=Paper=
{{Paper
|id=Vol-149/paper-8
|storemode=property
|title=Conflict Management for Media Services by exploiting Service Profile and User Preference
|pdfUrl=https://ceur-ws.org/Vol-149/paper08.pdf
|volume=Vol-149
|dblpUrl=https://dblp.org/rec/conf/ubipcmm/ShinHW05
}}
==Conflict Management for Media Services by exploiting Service Profile and User Preference==
https://ceur-ws.org/Vol-149/paper08.pdf
Choonsung Shin, Daeho Han and Woontack Woo 48
Conflict Management for Media Services by
exploiting Service Profile and User Preference
Choonsung Shin, Daeho Han and Woontack Woo
for playing music by exploiting distributed resources, such as
Abstract— In this paper, we propose Context Manager to display and audio devices in Active Space [5].
resolve conflicts for Context-aware Media services in smart home However, conflicts occur in context-aware media services
environments. Conflicts arise when multiple users access a Media when more than one user reaches the Media service
service or when various Media services share limited resources to simultaneously due to sharing of the space and service. Hughes
provide customized responses. In order to resolve conflicts among
pointed out that conflicts arise when residents share the
users, the Context Manager sums up preferences of users who
collide with each other and recommends specific contents ordered
appliances, such as radio, television, and etc. [7]. W.Keith
by the summed preference. It also resolves conflicts among Media classified the conflict problem among users as a challenge in
services by selecting a Media service with the highest preference. ubiquitous computing home environments [8]. Besides,
Furthermore, Context Manager resolves conflicts among Media conflicts also arise when more then one Media service shares
services occupied by users with the Media service the limited resources within their environment. Ajay A
recommendation. During experiments on ubiHome, a smart home considered this kind of conflicts as conflicting reactions in
test-bed, the proposed method resolved conflicts among users and behavioral system [13]. Conflicts also arise when more than
Media services while giving higher satisfaction to users than a one user access different Media services. Meyer defined the
resolution method selecting a specific user. Therefore, we expect ubiquitous computing environment as multi-user and multi
the proposed management method can play a vital role in
device environments [9]. Furthermore, S.M. Easterbrook
Context-aware Media services for offering personalized services
to users by resolving service conflicts among Media services as pointed out the complexity of home environments like “the less
well as users. cohesive the group, the more conflicts” [11]. Consequently, in
order to develop Context-aware Media services for home
Index Terms—Context-awareness, Service Conflicts, Service environments, it is necessary to resolve conflicts not only
Profile, Media Service, User Preference among Media services and among users, but also among Media
services provided to different users.
I. INTRODUCTION Meanwhile, most research, aimed on resolving conflicts, has
been done on smart home and intelligent office. MusicFX
T HE aim of ubiquitous computing is to provide users with
intelligent services based on the information obtained from
distributed and invisible computing resources [1]. Users exploit
supports group music selection in a fitness center by exploiting
users’ preferences on each music station [12]. Reactive
these services without any cumbersome interface or learning Behavioral System (ReBa) resolves conflicts among devices in
procedures. Therefore, context-aware applications are office environments by applying layering architecture of
considered to be important applications in the ubiquitous activity bundles consisting of users’ activities and reactions of
computing environments that offer appropriate services to environments [14]. Reconfigurable Context-Sensitive
users by utilizing contextual information of users and their Middleware for Pervasive Computing (RCSM), an object-
surroundings [2][3]. Especially, context-aware Media services based framework, ensures independence between sensors and
are one of the emerging applications for smart home application services, forms ad-hoc communication between
environments. The Home Media Space (HMS) allows users to them, and delivers the necessary context to the applications
teleconference with remote users through video streaming [4]. [16]. Context Toolkit collects, interprets, and delivers context
Context-based Media Player (cMP) offers various movie between sensors and application services [15]. Contextual
contents by utilizing user’s contextual information and Information Service (CIS) manages contextual information
preference [6]. Music Player Application provides functions such as location and characteristics of users, devices, and status
of network to provide contexts to application services [17].
Nevertheless, context management techniques in the
previous research have various limitations when they are
Manuscript created June 17, 2005. This work was supported by Samsung applied to multi-user environments with various applications.
Electronics Co., Ltd. in S.Korea MusicFX only utilizes users’ preferences on all situations of
Choonsung Shin is with Gwangju Institute of Science and Technology,
Gwangju, 500-712, S.Korea (e-mail: cshin@gist.ac.kr ) users and lacks consideration of multiple services [12]. In case
Deaho Han is with Samsung Electronics Co., Ltd, Seoul, 135-284, S.Korea of ReBa, it is difficult to provide particular services to each user
(e-mail: bighoya.han@samsung.com ) because ReBa focuses on the service for grouped users by
Woontack Woo is with Gwangju Institute of Science and Technology, inferring main activities from the environment [14]. In the
Gwanju, 500-712, S.Korea (Corresponding author to provide phone:
82-62-970-2226, fax: 82-62-970-2249, email: wwoo@gist.ac.kr ) RCSM, context management does not consider shared devices
ubiPCMM 2005 49
or services because contextual information services are other services. In addition, the unified-context ensures reducing
provided only through individual device possessed by each additional management required to translate the context into
user [16]. In the case of Context toolkit and CIS, application other forms according to individual services. Unified context
developers have to consider both conflicts among services and employs the different types of contexts according to the role of
among users since contexts are delivered to applications when each context. These include Preliminary Context, Integrated
current context of environment matches an application- Context, User Conditional Context, Service Conditional
specified condition [15][17]. Context, and Final Context.
In order to resolve the above-mentioned limitations and
conflict problems, we propose Context Manager. It consists of Preliminary Context (PC): A unified context which
four components: Context Preprocessor, Service Profile describes current situation of a user and his environment,
Manager, Final Context Deliverer, and Conflict Manager. and includes all or part of 5W1H.
Context Preprocessor matches and filters contexts coming from Integrated Context (IC): A unified context which
users and services and provides them to Service Profile describes current situation of a user and his environment,
Manager. Service Profile Manager maintains static and and includes all of the 5W1H.
dynamic information of a registered Media service. With Conditional Context (CC): A unified context which
Profile Manager and Context Preprocessor, Conflict Manager expresses an action and parameters of a service and related
detects and resolves the conflicts in context-aware Media user condition.
services. Final Context Deliverer then sends the conflict-free Final Context (FC): A unified context which describes a
context to the registered service and other Media services. user, his environments, and service action and parameters. It
Therefore, the proposed Context Manager resolves the is used for triggering a service.
conflicts among users by recommending specific contents
sorted by the preferences of conflicting users. It also detects ubi-UCAM 2.0 (Unified Context-aware Application Model
conflicts among Media services by utilizing their service for ubiquitous computing environment) is context-based
profile and resolves by selecting a Media service with the application model to provide users with the personalized
highest preference. Furthermore, it resolves conflicts among service by exploiting context in ubiquitous computing
Media services involved with different users by recommending environments where various kinds of sensors and services are
the services sorted by the preference of the conflicting users. distributed [20]. Ubi-UCAM 2.0 is composed of ubiSensors
Through implementation and experiment, we found that the and ubiServices. The ubiSensors and ubiServices exchange
proposed Context Manager has the following advantages. First, contextual information with several types of contexts based on
the recommendation of services and contents gives users higher the unified context. Figure 1 shows the overall architecture of
satisfaction than the resolution method that selects a user or the ubi-UCAM 2.0.
service when service conflicts arise. In addition, with
recommendation, users become aware of others’ needs as well ubiService FC: Final Context
PC: Preliminary Context
as preferences. Therefore, the proposed resolution method can Service Provider IC: Integrated Context
play an important role to congregate family members while SCC/SS FC
SCC: Service Conditional context
resolving conflicts among them and Media services. FC’ SC: Service Status
In te rp re te r
UCC’
Context Manager UCC: User Conditional context
This paper is structured as follows. In Chapter 2, we
FC/IC
introduce context-aware application model for ubiquitous ubiService
Context Integrator
computing environments and context-aware Media services. UCC FC/PC
Chapter 3 describes the architecture of Context Manager and Self Configuration Manager
the conflict resolution method. Chapter 4 describes how the
PC/FC FC PC/FC FC
Context Manager manipulates service profile information. Network
Experimental setup and results are discussed in Chapter 5. PC PC
Finally, we conclude in Chapter 6.
Self Configuration Manager
ubiSensor
Preliminary Context Generator
Signal processing
II. CONTEXT-AWARE MEDIA SERVICE A sensor
A. Context-aware Application Model
Fig. 1. Architecture of ubi-UCAM 2.0
In order to provide the personalized service, we utilize unified
context and ubi-UCAM 2.0. The unified context represent a
As shown in Figure 1, ubi-UCAM 2.0 consists of ubiSensors
user’s context information as 5W1H (Who, What, Where,
and ubiService. A ubiSensor is composed of a physical sensor,
When, How, and Why) [19]. 5W1H contains comprehensive
Signal Processing module, Preliminary Context Generation
information about user and his surrounding environment. With
module and Self Configuration Manager. The physical sensor
each field having sub-fields, the unified context also represents
perceives a change related to a user and his environment. Signal
detailed information about the user. The unified context
processing module extracts feature information from the sensed
expressed with 5W1H ensures the independence between
signal. Preliminary Context Generation module generates a
sensors and services. It also has the advantage to be re-used by
preliminary context from the feature information. The
Choonsung Shin, Daeho Han and Woontack Woo 50
ubiSensor delivers the context to ubiServices located within a sensors, ubiTrack. The ubiCouch sensors are couch sensors
working area through a multicast group established by Self comprised of on/off switches and PIC16F84, to detect user's
Configuration Manager. A ubiService is composed of Context behaviors. ubiTrack is infrared-based location tracking system
Integrator, Context Manager, Interpreter and Service Provider. that tracks user's location [21]. Furthermore, in order to control
Context Integrator collects preliminary contexts created by these services, users utilize ubiRemocons, a remote controller,
various ubiSensors located within a working area during a implemented with Personal Java [29].
given time interval. It classifies the preliminary contexts to Based on the Media services and sensors, ubiTV application
each sub-element and analyzes the sub-elements by applying a provides residents with the Media services according to users
decision making technique. Context Integrator generates and their environments.
integrated contexts of each user and delivers them to Context
Manager. Context Manager searches conditional context from a C. Service Conflicts in Context-aware Media Services
Hash-table, which manages specific service action and Unlike single user and single service environment, applications
condition, corresponding to each integrated context. It in the ubiquitous computing environment have to respond to
generates a final context to be used by applications after users while considering other services and applications, along
resolving conflicts among users and services. Finally, Service with various users within a services area. In case of ubiTV, it
Provider executes an appropriate action with the parameters provides users with various Media service by exploiting users’
described in the final context. contextual information within a service area. In order to
B. Context-aware Media Services provide services, the ubiTV application requires one or more
resources, such as display device, sound device, or both,
ubiTV is a set of context-aware application that provides users
according to their properties. Furthermore, in such service
with various Media services in smart home environments [20]. environments, the number of users accessing the same Media
ubiTV is based on ubi-UCAM 2.0 and offers various media service is not limited. Therefore, the Media services all the time
services, such as television, music, movie, and Internet service, cannot provide users with their personalized responses
according to users’ contextual information. Figure 2 shows the We define such situation as a service conflict [13]. In the
overall architecture of ubiTV application. case of ubiTV, we classify service conflicts into three types
according to sources of conflicts: service conflicts among
-TV Service -Movie service -Music service -Internet service multiple users, service conflicts among multiple Media services
TV application Media player MP3 player IExplorers and service conflicts among multiple users and multiple Media
ubiService ubiService ubiService ubiService services. Service conflicts among users are caused by use of a
Service Provider Service Provider Service Provider Service Provider
SCC/SS FC SCC/SS FC SCC/SS FC SCC/SS FC
Media service by multiple users. In this situation, involving
Interprete
Interprete
Context Manager Context Manager Context Manager Context Manager
Interprete
Interprete
FC’ FC’ FC’ FC’
UC
C’
UC
C’
UC
C’
UC
C’ several users, the Media service has to choose one user who
r
r
r
r
FC/IC FC/IC FC/IC FC/IC
Context Integrator Context Integrator Context Integrator Context Integrator
U
CC FC/PC
U
CC FC/PC
U
CC FC/PC
U
CC FC/PC
will be offered with the customized service. Figure 3 illustrates
Self Configuration Manager Self Configuration Manager Self Configuration Manager Self Configuration Manager
a service conflicts scenario among users
ubiSensors Location/ Orientation /ID
Body gesture Service control
News Drama
TV
ubiCouch User Context Manager
ubiTrack
Fig. 2. The architecture of ubiTV
Fig. 3. A service conflict among users
As shown in Figure 2, the ubiTV application is composed of
Media services, a kind of ubiService, and various sensors, a As shown in Figure 3, a service conflict arises when users A
kind of ubiSensor. Television service consists of Samsung PVR and B are trying to watch their preferred broadcasts from
TM
application and ubiService. It provides users with various television service. Therefore, television service has to choose
one user. Next, service conflicts are caused by providing
programs through 4 broadcasting channels in Korea: Korea
services among multiple Media services. Due to the conflict,
Broadcasting System (KBS), Seoul Broadcasting System
the Media service cannot provide users with customized
(SBS), Munhwa Broadcasting Corporation (MBC), and
responses. Figure 4 shows a conflict among Media services.
Educational Broadcasting System (EBS). Movie service is
composed of Media Player TM and ubiService. It provides four
TV
genres of movies, such as, Sci-Fi, Korean, Animation, etc.
Music service consists of MP3 player and ubiService. It offers
Music
several genres of music stored in the computer. Lastly, Internet
service, comprised of Internet Explorer TM and ubiService,
offers useful web pages such as weather, stock, and game. Fig. 4. A service conflict among Media services
These services are deployed on the same computer having a
large display and a surround speaker in the smart home test-bed. As can be seen in Figure 4, television application and music
In addition, ubiTV also exploits various sensors: ubiCouch application start to provide their customized services
ubiPCMM 2005 51
simultaneously. Therefore, their sound interferes with each Fig. 6. The architecture of Context Manager
other. Service conflicts among users and applications are As can be seen in Figure 6, first of all, Context Manager
caused by the use of multiple services by multiple users. This receives three types of contexts, user context, a kind of FC,
kind of conflict scenario is similar to the conflict among service contexts, a kind of FC, and User Conditional Context, a
multiple Media service, but different users are assigned to each kind of CC. It then resolves conflicts among users with the user
Media service. Figure 5 shows a service conflict scenario contexts. After resolving conflicts among users, Context
among users and Media services. Manager builds final context based on the conflict-free context.
At that time, it tries to resolve conflicts among Media services.
In case of single user, it selects a media service with the highest
TV
preference among users’ Media services. Context Manager
then sends the selected Media service to Context Buffer. In case
of multiple users, it selects a Media service of each user’s
Music
Media service .Conflict Manager then resolves conflicts among
users and Media services by making a final context which
Fig. 5. A service conflict among users and Media services implies service recommendation. Finally, Context Manager
delivers the final context to Service Provider and other Media
As shown in Figure 5, a service conflict arises when user A is services within the same service area.
trying to use a television application while user B is trying to
use a music application. Therefore, both television and Music A. Conflict Resolution among Multiple Users
can not provide customized responses to each user. Conflict Manager resolves conflicts caused by users trying to
To deal with these conflicts, resolution methods have to use services within the same service area. To resolve the
resolve the conflict according to sources of conflicts. conflict, Conflict Manager manipulates user contexts in two
Furthermore, in order to reflect the change of users’ steps: building a user conflict list and recommending preferred
preferences and their environment, the conflict resolution contents from the list. Figure 7 illustrates the resolution
methods must adapt to users and their environment. In this procedure on service conflicts among users.
paper, we deal with these three kinds of conflicts: among users,
among Media services, and among Media services given to Users’ changed contexts Users’ previous contexts
different users. User 1 User 1
User 2 5W1H 5W1H User 2
User n User m
Service
III. CONFLICT MANAGEMENT Building User 1 status
5W1H User 2
a conflict list User k
In ubiTV application, Context Manager is located in each
Conflicting users
Media service and provides Final Context to the registered
service. In order to provide Final context, Context Manager Assigning User 1 Service
User 2
User Preference 5W1H User k Profile Manager
manages conflicts in its point of view. In case of conflicts
among users, the Context Manager resolves them by User’s preferences
recommending contents of conflicting users. It also plays a role
Building User 1
in resolving conflicts among Media services by utilizing Final a Final Context Preferences User 2
User k
Contexts obtained from the Media services and service profile
of a registered service. Furthermore, in order to resolve
A Final Context 5W1H
conflicts among Media services given to different users,
Context Manager groups the conflicting services by each user
and then recommends the services to users. Figure 6 shows the Fig. 7. Conflict Resolution among Users
overall architecture of Context Manager.
As can be seen in Figure 7, first of all, Conflict Manager
Conditional Contexts
Service
makes a conflict list of matched user context on users who are
5W1H Final Context Provider expected to cause conflict among users, including those who
5W1H
5W1H Service Profile Manager
Deliverer
Users are currently using the services. In this procedure, users who
CC FC
Integrated Contexts
Conflict Manager leave the service area are excluded from the list because we
5W1H assume they do not want to enjoy the service any longer. It then
5W1H 5W1H User Conflict
5W1H
5W1H Matching Context Buffer
Resolution assigns preferences obtained from Service Profile Manager to
Users
Final Contexts
5W1H 5W1H 5W1H each user’s context. Consequently, Conflict Manager builds
5W1H Filtering 5W1H Service Conflict Service & User Final Context’ each User Preference (UPij) represented by Equation (1), where
5W1H
5W1H Resolution 5W1Hs Conflict Resolution -Service state
-Service notify j is each preference of contents, i is each user, and k is the
number of contents of the registered service.
Media
Services User i’s preferences = {UPi1, UPi2, •••, UPik } (1)
Choonsung Shin, Daeho Han and Woontack Woo 52
Conflict Manager then builds a Final Context having Sitcom, respectively. Summarizing the preferences, Conflict
preferred contents ordered by users’ preferences. In this Manager obtains the preference of 0.5, 0.9 and 0.6 on the
process, conflicts are handled in several ways according to the contents of the service. Consequently, Conflict Manager
number of users within the service area. In the case of one user, obtains a content list containing Drama, Sitcom and News
we know that there is no conflict among users. Therefore, programs ordered by the preference value.
Conflict Manager just selects the user context as a result of B. Conflict Resolution among Multiple Media Services
conflict resolution. However, we have to consider the situation
Conflict Manager also detects and resolves conflicts caused
when there is more than one user within a service area. In this by multiple Media services that share limited resource in a
situation, Conflict Manager sums up each user’s preference on service area. In order to detect possible conflicts among media
contents. In order to obtain the summed preference, we utilize services, Conflict Manager manipulate contexts in two steps:
McCarthy’s Group Preference (GPj) algorithm defined by building a conflicting service list and building Final Contexts.
Equation (2), where N is the number of users, i is each user, and Figure 9 shows a conflict resolution procedure on service
j is the number of contents [12]. conflicts among Media services.
N
Services’ changed contexts
GP j = ∑ UPij (2)
Svc 1
i=0 Svc 2
Svc n 5W1H
Conflict Manager then builds a final context with the
Building Svc 1
summed preferences GPj. Finally, Conflict Manager delivers a service list 5W1H Svc 2
Svc m
the Final Context to Context Buffer. In case of user selection,
Conflicting services
Conflict Manager also offers the final context to service
conflict resolution module. Figure 8 shows a service conflict User 1 User
Collecting Svc 1 User 2
scenario among multiple users. Preference Conflict Resolution
resources User k
resources Svc 2
Recommendation
Available contents Drama Resolved-context
Sitcom 5W1H User 1
Television -News News Selected
5W1H
A Final Context 5W1H User 2 5W1H
Final Contexts
-Drama 5W1H Selection & User n
Service User 3 New context contexts
Recommendation
-Sitcom
5W1H 5W1H 5W1H Explicit context only
5W1H 5W1H 5W1H 5W1H 5W1H Fig. 9. Conflict Resolution among Services
Sitcom 5W1H Explicit & Implicit
Drama context Selection
Previous context
As shown in Figure 9, Conflict Manager collects FCs of
(news:0.2, (news:0.3, User 1 5W1H
5W1H
other services and monitors resource usage of other services
drama:0.3, drama:0.6, User 2 5W1H Weighted
sitcom:0.5) sitcom:0.1) Recommendation
Implicit context only
within the same service area. Conflict Manger then builds a FC
User 1 User 2 by exploiting the collected services and a FC of the registered
Media service. Figure 10 shows a conflict scenario among
Fig. 8. A conflict scenario among multiple users
Media services and a resolution procedure on the scenario.
As shown in Figure 8, there is a television service providing
Media services Conflict resolution (Music service)
user 1 with a sitcom program in a service area. Simultaneously, Preference:0.8
user 2 is trying to use the same service and user 3 is leaving Television Movie Service Selected
Service Shared Resources Service context contexts Single user
from service area. Therefore, a service conflict arises due to use -sound Music 5W1H
Preference 0.2 5W1H 5W1H Television
of the same television services by two users. In this conflict -display
Television 5W1H 5W1H
situation, Conflict Manager builds a conflict list consisting of Music Movie 5W1H 5W1H
Multi user
contexts of user 1 and user 2, depicted in Table 3. Service Preference: 0.5
User1 5W1H Television
User2 5W1H Movie
Table 3. A conflicting user list
User 1
Who What
User 1, Preferences = {News: 0.2,
FC 1 Television, News Fig. 10. A conflict scenario among Media Services
Drama:0.3, Sitcom, 0.5}
User 2, Preferences = {News: 0.3, Television, Drama
FC 2 In the service scenario, Music service, Television, and
Drama:0.6, Sitcom, 0.1}
Movie service share a sound resource of Television.
Based on the group preference algorithm, Conflict Manager Furthermore, Television and Movie services need a display
sums every preference of each user based on the conflicting list. resource to show their visual contents. Music service is
In the scenario, user 1 has the ordered preference on contents of providing user 1 with Music service. At that time, Television
television service: 0.2, 0.3, and 0.5 to News, Drama, and and Movie services are about to start. Therefore, due to the
Sitcom, respectively. User 2 has the ordered preference on sharing of a sound resource, Television and Movie service
contents of television: 0.3, 0.6, and 0.1 to News, Drama, and cause a conflict with Music service. Conflict Manager of
ubiPCMM 2005 53
Television and Movie services send a FC containing their status Media services Conflict resolution (Music service)
Resolved-context
to Music service. Music service than receives those FCs and Television
Preference:1.2 Movie 5W1H
5W1H
Selected
builds a conflict service list. The list also includes a user’s Service Shared Resources Service contexts
5W1H Selection &
Recommendation
context coming from user conflict resolution module. Table 4 -sound Preference: 0.5
User2 5W1H 5W1H Explicit context only
-display User1 5W1H 5W1H 5W1H 5W1H
shows the conflicting service list. Television Previous Explicit & Implicit
Music Movie context context Selection
Service Preference:0.7
Table 4. A conflicting service list Television 5W1H 5W1H
Movie 5W1H Weighted
Recommendation
Who What Television Implicit context only
Music, On, Resources ={sound}, User 1 User 2
Music User 1
Preference = 0.5
Television, On, Resources = {sound, Fig. 12. A service conflict among users and Media services
FC 1 User 1
display}, Preference = 0.8
Movie, On, Resources = {sound, display}, As can be seen in Figure 12, the scenario is similar to the
FC 2 User 1
Preference = 0.2
conflict scenario in multiple Media services. However, the
users involved in each service are different. Music service has
As can be seen in Table 4, Conflict Manager of Music been occupied by User 2 and Television service is about to be
service recognizes the sound conflict with Television and engaged by User 1. Therefore, Conflict Manager of Music
Movie service. It then gathers conflicting resources which are service builds a conflicting list containing Music, Movie and
occupied by other Media services with higher preference than Television services, depicted in Table 5.
its registered service. According to the preference, Conflict
Manager includes resources of the Television service, but Table 5. A conflicting service list
excludes resources of Movie service. Finally, it delivers the
resource list containing a sound element as a resolution result to Who What
Context Buffer. Music, On,
Music User 2
Resources = {sound}, Preference = 0.7
C. Conflict Resolution among Users and Media services Television, On,
Lastly, Conflict Manager resolves service conflicts caused FC 1 User 1 Resources = { sound, display},
Preference = 1.2
by multiple Media services occupied by different users. In
Movie, On,
order to resolve expected service conflicts, it utilizes user’s FC 2 User 1 Resources = {sound, display},
services list coming from service conflict resolution module. Preference = 0.5
Figure 11 shows the resolution procedure on service conflicts
among Media services and users Conflict Manager then classifies the services to each user
group according to the user of each service. Based on the list, it
Svc 1
User’s service list 5W1H Svc 2 selects each representative service from user’s services.
Svc n
Therefore, Music service and Television services are assigned
Conflicting services
to user 2 and User 1 respectively. Table 6 shows the selected
services.
User k
Building {Svc1, Preference, Resources} User 2
User 1 Table 6. A representative service list
A Final Context {Svc2, Preference, Resources}
Who What
Music, On, Resources ={sound},
FC 1 User 2
Preference =0.7
A Final Context 5W1H
Television, On, Resources = { sound, display},
FC 2 User 1
Preference = 1.2
Fig. 11. Conflict Resolution among Media services and Users
Finally, Conflict Manager builds a Final Context consisting
As shown in Figure 11, Conflict Manager builds a of conflicting services based on the service list. In this case, the
conflicting service list from FCs. It then gathers the conflict list is comprised of Music and Television services ordered by
service name to be used for the recommendation ordered by users’ preference. Therefore, Conflict Manager obtains a Final
service’s preference. Conflict Manager then builds a Context having Music service and Television services.
recommend service list by gathering names of services. Figure
12 shows a service conflict scenario among Media service
given to different users and a resolution procedure on the IV. SERVICE PROFILE MANAGEMENT
scenario.
As mentioned before, Context Manager has a role in resolving
conflicts related to a registered Media service. Therefore, it
requires static and dynamic information of the service. Service
Profile Manager has a role in managing the profile information.
Choonsung Shin, Daeho Han and Woontack Woo 54
The next session explains how Service Profile Manager As can be seen in Figure 13, SPM requests properties of the
maintains the service profile information. registered service from Service Provider when an application
starts serving users. The requested information is the Service
A. Service Profile Information of the registered service. SPM also receives SCC
Service Profile is the information which is used to resolve from the Service Provider. Furthermore, SPM collects UCCs
service conflicts. It combines wide range of information about from UPMs of wearServices of users’ personal stations such as
the service: Service Information, Conditional Contexts, Service PDA while serving users. SPM manages the UCCs with
Status, etc. Hash-table and provides them with Context Matcher to match
1) Service Information ICs. SPM also offers Service Status information to Conflict
Service Information is unique information used for Manager and receives a Final Context from it after resolving
identification within a service area. It consists of Service Name, service conflicts. Finally, SPM provides Service Information
Resources, and a Service Area. Service Name is a unique name and Service Status to Final Context Deliverer
and used to identify it within a service area. The service name
enables Context Manager to identify each Media service within
a service area. Resources are the devices needed for Media V. EXPERIMENT
service to provide services. A Service Area is a location of the We first surveyed on how often family members conflict with
registered service. It also implies the area of service conflicts each other in daily activities. We then evaluated the
among applications effectiveness of the conflict resolution method based on the
2) Conditional Contexts ubiTV. The proposed conflict resolution method recommends
Conditional Conditions are conditions of an application to several contents or services sorted by conflicting users’
provide users with customized services. They are divided into preferences when multiple users attempt to access a registered
two types of conditions: User Conditional Contexts (UCC) and service. In addition, it selects one Media service when more
Service Conditional Contexts (SCC). The UCCs are obtained than one Media service is simultaneously involved to the same
from User Profile Manager (UPM), a kind of wearService resource. Finally, we conducted a survey on the usefulness of
[27][28]. On the other hand, SCCs come from Service Provider the conflict resolution method to family members.
and are configured by application developers.
3) Service Status: A. Implementation
Service Status describes currents status of the registered Media In order to implement the proposed Conflict Manager, we
service including user’s context and is represented with 5W1H. utilized ubi-UCAM 2.0. The ubi-UCAM 2.0 is a unified
“Who” is a user who currently uses the Media service. “What” context-aware application model for ubiquitous computing
is a current state of the Media service. The Media service can be environments supporting independence between sensors and
stayed on a state among service states: On, Off, Waiting, Pause applications [19]. Especially, the proposed Context Manager
and Recommending. These states are used to recognize service was implemented as a Context Manager of ubiService in the
conflictions. “When” maintains time information when the user ubi-UCAM 2.0. The ubi-UCAM 2.0 also utilize unified context
started to use the registered service. “Where” is a user’s to represent and share users’ contextual information among
location within a service area. “How” is user’s current state. various applications. The unified context represents the
“Why” is the reason why a current user wants to spend his time contextual information as 5W1H (Who, What, When, Where,
on the service. How and Why). We then applied the ubiService recommending
B. Service Profile Manager contents and services to each Media service of ubiTV
application such as television, movie, music, and Internet
In order to manage the profile information of the registered service, in ubiHome test-bed [26]. Figure 14 shows an example
service, Service Profile Manager (SPM) obtains service of service recommendation.
information from Service Provider and UPM, and provides the
information to Conflict Manager and Context Deliverer. Figure Recommendation
13 shows the overall architecture of SPM
Conditional Context
UPM Default Service Provider
User 1
---
User N
Context Matcher Service Information
Final Context
Name ID
Deliverer
Service Status
Conflict Manager (a)TV screen (b) User’s PDA
5W1H 5W1H
Fig. 14. Service recommendation
Fig. 13. The architecture of Service Profile Manager
In this scenario, there are two users in ubiHome. They are in
conflicts due to their preference on the television. User 2 wants
ubiPCMM 2005 55
to enjoy News program, but user 1 is already enjoying Drama. B. Experimental Results and Analysis
Therefore, the Television service recommends available In order to measure the usefulness of the resolution method of
contents sorted by their preferences. Finally, the Television the proposed Context Manager, we experimented on user
service recommends News, Drama, and Education programs on conflict in such setting. To test the method, we employed a
User 2’s PDA and the large screen. After their discussion about television service that users spend most of their time on
television programs with recommended contents, they decide watching in their home. While using the television service,
their proper program in this conflict situation. family members cause conflicts due to their preferences and its
Furthermore, to set up the service condition of each Media broadcasts. In our experiment, the television service
service, we conducted a survey on service preferences of users recommends preferred genres of conflicting users in that
about their home environment. The survey was conducted for conflict situation. The service then gathered feedback of users
the home appliances frequently used in living room. Seventy in pre-defined amount of time and judged the hit on the
persons, (40 parents / 30 children), were asked the following recommendation. We did this experiment from 18:00 to 24:00
questions. in two weeks and obtained 185 conflicting samples from three
users. Finally, we have built a hit matrix to know how well it
Question 1: What kind of services or appliances do you use worked. Table 10 shows hit ratio on the recommended genres
frequently in your home? of each users.
Question 2: When do you usually use the services answered in
the Question 1? Table 10. Hit ratio on recommended genres (unit :%)
Users Hits News Drama Edu. Ani. Etc
As a result, we found that parents usually spend their time on Father 38 34 10 10 5 41
watching television around 9 P.M. Especially, they prefer to Mother 41 17 27 43 4 9
watch news to get social or weather information through the Son 44 12 21 17 22 28
television. However, children usually spend their time by
watching movie or using Internet. They also enjoy watching As shown in Table 10, the users show different
sitcom or comic programs through television. Based on their characteristics on the recommendation. Father expressed
preference and time, we assigned conditional contexts for each higher selection on News program than that of other programs,
user to services of ubiTV. Furthermore, for the experiment, the but showed relatively low hit ratio than other users. In case of
number of family members was three: two parents, and a son. mother, most of the hits are related to Drama program. Son
This is the average family size in Korean family system aged selected various programs compared with father and mother.
from 30 to 40 [30]. He also shows relatively higher hit ratio than others. However,
In addition, in order to decide amount of conflict in home they were unlikely to choose their preferred program soon after
environment, we questioned 70 volunteers in ages from 10 to content recommendation. This is because Context Manager
60 who had experienced context-aware service supporting enabled them to spend their time on talking about the current
conflict resolution. They were asked to answer the following program with recommended programs. They then decided a
question. suitable program to accommodate those users. Especially,
mother encourages her son to watch educational programs
Question 3: Who is the most related person when you are trying when they were together.
to use television service? In addition, in order to verify usefulness of
recommendation of services, we configured properties of each
Table 9 shows the amount of conflict among family members Media service. In our experimental setting, all the Media
based the survey. services were on the same computer having a large screen and a
Table 9. The amount of conflict among family members (Unit: %) sound device. Table 11 shows the properties given to each
Media service.
Father Mother Children
Father - 40 60
Mother 30 - 70 Table 11. Property of Media services
Children 33 20 47
Services Resources
Television {sound, display}
As shown in Table 9, the conflicts appeared high in the
viewpoint of parents when they were using the service with Music (sound)
their children. In the case of children, they showed high conflict Internet {display}
rate when they spend their time on using the service with Movie {sound, display}
siblings. This result implies that conflicts are occurred because
the preferences of each family member are different in using As can be seen Table 11, each Media service has its own set
services in home environment. Moreover, each member feels of required resources, such as sound, display, or both,
service conflicts differently. This is because the persons who according to the resources it uses. Therefore, services which
are together are different with each other, when they spent their require the same resource cannot be executed simultaneously.
time on using the services in the living room. Such service can start after stopping other services. For
example, the television service uses sound, and display
Choonsung Shin, Daeho Han and Woontack Woo 56
resources and Internet service needs display resources. In this VI. CONCLUSION
situation, those two services cannot be executed at the same In this paper, we proposed the Context Manager to resolve
time, because they share the display resource. In order to service conflicts that arise when multiple users access a media
observe hit ratio on service recommendation, we monitored the services and when the media services are trying to share
Media services in ubiHome. Table 12 shows the hit ratio on resources in the smart home environment. In order to resolve
recommendation of service conflicts among Media services service conflicts among users, the proposed Context Manager
given to different users. recommended available contents ordered by preferences of
Table 12. Hit ratio on recommended services (unit :%) conflicting users. The proposed Context Manager also detected
conflicts among Media services by utilizing their service
Users Hits TV Music Movie Internet profile, and resolved them by selecting a Media service having
Father 21 38 34 9 19
the highest preference. Furthermore, the Context Manager
Mother 43 40 31 17 12
resolved the conflicts among Media services occupied by
Son 55 30 16 25 29
different users by recommending conflicting Media services.
Through the experiment on ubiTV application, we have shown
As shown in Table 12, the users showed their characteristics the effectiveness of the proposed resolution method.
on each service recommendation. Father shows relatively low However, several problems are still remained. The
hit ratio than that of other users. It means that he usually proposed recommendation method needs more improvements
consents on a current service of other users. However, mother to resolve conflicts, even though it gives users higher
and son selected another service rather than enjoying a current satisfaction than selection method. In some situation, the
service. In case of mother, the selections were made for the recommendation is unnecessary or has to give users more
family. On the other hand, son’s selections were made for information. In addition, we have to observe the conflicts and
himself. Nevertheless, we found that even though they changed resolution results because preferences of users are changing in
the current service, they didn’t choose their preferred program time to time. Furthermore, we have to elaborate more on the
soon after the recommendation. They spent their time to talk usage of resources to accommodate various appliances and
about the current service and recommended services and then devices in home environments.
decided a suitable Media service.
Finally, in order to evaluate the satisfaction of the proposed ACKNOWLEDGMENT
conflict resolution method, we questioned following question
to 30 volunteers in ages from 20 to 39 who had experienced The authors would like to thank Seiie Jang for his valuable
ubiTV application supporting recommendation. We then input and useful discussion about conflicts in context-aware
compared the result with that of a resolution method selecting a applications.
user’s context [25].
REFERENCES
Question 1: What do you think of context-aware services that [1] Mark Weiser. Computer of the 21st Century. Scientific American, 265(3):
recommend users’ conflicting services and contents when 94-104, September, 1991.
[2] Schilit, B., Adams, N. Want, R. Context-Aware Computing. Proceeding
several members try to use them at the same time? of the 1st International Workshop on Mobile Computing System and
Applications, pp. 85-90, 1994.
Table 13 shows the user satisfaction on the proposed [3] Anind K. Dey, “Understanding and Using Context. Personal and
resolution and the resolution method selecting one user. Ubiquitous Computing, Special issue on Situated Interaction and
Ubiquitous Computing, 5(1), 2001.
[4] Neustaedter, C. and Greenberg, S. “The Design of a Context-Aware
Table 13. User satisfaction (%) Home Media Space”, Proceedings of UBICOMP 2003 Fifth International
Conference on Ubiquitous Computing. 297-314, LNCS Vol 2864,
Age User selection Service recommendation Springer-Verlag.
20~29 59 73 [5] Manuel Román, Christopher K. Hess, Renato Cerqueira, Anand
30~39 53 71 Ranganathan, Roy H. Campbell, and Klara Nahrstedt, "Gaia: A
Middleware Infrastructure to Enable Active Spaces.", In IEEE Pervasive
Computing, pp. 74-83, Oct-Dec 2002.
As shown in Table 13, the respondents showed higher [6] Y.Oh, W.Woo, "A unified Application Service Model for ubiHome by
satisfaction on the proposed resolution method than that of Exploiting Intelligent Context-Awareness," Proc. Of Second Intern. Symp.
resolution method selecting a user with the highest preference. On Ubiquitous Computing Systems (UCS2004), pp. 117-122, 2004.
[7] Hughes, J., O’Brien, J., Rodden, T.: Understanding Technology in
This is because selecting a user also causes another conflict, Domestic Environments: Lessons for Cooperative builds. In Proceedings
and remained users couldn’t be satisfied to the resolution result. of the First International workshop on cooperative buildings
Therefore, users voted for the resolution method that (CoBuild’98). Darmstadt, Germany, Heidelberg, Germany:
recommends services or contents to resolve the conflicts. With Springer-Verlag, pp. 246-261, 1998.
[8] W.Keith Edwards and Rebecca E. Grinter, “At Home with Ubiquitous
additional information, they have a chance to talk about their Computing: Seven Challenges,” LNCS 2201, pp. 256-272, 2001.
interest and reach to solution. [9] Meyer, S. and Rakotonirainy, “A survey of Research on Context-Aware
Home.”, Proc. Of the Australasian information serucrity workshop
conference on ACSW frontiers 2003, pp. 159-168, 2003.
[10] Christian Kray, Rainer Wasinger, and Gerd Kortuem, Proceedings of the
workshop on Multi-User and Ubiquitous User Interfaces (MU3I) at IUI
2004, Funchal, Madeira, Portugal, ISSN 0944-7822, pp. 7-11, 2004.
ubiPCMM 2005 57
[11] S.M. Easterbrook, E.E. Beck, J.S. goodlet, L. Plowman, M. Sharples and Research Interest: Context Awareness, Human Computer Interaction,
C.C Wood, “A survey of Empirical studies of Conflict”, CSCW: Ubiquitous/ Wearable Computing.
Cooperation of Conflicts? London: Springer-verlag, pp. 1-68, 1993
[12] McCarthy, J.F. and T.D. Anagnost (1998): “Music FX: An arbiter of
group preferences for computer supported collaborative workouts”, in Daeho Han received the B.S degree in Computer
Proceedings of CSCW ’98. Settle, WA: ACM Press. Engineering from Hanyang University in 2000 and M.S.
[13] C.Shin and W.Woo, “Conflict Resolution among Users by Utilizing degree in Computer Engineering from Hanyang
Context History”, Proceedings on ECHISE’05 held in Conjunction with University in 2002. During 2002-2005, he stayed in
PERVASIVE’05, pp. 105-110, 2005. Samsung Advanced Institute of Technology (SAIT). Now
[14] Nicholas Hanssens, Ajay Kulkarni, Rattapoom Tuchinda, and Tyler he is Samsung Electronics Digital Solution Center, Seoul,
Horton, “Building Agent-Based Intelligent Workspaces,” In ABA Korea.
Conference Proceedings, June 2002. Research Interest: Operating System, Home Network,
[15] Anind K. Dey and Gregory D. Abowd, The Context Toolkit: Aiding the Ubiquitous Computing.
Development of Context-Aware Applications, Proceedings of the
Workshop on Software Engineering for Wearable and Pervasive Woontack Woo received the B.S degree in Electrical
Computing (SEWPC), Limerick, Ireland, June 6, 2000. Engineering from Kyungbook University in 1989 and
[16] S. S. Yau, F. Karim, Y. Wang, B. Wang, and S.Gupta, “Reconfigurable M.S. degree in EE from Postech in 1991. He received
Context-Sensitive Middleware for Pervasive Computing,” IEEE Ph.D. in Electrical Engineering from university of
Pervasive Computing, joint special issue with IEEE Personal Southern California. During 1999-2001, he stayed in
Communications, 1(3), , pp.33-40, July-September. (2002) ATR Media Integration & Communications (MIC)
[17] Judd, G, Steenkiste, P., “Providing Contextual Information to Pervasive Laboratory of Japan as an Invited Researcher. Now he is
Computing Applications”, IEEE International Conference on Pervasive Assistant Professor at Gwangju Institute of Science and
Computing (PERCOM), Dallas, March 23-25. (2003) Technology (GIST) U-VR Lab., Gwangju, Korea.
[18] John Canny, Danyel fisher, “Active-Based Computing,” in Proceeding of Research Interest: 3D computer vision and its applications including attentive
CHI, The Hague, The Netherlands. (2000) AR and mediated reality, HCI, affective sensing and context-aware for
[19] S.Jang, and W.Woo, “Unified Context Describing User-Centric Situation: ubiquitous computing, etc.
Who, Where, What, When, How and Why”, the 1st Korea/ Japan Joint
workshop on Ubiquitous Computing and Network Systems, 2005.
[20] Y.Oh, C.Shin S.Jang, and W.Woo, “ubi-UCAM 2.0: Unified
Context-aware Application Model for ubiquitous computing
environments”, the 1st Korea/ Japan Joint workshop on Ubiquitous
Computing and Network Systems, 2005.
[21] S.Jung and W.Woo, " UbiTrack: Infrared-based user Tracking System for
indoor environment," ICAT'04, 1, paper 1, pp. 181-184, 2004
[22] Sj.Oh and W.Woo, “Manipulating multimedia contents with Tangible
Media Control”, LNCS(ICEC), vol.3166, pp.57-67, 2004
[23] Anand Ranganathan, Jalal Al-Muhtadi, Roy H. Campbell, Reasoning
about Uncertain Contexts in Pervasive Computing Environments.. In
IEEE Pervasive Computing, pp 62-70, Apr-June, 2004.
[24] Panu Korpipaa, Jani Mantyjarvi, Juha Kela, Haikki Keranen, and
Esko-Juhani Malm, Managing Context Information in Movile Device, In
IEEE Pervasive Computing, pp. 42-51, July-September, 2003.
[25] C.Shin, Y.Oh and W.Woo, "History-based Conflict Management for
multi users and multi services”, Proc. of 1st Workshop on Context
Modeling and Decision Support, Paris, France, July 5, 2005, ISSN
1613-0073,Vol-144.
[26] S.Jang, C.Shin, Y.Oh, and W.Woo, A introduction of “ubiHome”
Test-bed, the 1st Korea/ Japan Joint workshop on Ubiquitous Computing
and Network Systems, 2005.
[27] Y.Suh and W.Woo, User Profile Management for Context-aware
Applications in Smart Home Environments, the 1st Korea/ Japan Joint
workshop on Ubiquitous Computing and Network Systems, 2005.
[28] D.Hong and W.Woo, A Toolkit for Context-aware Application in
Wearable Computing, the 1st Korea/ Japan Joint workshop on Ubiquitous
Computing and Network Systems, 2005.
[29] http://java.sun.com/products/personaljava/
[30] http://www.nsf.or.kr
Choonsung shin received the B.S degree in Computer
Science from Soongsil University in 2004. Now he is a
M.S. student in Department of Information and
Communications, Gwangju Institute of Science and
Technology (GIST) since 2004.