ENHANCING WEB PROCESS SELF-AWARENESS WITH
CONTEXT-AWARE SERVICE COMPOSITION
Angelo Furno Ph. D. Candidate
University of Sannio
Eugenio Zimeo Ph. D. Tutor
University of Sannio Ph.D. Forum - AWARENESS, SASO 2012 - Lyon 2nd Workshop on Challenges for Achieving
Self-Awareness in Autonomic Systems
University of Sannio, Department of Engineering 82100 Benevento - Italy
Angelo Furno - University of Sannio, Benevento - Italy AWARENESS, SASO 2012 - 2nd Workshop on Challenges for Achieving Self-Awareness in Autonomic Systems
Problem: to take context into account during semantic service design and automatic composition
• context awareness to enhance Web Process self-awareness − essential for implementing self-managing properties of the autonomic computing vision
Pervasive scenario example: TV-Show Episode retrieval and reproduction
Context-aware Semantic Service Design & Composition
Context-aware Service Domain
Problem specification and current context
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Context: “any information that can be used to characterize the situation of an entity. An entity
is a person, place, or object that is considered relevant to the interaction between a user and
an application, including the user and applications themselves.” (Dey and Abowd, 1999)
Angelo Furno - University of Sannio, Benevento - Italy AWARENESS, SASO 2012 - 2nd Workshop on Challenges for Achieving Self-Awareness in Autonomic Systems
Autonomic Workflow (AW)
• executable composition of automatic/manual services
• able to automatically proceed towards the goal
− even if external events change the execution context
• AW life-cycle:
− direct action flow (plan-bind-execute)
− reaction flow (self-awareness)
Context-aware Service Composition
Initial definition of the autonomic workflow (plan)
• Re-planning (parts of) already defined workflow (plan1)
SAWE: Semantic Autonomic Workflow Engine
• Developed at University of Sannio
• Implements the autonomic workflow lifecycle
• OWL + OWL-S
• for Semantic Web Service design
• and problem semantic description
• What about context support?
Autonomic Workflow
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SAWE
AW life-cycle
Angelo Furno - University of Sannio, Benevento - Italy AWARENESS, SASO 2012 - 2nd Workshop on Challenges for Achieving Self-Awareness in Autonomic Systems
Application state
• set of variables and corresponding values the application is able to access or modify.
• Internal state
− set of variables only visible to the application
input, output
referred by pre/post conditions
• External state
− set of variables accessible by:
users
devices
other applications
− the context
Context-aware Web Services
• WS exhibiting dependencies from the context in pre/post-conditions
Context Model
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Angelo Furno - University of Sannio, Benevento - Italy AWARENESS, SASO 2012 - 2nd Workshop on Challenges for Achieving Self-Awareness in Autonomic Systems
Extensible OWL ontology for describing contexts
• semantically model contexts
• context-dependent conditions
Top-level ontology
• context as a set of context dimensions and values
Partial context middle-level ontology:
• domain-independent context dimensions (time, location, etc.)
Designers may specify domain-specific context dimensions and their relationships
OWL-Ctx: (top-level) ontology for context
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OWL-Ctx
top-level
OWL-Ctx
middle-level
Media-Ctx
specification
Angelo Furno - University of Sannio, Benevento - Italy AWARENESS, SASO 2012 - 2nd Workshop on Challenges for Achieving Self-Awareness in Autonomic Systems
Extension of the OWL-S service ontology
• for describing context-aware semantic services
Designers may describe slightly different versions of the same service
• by defining context adaptation rules over a basic OWL-S description
− context condition + context adaptation
− profile, process or grounding properties are adapted when conditions are satisfied
OWL-S Profile, Process and Grounding middle-level ontology
• Contexts or Context dimension values may be used in CTX-Conditions
− a current context reference is used to refer the current situation
may be automatically updated by a monitoring component
OWL-SC (1): Top-level ontology
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OWL-S
OWL-SC
(top level ontology)
Angelo Furno - University of Sannio, Benevento - Italy AWARENESS, SASO 2012 - 2nd Workshop on Challenges for Achieving Self-Awareness in Autonomic Systems
Context adaptations:
• Defaulting an input/output parameter
• Nulling a parameter, not applicable for a specific context condition
• Changing the owls <process:parameterType> of an input/output parameter to a different ontology concept
• Replacing pre-conditions or effects of the basic OWL-S service description
• Changing the WsdlAtomicProcessGrounding input/output section of an atomic Process with a new Wsdl MessageMap
• Changing the WsdlAtomicProcessGrounding section of an atomic Process with a new WSDL operation and/or WSDL portType
Context-dependent conditions:
• Expressed using Semantic Web Rule Language (SWRL)
• Currently supported by our OWL-SC ontology: − current_ctx matches ref_ctx
− current_ctx includes "concept hasValue ontology_individual"
− current_ctx includes "concept.datatype_property = value"
− current_ctx includes "concept.object_property hasValue individual"
OWL-SC (2): Context Conditions and Adaptations
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SWRL context condition (diskSpace: Pervasive scenario)
Angelo Furno - University of Sannio, Benevento - Italy AWARENESS, SASO 2012 - 2nd Workshop on Challenges for Achieving Self-Awareness in Autonomic Systems
Five-Step Composition Process
• manually triggered for initial workflow definition, automatically triggered on monitored events requiring re-planning
1. OWL-SC problem and domain conversion into internal representation
2. Domain and Problem Contextualization (+ serialization)
3. Planning
4. Deserialization and Plan Validation
− Rules & Constraints
5. Contextualized Translation into Standard Language Executable Business Process (WS-BPEL, XPDL, etc.)
Context-aware Composition Tool for Autonomic Workflows
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Angelo Furno - University of Sannio, Benevento - Italy AWARENESS, SASO 2012 - 2nd Workshop on Challenges for Achieving Self-Awareness in Autonomic Systems
Pervasive Scenario: a Context-aware WS-BPEL Composition
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Context-aware Service Domain
Problem specification and current context
WS-BPEL contextualized business process
OWL-S conversion + Contextualization + PDDL planning + WS-BPEL serialization
disk space swrl ctx cond.
Angelo Furno - University of Sannio, Benevento - Italy AWARENESS, SASO 2012 - 2nd Workshop on Challenges for Achieving Self-Awareness in Autonomic Systems
Problems:
• Context may change during planning
• Contextualization not always possible before/after planning
− e.g.: for an abstract service, more than one post-condition may fit the context
− only one of them satisfies the pre-conditions of the next services
e.g. there is disk space for retrieving a HD file but the player is not able to play it
− it is possible that valid composite solutions are indirectly excluded during domain construction
e.g. the HD file retrieval service is selected, but it won’t be possible to reproduce it
Solution:
• Contextualization should be performed during planning
Development of a new planner
• supporting context evaluation at each step of the planning process
• business constraints verification during planning
• support for more complex context conditions and control flow structures
− choice, loops, etc.
Future Work
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Angelo Furno - University of Sannio, Benevento - Italy AWARENESS, SASO 2012 - 2nd Workshop on Challenges for Achieving Self-Awareness in Autonomic Systems
1. L. Bevilacqua, A. Furno, V. di Carlo, and E. Zimeo, “A tool for automatic generation of ws-bpel compositions from owl-s described services,” in Software, Knowledge Information, Industrial Management and Applications (SKIMA), 2011 5th International Conference on, sept. 2011, pp. 1 –8
2. L. Bevilacqua, A. Furno, V. di Carlo, and E. Zimeo, “Automatic generation of concrete compositions in adaptive contexts [to appear],” in Mediterranean Journal of Computers and Networks, oct. 2012
3. A. Furno and E. Zimeo, “Context-Aware Design of Semantic Web Services to Improve the Precision of Compositions [to appear],” in International Conference on Context-Aware Systems and Applications (ICCASA), nov. 2012
4. G. Tretola and E. Zimeo, “Autonomic internet-scale workflows,” in Proceedings of the 3rd International Workshop on Monitoring, Adaptation and Beyond, ser. MONA ’10. New York, NY, USA: ACM, 2010, pp. 48–56. [Online]. Available: http://doi.acm.org/10.1145/1929566.1929573
5. M. Polese, G. Tretola, and E. Zimeo, “Self-adaptive manage-ment of web processes,” in Web Systems Evolution (WSE), 2010 12th IEEE International Symposium on, sept. 2010, pp. 33 –42
Thank You For Your Attention!
References
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