Web Service Reputation: Conceptual Model

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Web Service Reputation Conceptual Model
Presentation on November 26th 2008 Team
Members Sowmya J.Bandalli Karen Doore Preeti
GaneshMohan Title Conceptual Model of Web
Service Reputation Authors E. Michael
Maximilien IBM and NCSU maxim_at_us.ibm.com Munind
ar P. Singh North Carolina State
University singh_at_ncsu.edu URL
http//delivery.acm.org/10.1145/640000/637417/p36
-maximilien.pdf?key1637417key20037377221collG
UIDEdlGUIDECFID12837775CFTOKEN70178819
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Web Service Reputation Conceptual Model

• A Web service represents a set of functions
  addressing a particular domain.
• Web Service Attributes
• Generic Attributes
• Domain Specific Attributes
• Reputation of a web service
• Is a function of a web service that depends on
  attributes
• It depends on the relative importance of each
  attribute with respect to the agent using the
  service.

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Web Service Reputation Important Factors

• Relative Weights given to attributes
• Dependant on Agent Biases, Dependant on Specific
  Domain
• Attribute Aggregation Algorithm
• Simple Majority, Other Algorithms
• Endorsers of the Service
• Trust level of Endorsers
• History of Service
• Services that are new wont have as many
  endorsers
• Older services have more history data
• Dampening Factors for Ratings
• Allows a web services reputation to increase
  with improved service
• More recent activity matters more than old
  activity

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WASP Web Service Agent Proxy
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Conceptual Model UML Static Model Figures
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• A Web Service has 1 associated Reputation for an
  agent considering the service
• A Reputation of a service is a vector of
  attribute values
• A Reputation is determined by a reputation
  algorithm that aggregates attributes that are
  selected to be considered by the agent.
• A Reputation is also affected by a History, that
  keeps previous ratings for a particular service
• The rating for a particular service is determined
  for a particular principal (agent) using the
  RatingAlgorithm which takes into consideration
  the agents bias about the relative importance of
  each attribute.
• Endorsements by other Principals (agents) are
  also considered for determination of Reputation,
  the weighting given to an endorsement is
  dependant on the trust level of the Principal
  giving the endorsement.

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Attributes Model
Domain are collections of attributes for a
specific type of service Cross-Domain
attribute Domain specific attribute
Attributes Each Attribute has a range, or
set of allowed values can be integer,
percentage, Boolean, etc. Relative Weight of
an Attribute Relative to Domain User
preferences Characteristic function from
Attribute value to Rating S-shaped lower
threshold and upper saturation level Monotonicall
y Increasing Step-wise function Temporal
Characteristic Decaying value of an attribute
Example travel delay, if a plane is delayed 10
minutes is tolerable, however a delay of 45
minutes may be intolerable because it causes
problems with connecting flights.
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Generic and Domain Specific Attributes
Web Service Attribute Domains For Web services
that provide similar services, they will share
common attributes, perhaps weighted differently
For different domains. Example Car rental
service Domains Travel Price,
Flexibility of Reservation Changes Retail
Price, Inventory Flexibility of Reservation
Changes may be used by some services to
differentiate their service. Determining
Attributes for a Domain Suggestion let the
attributes for a domain be determined by
community of users and providers for each
domain. Ideally, want a system where new
attributes can be added to domains, and where
services can distinguish themselves by focusing
on certain attributes. So that service doesnt
need to have values for all attributes.
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Conceptual Model Web Services Agent Proxy
Client Desires Service Client uses WSAP to
access web services. Web Services Agent Proxy
Consults with outside registries, reputation
and endorsement agencies to find an appropriate
provider of a desired web service. WSAP can use
information about the users priorities with
information in the form of reputation attributes
and endorsements to determine the service which
is optimum for the client. The WSAP can
provide feedback to the reputation and
endorsement agencies based on the WSAP and user
experience to keep reputation and endorsement
data up to date.