being used. To bootstrap
participation in the Social Cloud, users are given an initial
number of credits when joining the cloud. While suitable for
testing, this initial credit policy is susceptible to inflation
and cheating (if fake users are created and the initial credits
are transferred). Currently, there is no mapping between
Social Cloud credits and real currencies or Facebook credits.
The banking service is composed of two associated
context services each representing different instance data.
The first context service manages user resources while the
second manages storage agreements. The user resource
stores the user’s Facebook ID, current credits, agreement
IDs the user has participated in, and auction references. The
agreement resource contains any agreements created in the
system, which is used to manage provision information and
act as a receipt.
Posted Price Allocation
Posted price trading requires several steps: identification of
storage requirements, generation of an SLA, instantiation of
a storage service, and registration of the transaction with
the banking service. The time taken to perform these
operations is constant and generally small compared to the
time taken to discover storage offers, which is dependent
on the MDS service.
Fig. 9 shows the time taken to query MDS for an
increasing number of registered entries. The time includes
the cost of converting the XML result into a Java object.
Registration performance is shown to be dependent on the
amount of memory given to the container and the number
of registered entries. With 1 GB of memory over 2,000 offers
can be retrieved in less than 2 seconds. Therefore, MDS can
be run even on a low specification server yet still support a
Social Cloud and its market.
REFLECTIVE ANALYSIS
The social storage cloud provides a first step toward
realizing the vision of Social Cloud computing. In parti-
cular, it provides an integrated platform on which social
network friends can trade a single resource (storage) with
one another using a credit model. The cloud model was
shown to be well suited to this type of scenario as users are
able to lease capacity through standardized service-based
interfaces using an abstracted virtualized resource layer.
This section discusses how the social storage cloud fulfils
the high-level vision of Social Cloud computing.
The relationships and policies represented in the social
storage cloud are one dimensional, in that all friends are
treated equally. At present all users belong to the same
group and there is no ability to define different sharing
policies based on relationship type. The architecture is able
to select users based on their friend relationship and could
be extended to retrieve users based on their group
membership or relationship type. The evaluation showed
the cost of friend selection in MDS to be low for moderately
sized Social Clouds. Simple policies are supported in the
auction scenario to alter the bid price based on the identity
of the requester.
CONCLUSION
This paper has presented the vision of Social Cloud
computing, an amalgamation of cloud computing and
social networking. A Social Cloud is unique in that it
builds upon the social incentives and external real-world
relationships inherent in social networks to provide
heterogeneous resource trading. This work represents a
novel approach to collaborative computing utilizing so-
cially corrective mechanisms to motivate contribution and
compliance without requiring extensive incentive and
enforcement architectures.
A Facebook-based social storage cloud has been devel-
oped and deployed. The social storage cloud supports
storage trading through a two protocol social marketplace.
The integrated social storage Facebook application allows
users to discover and trade storage contributed by their
friends, taking advantage of preexisting trust relationships.
A credit-based trading approach has been adopted to
discourage free loading.