Towards Consumer-specified Service License selection and Composition

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G.R. Gangadharan1, Hong-Linh Truong2, Martin Treiber2, Vincenzo D‘Andrea1, Schahram Dustdar2,

Renato Iannella3, Michael Weiss4

[email protected]

1University of Trento, Italy 2Vienna University of Technology, Austria

3National ICT Australia, Austrilia4Carleton University, Canada

Consumer-specified Service License Selection and Composition

7th IEEE ICCBSS, 25-29 Feb 2008, Madrid

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


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?


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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.


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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.


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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.


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


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•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

Background: Anatomy of a Service License


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Subject

Scope of Rights

Financial Terms

Warranties, Indemnities, Limitation of Liabilities

Evolution

ODRL Asset Model

Extended ODRL Rights Model

Representation of SLA in ODRL

Representation of ServiceEvolution in ODRL

Background: ODRL-S Service License Model


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).

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Element Value

Background: ODRL-S Service License Structure

<o-ex:offer> <o-ex:asset> <o-ex:context> <o-dd:uid>urn:service-id</o-dd:uid> </o-ex:context> </o-ex:asset> <o-ex:permission> <sl:derivation /> </o-ex:permission> <o-ex:requirement> <o-dd:attribution /> <o-dd:peruse> <o-dd:payment> <o-dd:amount o-dd:currency=“EUR”>

1.00</o-dd:amount> </o-dd:payment> </o-dd:peruse> </o-ex:requirement> </o-ex:offer></o-ex:rights>

Model

Attribute Name

Element

Attribute Value


Previous and background work for this paper

License Compatibility analysis [ICSOC’07]. 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

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[ICSOC’07] G.R.Gangadharan, M.Weiss, V.D’Andrea, R.Iannella “Service License Composition and Compatibility Analysis”, Proc. of the Intl. Conf. on Service Oriented Computing (ICSOC’07), Vienna, Austria, Sept. 2007.


Service Evolution Management Framework (SEMF)12

License-aware Service Composition Framework


User interface, Web services consumers

Service Selection Request Handler

FCA (Function Compatibility Analyzer)

LCA (License Compatibility Analyzer)

Service Discovery Resource Management

Service Information

Functional parameterslicense clauses

Services and licenses

Functional parameters Compatible services

license linksLicense clauses and links

Compatible license

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<feed xmlns="http://www.w3.org/2005/Atom">

<id>urn:uuid:3043abca-90a5-45d4-8508-bbaa4945ffad</id>

<entry>

<id>urn:uuid:121f3368-aea8-4197-86b0-f0561a428042</id>

<updated>2007-09-14T16:37:53+02:00</updated>

<published>2007-09-14T16:37:53+02:00</published>

<title>Licence</title>



<link href="http://wisur.at:8080/axis/

/services/WISIRISFuzzySearchService?odrls"/>

<category term="License"

scheme="http://www.dmoz.org/Computers/

Software/Licensing/"/>

<category term="http://odrl.net/1.1/ODRL-EX-11.xsd"/>

ODRL-S License

Managing Service License using SEMF

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….

<content type="application+xml">

<agreement>

<asset>

<execute>

<requirement>

<peruse>

<payment>

<amount currency="EUR">1.00</amount>

<taxpercent code="VAT">20.0</taxpercent>

</payment>

</peruse>

</requirement>

</execute>

</asset>

</agreement>

</content>

Managing Service License using SEMF (cont.)


Managing Service License using SEMF (cont.)


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•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.

Consumer-specified Licenses


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 [ICSOC’07].• 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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• 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.

Service License Composition


Service License Composition Algorithm

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


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• Licenses of all services to be composed must be compatible

Compose a license for composite service

Directional Matching Algorithm

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•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.

Directional Matchmaking Algorithm (DMA)


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• 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.

Directional Matchmaking Algorithm (DMA) (cont.)


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


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LocationService License ReservationService License

Consumer-specified license

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<o-ex:permission> <sl:composition/></o-ex:permission>

<o-ex:permission> <sl:derivation/></o-ex:permission>

<o-ex:permission> <sl:composition/></o-ex:permission>

Consumer-Specified Service License

LocationService LicenseReservationService License

Illustrating scenario: Consumer Specified SL Composition

CompatibleCompatible CompatibleCompatible


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<o-ex:permission> <sl:composition/></o-ex:permission> <o-

ex:permission> <sl:derivation/></o-ex:permission>

LocationService License

ReservationService License

Illustrating scenario: Consumer Specified SL Composition

CompatibleCompatible


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<o-ex:offer> <o-ex:permission> <sl:composition/> </o-ex:permission> <o-ex:requirement> <o-cc:attribution/> </o-ex:requirement> <o-ex:requirement> <o-cc:sharealike/> </o-ex:requirement> </o-ex:offer>

Illustrating scenario: Resulting Composite Service License


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 TruongDistributed Systems GroupVienna University of Technology

[email protected]://www.vitalab.tuwien.ac.at/autocompwiki


Towards Consumer-specified Service License selection and Composition

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