=Paper=
{{Paper
|id=Vol-149/paper-10
|storemode=property
|title=Group Context-aware Service Discovery for Supporting Continuous Service Availability
|pdfUrl=https://ceur-ws.org/Vol-149/paper10.pdf
|volume=Vol-149
|dblpUrl=https://dblp.org/rec/conf/ubipcmm/KangKLL05
}}
==Group Context-aware Service Discovery for Supporting Continuous Service Availability==
https://ceur-ws.org/Vol-149/paper10.pdf
Saehoon Kang, Woohyun Kim, Dongman Lee, and Younghee Lee 62
Group Context-aware Service Discovery for
Supporting Continuous Service Availability
Saehoon Kang, Woohyun Kim, Dongman Lee, and Younghee Lee
them support an alternative service. However, they do not
Abstract—This paper presents our research progress for group consider conflict situation caused by a service being
context-aware service discovery supporting continuous service preoccupied by another user.
availability by providing an alternative service. We believe that To provide an alternative service, service discovery system
service discovery system need to have efficient method for
representing the context of a service and a good algorithm for
need to have an efficient method for representing the context
matching and evaluation. We adopt IOPE model from Semantic of a service, that is, functional semantics, and a good
Web to represent service context and propose perception based algorithm for matching and evaluation for selecting best one.
effect ontology which is useful in ubiquitous home environment. In [4, 5], they represent service context based on the
ontological classification such as Aura’s Supplier or Gaia’s
Index Terms— Service Discovery, Alternative Service, Group Presentation. Gaia evaluates candidates for an alternative
Context, Resource Conflict, Service Ontology service based on the distance in the service ontology hierarchy.
However, it is very hard to build complete ontology to
I. INTRODUCTION
represent service functionality because ontology is built with
The ubiquitous applications being aware of the situation of heuristic criteria, and the discovery results may be different
a user provide user with application services by forming depending on that. Even if it is possible, service developers
service community consisting of various service entities. can not describe service’s full functionality because they does
Service discovery systems discover a service entity, which not consider service’s additional functionalities like alarming
satisfies required constraints, based on the specifications given functionality in TV service not but its main ones.
by ubiquitous applications. Although a lot of researches [1-3, We think the service context is realized in the form of a
8, 9] have tried to enable their service discovery systems to be service action to the user by causing some effects. IOPE
aware of context [10] they have been considered the context (inputs, outputs, preconditions, effects) model proposed by
only in terms of single user. However, their may be various Semantic Web [6] is very popular because it represents
situations where multiple users co-exist in the same service actions systematically. To apply this model to
environment. In those environments, there are different types ubiquitous environments, it is very important how to represent
of contexts from single user environments such as conflict effects for that because the semantics of services are realized
between users, common interest of them. We call these kinds in the form of effects human perceives in many cases such as
of context as group context. Especially, we call the situation light, sound, temperature.
as service availability conflict, where application requests a In this paper, we present our research progress for group
service entity which is not sharable simultaneously and context-aware service discovery supporting continuous
unfortunately already has been preoccupied by another. To service availability by providing an alternative service.
accommodate this conflicting request, service discovery Especially, we focus on the ontology to describe service
should provide an alternative service which satisfies effects and how to evaluate the candidates for best alternative
requirements of the originally requested service if it exists. services.
For example, suppose that an application requests alarm
service and the only alarm service entity in the environment II. PROPOSED APPROACH
which supports only one timer setting for alarming is
preoccupied by another user. In real situation, TVs or audio A. Effect Ontology
services can be used instead of alarm service if they have To build ontology for effect description, we need to
timer setting functionality. By inferring that alarm service analysis a domain to which it is applied. Service effects can be
consists of two functionalities - time setting and making categorized into information providing and state change of the
sound, it is replaced by a TV or audio service which has both world [7]. In ubiquitous home environments, as mentioned
time setting and making sound functionalities. above, the semantics of services are realized in the form of
Although a number of service discovery techniques [1-5] changing state human perceives in many cases because the
have been already proposed in recent years, only few [4, 5] of users of ubiquitous applications continuously interact with
services in the space. For example, the user turn-on a
ubiquitous light in a room, the semantic of the service is the
ubiPCMM 2005 63
brightness level of the room is increased and human perceives Currently, we evaluate service based on both subsumption
its effect by his/her eyes. Therefore, we decide to develop relation and the distance of ontology graph. However, we
effect ontology based on the human perception. At present, we don’t think our method is best. We need to develop more
start from building effect ontology in terms of sight, sound efficient and accurate method.
and temperature. It will be extended gradually. Figure 1
depicts sample effect ontology. III. REMARKS
In this paper, we proposed group context-aware service
Perceptibles discovery to accommodate service availability conflict in
ubiquitous home environments. We have introduced
Sight Sound Temperature perception based ontology to represent service effects. Even
thought it is not sufficient to represent full service effects, we
Brightness Display PlaySound … … … believe that it will be a good starting point for future research.
REFERENCES
… … PlayNoise PlayMusic
[1] Guanling Chen and David Kotz. Context-sensitive resource discovery.
In Proceedings of the First IEEE International Conference on Pervasive
Figure 1. The Effect Ontology Computing and Communications (PerCom 2003), pages 243-252, Fort
Worth, TX, March 2003.
[2] Kouadri Mostefaoui, S., Tafat-Bouzid, A., Hirsbrunner, B., Using
B. Service Description Context Information for Service Discovery and Composition, Proc. Of
the 5th Conf. on information integration and web-based applications and
In IOPE model, service is described with inputs, outputs, services, Jakarta, p. 129-138.
preconditions, effects. In this paper, we does not consider [3] Efstratiou, C., Cheverst, K., Davies, N., Friday, A., An architecture for
preconditions for describing services because how to represent the Effective Support of Adaptive Context-Aware Applications (2001),
Mobile Data Management 2001, p.15-26.
it is beyond of the scope of this paper. Each service action is [4] João Pedro Sousa, and David Garlan, Aura: an Architectural Framework
described by its inputs, outputs, effects. Our service for User Mobility in Ubiquitous Computing Environments, Proceedings
description consists of three parts - attributes-values based of the 3rd Working IEEE/IFIP Conference on Software Architecture
August 25-31, 2002. pp. 29-43.
properties, service states, and IOPE based action. The values [5] Anand Ranganathan, Shiva Chetan and Roy Campbell, Mobile
of service states are dynamically changed at run time and its Polymorphic Applications in Ubiquitous Computing Environments ,
changed state is registered with discovery server periodically. Mobiquitous 2004: First International Conference on Mobile and
Ubiquitous Systems: Networking and Services, Boston, Aug 2004.
Accordingly, the availability of a service is easily known to [6] Semantic Web, W3C, http://www.w3.org/2001/sw/
service discovery. Figure 2 describes SAMSUNG_LCD_TV [7] OWL-S: Semantic Markup for Web Services, W3C,
service. The notation of @ sign means that it describes service http://www.w3.org/Submission/OWL-S/
action. [8] Choonhwa Lee, Sumi Helal, Context Attributes: An Approach to Enable
Context-awareness for Service Discovery, Proceedings of the 2003
Symposium on Applications and the Internet, 2003
; Property [9] M. Keidl, A. Kemper, “Towards context-aware adaptable web services,”
Type := SAMSUNG_LCD_TV; International World Wide Web Conference, pp. 55 - 65 , 2004
Size := 43 inch; [10] Moran, T. P., editor (1994). Special Issue on “Context in Design.”
…
; State information Human-Computer Interaction, Vol. 9, No. 1.
Service_available := true;
OnOffState := True; Saehoon Kang received the BS degree in Computer Science from Korea
Current_channel := 13;
Current_Volume := 20; University, Korea in 1995, and the MS degree in Computer Engineering from
… Information and Communications University (ICU), Korea. He is currently
; Action representation Ph.D. candidate in same university.
@TurnOnTV {
Inputs := {TVSignal}; Woohyun Kim received the BS degree in Computer Science from Soongsil
Outputs : = null; University, Korea in 2000. He is currently in Master Course at Information
Effects : = {PlaySound, BrightnesUp} and Communications University (ICU), Daejeon, Korea.
}
@SetTimeOn { Dongman Lee received the BS degree in Computer Engineering from Seoul
Input : = {Time}; National University, Korea in 1982, and the MS degree and Ph.D. degree in
Output := null;
Effects := {PlaySound, BrightnessUp} Computer Science from KAIST, Korea in 1984 and 1987, respectively. From
} 1988 to 1997, he worked as Technical Contributor at Hewlett-Packard. He is
currently Professor in School of Engineering at Information and
Communications University (ICU), Daejeon, Korea.
Younghee Lee received the B.S. and M.S. degrees in EE from Seoul National
University, Korea in 1976 and 1980 respectively. He received Ph. D degrees
Figure 2. The example of service description in computer science from Universite de Technologie de Compiegne, France in
1984. He is currently Professor in School of Engineering at Information and
Communications University (ICU), Daejeon, Korea.
C. Service Matching and Evaluation
To find best alternative service efficient matching and
evaluation algorithm should be developed. The subsumption
relation is widely used to evaluate goodness of matching.