 Copyright 2005 Digital Enterprise Research Institute. All rights reserved. WSLA Language Specification WSMO Working Group Presentation Adina Sirbu & Ioan Toma 18 January 2006

2 Presentation Overview Short recap of WSLA Framework WSLA Language –Parties –Service definition –Obligations Conclusions

3 Short recap of WSLA

4 WSLA Language An XML-based language used by both service providers and consumers

5 Parties Signatory parties: –Service provider –Service consumer Supporting parties: –Measurement –Management –Condition evaluation

6 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

7 Service Definition - SLA Parameter

8 Service Definition - Metric

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10 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

11 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

12 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

13 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 ( –WSMX -> the negotiation component