Copyright 2005 Digital Enterprise Research Institute. All rights reserved.
www.deri.org
WSLA Language Specification
http://www.research.ibm.com/wsla/
WSMO Working Group PresentationAdina Sirbu & Ioan Toma
18 January 2006
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Presentation Overview
• Short recap of WSLA Framework• WSLA Language
– Parties– Service definition– Obligations
• Conclusions
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Short recap of WSLA
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WSLA Language
• An XML-based language used by both service providers and consumers
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Parties
• Signatory parties:– Service provider– Service consumer
• Supporting parties:– Measurement– Management– Condition
evaluation
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Service Definition – Service Object
• A ServiceObject is an abstraction of all conceptual elements for which SLA parameters and the corresponding metrics can be defined
• A ServiceObject includes any number of: Schedules, Triggers, Constants, MetricMacroDefinition, MetricMacroExpansion, SLAParameters and Metrics
• ServiceDefinition, Operation and OperationGroup are all subtypes of ServiceObject
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Service Definition - SLA Parameter
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Service Definition - Metric
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Service Definition - Metric
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Obligations
Service Level Objective
Elements:• the obliged party• one or more validity
periods• the state = a logical
expression• an evaluation event
or an evaluation schedule
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Obligations
Action Guarantee
Elements:• the obliged party• the precondition = a
logical expression• an evaluation event
or an evaluation schedule
• the qualified action• the execution
modality
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Obligations
Logic Expressions:• “follow first-order logic”• contain AND, OR, NOT,
IMPLIES operators which connect predicates or, again, expressions
• could be extended e.g., to contain variables and quantifiers
Predicates:• can have SLA parameters and
scalar values as parameters • new domain-specific predicates
are introduced by extending the abstract predicate type
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Conclusions & Relevance to WSMO/L/X
• Conclusions– WSLA allows to express: what to measure, how to measure,
who does what and guarantees– WSLA Language – a XML based language for specifying SLAs
related information
• Relevant for:– WSMO -> describe semantically the services of WSLA
framework (measurement, evaluation, management)
-> QoS representation, reasoning, measurement – WSMT -> the monitoring part (
www.alphaworks.ibm.com/tech/ettk)– WSMX -> the negotiation component