Towards NFC-Aware Process Execution for Dynamic Environments WiVS 2011 Kristof Hamann Sebastian Steenbuck Sonja Zaplata Distributed Systems and Information Systems Department of Informatics University of Hamburg 10. März 2011
Introduction Description of NFCs Selection Algorithm Conclusion Agenda Problem Statement: Process Execution in Dynamic Environments 1 Description of Non-Functional Requirements and Offers 2 Dynamic Service Selection for NFC-Aware Processes 3 Conclusion 4 Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 2
Introduction Description of NFCs Selection Algorithm Conclusion NFC-driven Service Selection A 3 A 1 A 2 A 5 A 4 Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 3
Introduction Description of NFCs Selection Algorithm Conclusion NFC-driven Service Selection S 1 S 6 S 3 A 3 S 2 A 1 A 2 A 5 S 5 A 4 S 7 S 4 Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 3
Introduction Description of NFCs Selection Algorithm Conclusion NFC-driven Service Selection S 1 S 6 S 3 A 3 S 2 A 1 A 2 A 5 S 5 A 4 S 7 S 4 Definition: Non-Functional Characteristics (NFCs) The NFCs of a service denote all aspects which can be used by clients in order to evaluate service quality (Dobson et al. 2005) Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 3
Introduction Description of NFCs Selection Algorithm Conclusion NFC-driven Service Selection S 1 S 6 S 3 A 3 S 2 A 1 A 2 A 5 S 5 A 4 S 7 S 4 security encryption: AES Definition: Non-Functional Characteristics (NFCs) The NFCs of a service denote all aspects which can be used by clients in order to evaluate service quality (Dobson et al. 2005) Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 3
Introduction Description of NFCs Selection Algorithm Conclusion NFC-driven Service Selection price < 10 S 1 S 6 S 3 A 3 S 2 A 1 A 2 A 5 S 5 A 4 S 7 S 4 security encryption: AES Definition: Non-Functional Characteristics (NFCs) The NFCs of a service denote all aspects which can be used by clients in order to evaluate service quality (Dobson et al. 2005) Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 3
Introduction Description of NFCs Selection Algorithm Conclusion NFC-driven Service Selection price < 10 S 1 S 6 S 3 A 3 S 2 A 1 A 2 A 5 S 5 A 4 S 7 S 4 security encryption: AES General Requirements 1 formal description of the local and global statements 2 algorithm in order to evaluate statements and to find a suitable set of services (optimization is an NP -hard problem!) Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 3
Introduction Description of NFCs Selection Algorithm Conclusion NFC-driven Service Selection price < 10 S 6 S 3 A 3 S 2 A 1 A 2 A 5 S 5 A 4 S 7 security encryption: AES Observations available services and thus their characteristics change very often evaluation has therefore to be done at runtime worst case: step-by-step late binding of services with no possibility for an optimal solution Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 3
Introduction Description of NFCs Selection Algorithm Conclusion NFC-driven Service Selection price < 10 S 3 A 3 S 8 S 2 A 1 A 2 A 5 A 4 S 7 security encryption: AES Observations available services and thus their characteristics change very often evaluation has therefore to be done at runtime worst case: step-by-step late binding of services with no possibility for an optimal solution Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 3
Introduction Description of NFCs Selection Algorithm Conclusion Algorithms for Service Selection: Deriving Requirements Situation in mobile ad-hoc networks relatively small number of available services processes are comparatively short services are not known until the process is executed Requirements of an algorithm low complexity ⇒ heuristic approach rapid detection of a first compatible solution optional delayed optimization consideration of user-defined goals Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 4
Introduction Description of NFCs Selection Algorithm Conclusion Languages for Describing Non-Functional Requirements WSLA WS-Policy WSOL CQML HP Labs Composition – – – – – Levels of quality – + + × ◦ Compliance to standards + + – + ◦ Fine-grained + + + + × Requirements vs. offers + + – ◦ ◦ Priorities – – – – – Syntactical separation + + + + × Refinement + + ◦ ◦ ◦ Generic applicability + – × × × Extensibility + + + – – good: + average: ◦ poor: – not applicable: × Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 5
Introduction Description of NFCs Selection Algorithm Conclusion Meta-Model for Non-Functional Characteristics Service Provider Service Consumer profile P 1 profile C 1 statement p 1 characteristic 1 statement c 1 characteristic 1 statement p 2 characteristic 2 statement c 2 characteristic 2 statement p 3 characteristic 3 profile C 2 service profile P 2 statement c 3 characteristic 1 statement p 4 characteristic 1 statement c 4 characteristic 2 statement p 5 characteristic 2 statement c 5 characteristic 3 statement p 6 characteristic 4 statement c 6 characteristic 4 Figure: based on Aagedal (2001) CQML Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 6
Introduction Description of NFCs Selection Algorithm Conclusion Language Model: Characteristics (numeric) price < 10 S 1 S 6 S 3 characteristic A 3 S 2 A 1 A 2 A 5 S 5 name = price A 4 S 7 S 4 numeric security encryption: AES type = integer direction = decreasing invariant min = 0 compositionBehavior aggregateFunction = sum parallel = false Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 7
Introduction Description of NFCs Selection Algorithm Conclusion Language Model: Characteristics (non-numeric) characteristic price < 10 S 1 S 6 S 3 name = encryption algorithm A 3 S 2 A 1 A 2 A 5 S 5 set A 4 S 7 S 4 elements security encryption: AES member = AES member = DES order simpleOrder element1 = AES orderOperator = < element2 = DES direction = decreasing local = true Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 8
Introduction Description of NFCs Selection Algorithm Conclusion Language Model: Statements price < 10 S 1 S 6 S 3 A 3 S 2 A 1 A 2 A 5 S 5 statement A 4 S 7 S 4 name = pricing security encryption: AES priority = 1 characteristic targetCharacteristic = price numericConstraint max=10 Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 9
Introduction Description of NFCs Selection Algorithm Conclusion Language Model: Profiles wsp:policy wsp:all nfc:statement nfc:name = responseTime . . . nfc:statement nfc:name = rating . . . wsdl:binding wsp:PolicyReference URI=". . . " wsdl:operation . . . Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 10
Introduction Description of NFCs Selection Algorithm Conclusion Overview 1. evaluating local requirements 2. evaluating global requirements 3. optimizing the solution (optional) Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 11
Introduction Description of NFCs Selection Algorithm Conclusion Step 1: Local Requirements 3. optim. 1. local 2. global 1. Evaluating local requirements applies to statements associated with a single activity applies to all characteristics marked as local applies to unordered non-numeric characteristics applies to some other special cases (transforming global requirements into local ones) removes services which do not meet the local requirements price < 10 S 1 S 6 S 3 A 3 S 2 A 1 A 2 A 5 S 5 A 4 S 7 S 4 security encryption: AES Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 12
Introduction Description of NFCs Selection Algorithm Conclusion Step 2: Global Requirements 3. optim. 1. local 2. global root node activity 1 S 1 , a S 1 , b activity 2 S 2 , a S 2 , b S 2 , a S 2 , b activity 3 Goal finding a valid path through the tree as fast as possible Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 13
Introduction Description of NFCs Selection Algorithm Conclusion Step 2: Global Requirements 3. optim. 1. local 2. global root node activity 1 S 1 , a S 1 , b activity 2 S 2 , a S 2 , b S 2 , a S 2 , b activity 3 Purging of Parts of the Tree use knowledge of characteristics: e.g. aggregation function, direction, constraints, . . . derive properties: monotonicity exclude according parts of the tree Towards NFC-Aware Process Execution for Dynamic Environments Kristof Hamann et al. 10. März 2011 13
Recommend
More recommend
