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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1 2 3 4 5

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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