G'R' Gangadharan1, HongLinh Truong2, Martin Treiber2, Vincenzo DAndrea1, Schahram Dustdar2, Renato I

1
Consumer-specified Service License Selection and
Composition

• G.R. Gangadharan1, Hong-Linh Truong2, Martin
  Treiber2, Vincenzo DAndrea1, Schahram Dustdar2,
  Renato Iannella3, Michael Weiss4
• truong_at_infosys.tuwien.ac.at
• 1University of Trento, Italy
• 2Vienna University of Technology,
  Austria3National ICT Australia, Austrilia
• 4Carleton University, Canada

2
Talk outline

• Motivation
• ODRL-S license overview
• License-aware service selection and composition
  framework
• License composition for composite service
• Directional Matchmaking Algorithm
• Illustrating scenario
• Conclusion and next steps

3
Software as a Service/Utility License

• Web service, SaaS and Service Utility
• Can be composed and used by different consumers
• Different usage modes (e.g., subscription, pay
  per use)
• etc.
• Some questions
• How to deal with legal terms? Such as
  noncommercial use
• How to associate licenses with a service utility?
• How to search, select and compose service
  utility, taking into account the license?

4
What is a Service License?

• A license between a service provider (as the
  licensor) with (could be) many service consumers
  (the licensees).
• Describes the use of and access to services in
  machine interpretable form.
• A complementary concept for completeness of
  service usage description.
• Can be viewed as a superset including SLAs and
  Policies.

5
Existing work in Service License?

• Though there are few examples of service
  licenses (by Amazon, Google, Yahoo!), to the best
  of our knowledge, there is no conceptualization
  of service licensing.
• These licenses are not machine interpretable.

6
Why Not a Software License for Services?

• Services are also software fragments!
• Services are not targeted as standalone
  applications.
• Consumers do not require to download them for
  local use.
• Services support composition and reuse.

7
What is this paper about

• This paper
• Uses ODRL-S to describe service license
• Proposes composition and selection of services
  based on licenses
• We do not discuss
• The comparison between ODRL-S with other
  specifications (e.g., WS-Policy, WSPL, WSOL,
  WSLA, Slang, etc.)
• Specifying license is not the focus of this paper
• See http//dit.unitn.it/gr/pubs.html
• Selecting a service based on functional
  parameters
• Contribution Consumer-specified license-based
  service selection

8
Background Anatomy of a Service License

• ODRL-S (Open Digital Rights Language for
  Services)
• Based on ODRL-S (http//odrl.net/)
• Subject
• define the service being licensed
• Scope of Rights
• adaptation, composition, attribution,
  derivation, sharealike, non-commercial use
• Financial Terms
• Warranty, Indemnity, and Limitation of liability
  (WIL)
• Evolution
• deal with software evolution/versioning

9
Background ODRL-S Service License Model
Subject
ODRL Asset Model
Scope of Rights
ODRL-S is nominated by the ODRL consortium as a
standard for representing service licensing and
currently open for public review at a Working
Group (ODRL-S WG).
Extended ODRL Rights Model
Financial Terms
Representation of SLA in ODRL
Warranties, Indemnities, Limitation of
Liabilities
Representation of Service Evolution in ODRL
Evolution
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Background ODRL-S Service License Structure

• lto-exoffergt
• lto-exassetgt
• lto-excontextgt
•   lto-dduidgturnservice-idlt/o-dduidgt
•  lt/o-excontextgt
•  lt/o-exassetgt
• lto-expermissiongt
•   ltslderivation /gt
•  lt/o-expermissiongt
• lto-exrequirementgt
•  lto-ddattribution /gt
• lto-ddperusegt
• lto-ddpaymentgt
•   lto-ddamount o-ddcurrencyEURgt
  1.00lt/o-ddamountgt
•   lt/o-ddpaymentgt
• lt/o-ddperusegt
• lt/o-exrequirementgt
•  lt/o-exoffergt
• lt/o-exrightsgt

Model
Element
Attribute Name
Element Value
Attribute Value
11
Previous and background work for this paper

• License Compatibility analysis ICSOC07.
• Service selection based on functional parameters
• Vector space-based web services search
  (http//www.vitalab.tuwien.ac.at/projects/search/)
  
• Web Services Evolution Management Framework
  (SEMF)
• Managing licenses and other services information
• https//www.vitalab.tuwien.ac.at/autocompwiki

ICSOC07 G.R.Gangadharan, M.Weiss, V.DAndrea,
R.Iannella Service License Composition and
Compatibility Analysis, Proc. of the Intl.
Conf. on Service Oriented Computing (ICSOC07),
Vienna, Austria, Sept. 2007.
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License-aware Service Composition Framework
User interface, Web services consumers
Functional parameterslicense clauses
Services and licenses
Service Evolution Management Framework (SEMF)
Service Selection Request Handler
Functional parameters
Compatible services license links
Compatible license
License clauses and links
FCA (Function Compatibility Analyzer)
LCA (License Compatibility Analyzer)
Service Discovery
Resource Management
Service Information
13
Managing Service License using SEMF

• ltfeed xmlns"http//www.w3.org/2005/Atom"gt
• ltidgturnuuid3043abca-90a5-45d4-8508-bbaa4945f
  fadlt/idgt
• ltentrygt
• ltidgturnuuid121f3368-aea8-4197-86b0-f0561
  a428042lt/idgt
• ltupdatedgt2007-09-14T1637530200lt/update
  dgt
• ltpublishedgt2007-09-14T1637530200lt/publ
  ishedgt
• lttitlegtLicencelt/titlegt
• lt!-- link to current information --gt
• ltlink href"http//wisur.at8080/axis/
• /services/WISIRISFuzzySearchService?od
  rls"/gt
• ltcategory term"License"
• scheme"http//www.dmoz.org/Computers/
  
• Software/Licensing/"/gt
• ltcategory term"http//odrl.net/1.1/ODRL-
  EX-11.xsd"/gt

ODRL-S License
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Managing Service License using SEMF (cont.)

• .
• ltcontent type"applicationxml"gt
• ltagreementgt
• ltassetgt
• ltexecutegt
• ltrequirementgt
• ltperusegt
• ltpaymentgt
• ltamount currency"EUR"gt1.00lt/amountgt
• lttaxpercent code"VAT"gt20.0lt/taxpercentgt
• lt/paymentgt
• lt/perusegt
• lt/requirementgt
• lt/executegt
• lt/assetgt
• lt/agreementgt
• lt/contentgt

15
Managing Service License using SEMF (cont.)
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Consumer-specified Licenses

• A service provider defines a license for the
  service and publishes the service with the
  license.
• Service consumers are often interested in
  selecting a service with a particular type of
  license.
• Consumer-specified license A set of license
  clauses specified by a consumer to be used in the
  selection of services.

17
Consumer-specified License-based Service
Selection and Composition

• Consumers specify licenses for a service to be
  composed
• Our framework
• Finds suitable services
• Checks if licenses allow services to be composed
• Proposes composite service license
• Applies Directional Matching Algorithm for
  consumer-specified and provider-specific licenses
  in license composition

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Service License Composition

• Objective
• To propose a service license for composite
  service
• Composite license associated with composite
  service
• Approach
• Two licenses are compared using our algorithm
  presented in ICSOC07.
• A composite service license is generated by
• Extracting elements of each license and put them
  together in a single license.
• Removing redundant clauses.

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Service License Composition

• A set of functionalities and the requested
  license clauses are provided by a consumer as
  inputs.
• Services matching the functionality specified by
  a consumer is retrieved.
• LCA searches in the Service Information for the
  information about licenses of each service being
  selected by FCA
• The license of the selected service is compared
  with the consumer-specified license.

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Service License Composition Algorithm

• Find all services to be composed that functional
  parameters met consumer-specified license clauses

• Licenses of all services to be composed must be
  compatible

• Compose a license for composite service
• Directional Matching Algorithm

21
Directional Matchmaking Algorithm (DMA)

• Analyzing the compatibility between a consumer
  specified license and a provider specified
  service license.
• Compatibility is directional
• Based on a set of rules for compatibility between
• consumer-specified license clauses against
  unspecified Scope of Rights and Financial Terms
  in provider-specified license clauses.
• unspecified Scope of Rights and Financial Terms
  in consumer-specified license clauses against
  provider-specified license clauses.

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Directional Matchmaking Algorithm (DMA) (cont.)

• Two licenses are compatible, if all the
  respective models in both the licenses are
  compatible.
• A model is compatible with another model, if the
  model types are same and their elements are
  compatible.
• An element e1 is compatible with another element
  e2, if
• e1 and e2 have same type or
• using redefinition or unspecification use
  tables
• e1 and e2 have equal value.
• for all nested elements, corresponding elements
  are compatible.
• all attributes of e1 and e2 are compatible.
• An attribute a1 is compatible with another
  attribute a2, if the attributes are of same type
  and the associated values of attributes are equal.

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Illustrating scenario

• Current implementation
• Not all features have been implemented
• Java-based algorithms
• Tested in house
• Simple scenario
• RestauranceService to be composed from
• LocationService provides map/location
  information
• ReservationService provides table reservations
• We need to find possible LocationService and
  ReservationService suitable to consumer-specified
  license

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Illustrating scenario examples of licenses
Consumer-specified license
ReservationService License
LocationService License
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Illustrating scenario Consumer Specified SL
Composition
LocationService License
ReservationService License
lto-expermissiongt ltslderivation/gt lt/o-expermis
siongt
lto-expermissiongt ltslcomposition/gt lt/o-expermi
ssiongt
Compatible
Compatible
lto-expermissiongt ltslcomposition/gt lt/o-expermi
ssiongt
Consumer-Specified Service License
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Illustrating scenario Consumer Specified SL
Composition
LocationService License
lto-expermissiongt ltslcomposition/gt lt/o-expermi
ssiongt
Compatible
lto-expermissiongt ltslderivation/gt lt/o-expermis
siongt
ReservationService License
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Illustrating scenario Resulting Composite
Service License
lto-exoffergt lto-expermissiongt
ltslcomposition/gt lt/o-expermissiongt
lto-exrequirementgt lto-ccattribution/gt
lt/o-exrequirementgt lto-exrequirementgt
lto-ccsharealike/gt lt/o-exrequirementgt
lt/o-exoffergt
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Summary and next challenges

• Mechanism to specify and associate licenses with
  services
• To support consumer-specified, license-aware
  service selection and composition, motivated by
  SaaS and service utility models
• Foundation study for our next steps
• How to realize and provide a full implementation
  of service license model for SaaS/service utility
  
• Validation of a real system with license-aware
  selection and composition
• License enforcement for services

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Thanks for your attention!Feedback, suggestion,
research collaboration are more than welcome!

• Hong-Linh Truong
• Distributed Systems GroupVienna University of
  Technology
• truong_at_infosys.tuwien.ac.athttps//www.vitalab.tu
  wien.ac.at/autocompwiki