Mathematical Problems in Engineering
preference through comparing the users’ ranking similarity of
thecommonlyinvokedservicesandthenmakesQoSranking
prediction of a set of cloud services for the target user based
on the similar users’ ranking with him.
To eliminate a sharp trust crisis between cloud consumers
and cloud service providers, trust is introduced in the process
of service selection. In [], a novel cloud service-compo-
sition method based on the trust span tree was proposed.
roughthecrediblerelationshipevolution,thetrustunion
of service providers with same or similar function is formed,
which helps to exclude uncertain or malicious service from
the trust span tree. But trust is a subjective cognition judg-
ment. erefore, the trust evaluation needs not only objective
measurement but also subjective perception. Ding et al. []
designed a novel framework named CSTrust for conducting
cloud service trustworthiness evaluation by combining QoS
prediction and customer satisfaction estimation. To reduce
thebiascausedbyunreasonablefeedbackfromunprofes-
sional or malicious cloud users, a method was proposed for
ltering the feedback from such users in []. Aer process-
ing, the aggregated result can quantitatively reect the overall
quality of a cloud service.
Whether a service is credible to satisfy the consumer’s
personalitypreferenceornotisthemainconsideration
in []. is paper utilized fuzzy clustering technology to
classify services by the requesters’ preferences and gave a
service selection algorithm to select a closest classication
with the requester’s preference. With the integration of trust
evaluation method and CF technique, Wang and Zhang
[] presented a trustworthy service selection model based
on collaborative ltering. is model introduces consumer
correlation to embody the impact of the requester’s personal
characteristics on selection process, computes creditability
of recommendation, and employs analytic hierarchy process
to decide the weight of each factor in service reputation.
Abedinzadeh and Sadaoui [] presented ScubAA, a novel
generic agent trust management framework based on the the-
ory of human plausible reasoning. ScubAA recommends to
the user a list of the most trusted services in terms of a single
personalized value derived from several types of evidences
such as user’s feedback, history of user’s interactions, context
of the submitted request, references from third party users as
well as from third party service agents, and structure of the
society of agents.
As seen from the above literatures, selecting the appropri-
ate recommendation users is the key to the service selection
basedontrust.In[], an innovative idea for selecting the
reliable recommendation users was explored. e authors
thought that sparsity, cold-start and trustworthiness were
major issues challenging service recommendation in adopt-
ing similarity-based approaches. With the prevalence of
social networks, to a certain extent, the user’s characteristics
andpreferencewereexposedfromthedatainblogsand
social-networking sites. So a social network-based service
recommendation method with trust enhancement was pro-
posed in the paper. e method assesses the degree of trust
between users in social network by a matrix factorization, and
then recommendation results are obtained by an extended
random walk algorithm.
e above literatures used dierent technologies to realize
an intelligent service selection for consumers from dierent
angles, including quantifying the consumers’ demands or
preferences, predicting the quality of service, matching the
consumer’s demands and the service’s performance, and
recommending the services based on trustworthy consumers.
Dierent methods have dierent merits and limitations.
Firstly, the method based on the parameters matching
between the consumer’s demands and the service’s perfor-
mance is relatively simple and intuitive. But this type of
the method mostly requires the consumers to explicitly give
his/her QoS demands, which is too dicult for consumers to
provide these parameters. So its feasibility is poor in practice.
Secondly, the method by predicting the quality of service only
considers the general performance of the service but ignores
the dierences of QoS demands. irdly, the fuzziness and
uncertaintyofuserpreferenceimplythatitisadicultthing
tominetheusers’preferences.emethodsofquantifying
the consumers’ preferences are still under study. In addition,
there are still no ecient ways to validate the quantitative
results. Finally, the method based on trust recommendation
is now widely accepted in the eld of electronic commerce
and social networking service. us the method has good
application prospects in terms of cloud services selection.
e key problem of the method is the choice of trustworthy
customers for service recommendation. But the existing
methods for selecting the trustworthy customers are mostly
unstableandinecient,whichaecttheaccuracyofthe
selection results and the feasibility of the selection process.
From what has been discussed above, we can see clearly
that the core problem of service selection is to nd a
feasible method to identify dierent consumers’ preferences.
To resolve the problem, a cloud service selection model
basedonsimpleevaluationinformationandtheideaof
the trust in community network will be built in the paper.
At rst, we need to consider how to mine the consumers’
preferences based on available information in the cloud so
as to improve the feasibility of the method in practical
application. Inspired by the literature [], a consumer is a
mappingforarealpersoninrealsociety,whosebehaviorand
preference are relatively stable. Due to dierent profession
and background, the preferences of the consumers would
show some group features. So we can cluster the consumers
with similar preference to form a stable community, which
is the basis of service selection. According to the theory of
human plausible reasoning [], the consumer would trust
the consumers who are similar with him/her more than the
others. en we design a service selection model based on
community trust.
3. Community Discovery Model Based on
Consumer Preference
Predicting a consumer’s evaluation on an unknown service
mainly relies on the recommendations from other con-
sumers. So whether other consumers’ evaluations on a target
serviceareworthytotrustornotwillhavealargeimpacton
the accuracy of prediction. erefore it is a key step to nd
the trusted recommendation users in the process of service