Journal of Software Engineering and Applications, 2011, 4, 268-281
doi:10.4236/jsea.2011.44030 Published Online April 2011 (
Copyright © 2011 SciRes. JSEA
Generic Framework for Context-Aware
Communication Services in Visitor’s Guides
Tsvi Kuflik1, Pnina Soffer1, Iris Reinhartz-Berger1, Sadek Jbara1, Oliviero Stock2
1Department of Information Systems, University of Haifa, Haifa, Israel; 2FBK-irst, Trento, Italy.
Email: {tsvikak, sp nin a, iri s}@, sjbara@gmail . com,
Received April 2nd, 2011; revised April 12th, 2011; accepted April 21st, 2011.
Ubiquitous computing plays an increasing role in our lives. Typically, applications in ubiquitous computing environ-
ments are context aware, namely, they react to the situations of their users at a given moment in time. One example for
such environment is visitors guides in cultural heritage sites, supporting visits of individuals or small groups, such as
families or friends. In such environments, it is well known that interaction among visitors enhances the overall visit
experience. Recently, some research prototypes of visitors guides have started supporting such interaction through
textual communication services embedded in them. However, these applications have so far been developed separately
in an ad-hoc mann er, despite common features and infrastructures they share. The research described here generalizes
communication services offered by different visitors guides and suggests a systematic and generic framework for de-
veloping context-aware communication services for visitors guides. The specific communication services are ab-
stracted into a d omain model, later used in pra ctice for adapting and tailoring the differen t concepts to the specific re-
quirements of the applications. The framework is demon strated in the specific setting of a multi-ag ent museum visitors
guide system. We also show that the suggested framework is not limited to the specific museum visitors guide system
but may facilitate the development of context-aware communication applications in general.
Keywords: Communication Services, Context Aware Communication, Visitors Guides, Domain Analysis
1. Introduction
In the past decad e, when mobile technology h as matured
enough, many research prototypes of context aware mo-
bile tour guides and museum visitor’s guides appeared,
aimed at providing museum visitors with personalized
and context aware information. Most of the works fo-
cused on exploring how the novel technology can be ap-
plied for supporting individuals, mainly by providing
context aware information and navigation support to vis-
itors in museums [1-6]. In many cases, these systems sup-
ported also interaction among visitors by providing them
with some communication services. For example, Ran-
tanen et al. [7] suggested enab ling users to “post” virtual
messages for each other's attention at specific physical
Interaction among museum visitors is known to en-
hance the visit experience [8]. Moreover, since a group
visit is a common form in museums [9-11] and other cu-
ltural heritage sites, the focus of the research now turns
to supporting groups in these places [12,13]. In such sce-
narios, technology-supported communication between
museums visitors enables them to interact even when
they are not in close proximity. As such, communication
services should be considered not as a minor add-on, but
as a central group-supporting service in the applications.
Context awareness of such services makes them an in-
tegral part of the vi si t expe ri ence for groups.
To the best of our knowledge, all the works done so far
in the area of context aware communication services have
developed each service separately in an ad-hoc manner.
This makes the development of each service a considera-
ble effort, and limits the variety of services that can be
offered by a specific system. We claim that these services
can be considered a domain that exhibits a large variety
of features, fulfilling different needs, but with common
features that characterize all or most services in the do-
main. Since all these communication services share com-
mon basic characteristics, and possibly a common infra-
structure, it would be reasonable to utilize the commo-
nalities and all the possib le variations and provide a basis
over which specific services can be easily developed. An
easy development process will facilitate the inclusion of
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
a variety of communication services in Visitor’s Guide
systems. Following this idea, this paper addresses contex t
aware communication services in a systemic way, through
domain analysis. While there is an abundance of research
about context awareness in general, we focus on the
com-munication services themselves. To this end, a ge-
neric framework for defining and implementing context
aware communication services has been developed, pro-
viding a configurable infrastructure, which can be tai-
lored to meet the various needs and requirements of spe-
cific communication services. The framework has been
implemented and demonstrated in an “active museum”
environment, which is one example of a visitor’s guide.
The environment is composed of a physical space con-
taining exhibits and computation equipment (communi-
cation infrastructure, computers, presentation devices,
etc.). Specifically, the framework was applied within a
multi-agent museum visitor’s guide system, developed as
a part of the PIL1 project, an Italian-Israeli research col-
laboration project dealing with Personal Experience with
Active Cultural Heritage.
The rest of the paper is structured as follows. Section 2
provides the background for the current research and
reviews related work. Section 3 introduces the suggested
framework for defining context-aware communication
services, developed through analyzing the domain of in-
terest. Section 4 reports an implementation of the frame-
work in a museum visitor’s guide system, whereas Sec-
tion 5 evaluates this framework through application case
studies. Conclusions and future research directions are
given in Section 6.
2. Background and Related Work
This section provides background about context-aware
services and applications in general, and communication
services in visitor’s guides in particular. It motivates our
work on context aware communication services and is a
basis for gener a l i zat i on.
2.1. Context Aware Services and Applications
Defining “Context” is a challenging task. Many resear-
ches in the area of context awareness tried to define the
context of a user in a way suited to their application
needs. Dey et al. [14] claim that “while most people ta-
citly understand what context is, they find it hard to elu-
cidate”. They defined context as “any information that
can be used to characterize the situation of an entity”,
whereas an entity is defined as “a person, place, or object
that is considered relevant to the interaction between a
user and an application, including the user and applica-
tions themselves”. This definition of context can be spe-
cialized when dealing with a specific application or a fa-
mily of applications. For example, Roffia [15] speciali-
zed context definition to mobile cultural heritage applica-
tions, stating that “context is a coordinate’s pair, named
physical and logical coordinates. The physical coordinate
represents the curren t user’s position and orientation. The
logical coordinate represents information on the level of
detail explicitly provided by the user.”
A context-aware service is a service which uses con-
text-related information and adapts itself to the changes
of user’s and environment’s context dynamically and
automatically. A large number of context aware applica-
tions have been proposed under the vision of ubiquitous
computing in general and visitor’s guides in particular.
An early example of con-text-aware computing is the
Olivetti Active Badge system [16]. Based on emitted in-
frared signals from a badge, the system determined users
location information. The most common usage of the
system was by a receptionist who routinely used it while
forwarding telephone calls from the main switchboard.
The receptionist would look at the display of locations
and then redirect the telephone call to the correct loca-
In the cultural heritage domain, th e “Guide” pr oject [17 ]
provided an electronic handheld guide that enabled visi-
tors to Lancaster access city information, create tailored
city tours, and access interactive services, such as mak-
ing ticket reservatio ns or booking hotel accommodatio ns.
It also included communication services among visitors,
reviewed later on in this paper.
Context aware systems can also use physiological sen-
sors like in StartleCam [18], developed at MIT media lab.
This system is composed of a wearable video camera, a
computer, and a sensing system, enabling the camera to
be controlled via both conscious and preconscious events
involving the wearer. A skin conductivity signal is mea-
sured, related to the attention level. Traditionally, a wea-
rer consciously hits record on the video camera, or runs a
computer script to trigger the camera according to some
prespecified frequency. The system offers an additional
option: images are saved by the system when it detects
certain events of supposed interest to the wearer.
Developing context aware application is not easy and
it draws a lot of research attention in recent years, as
demonstrated by numerous conferences and workshops
addressing this issue. Many attempts were made to pro-
vide generic infrastructure for general context aware ap-
plication development (to list just a few, see [14,19-24],
some even for the specific setting of cultural heritage
sites [25,26]. However, most of them focused on context
modeling and infrastructure, rather than on the services
themselves. Conversely, we focus on communication
services, assuming that an application can use one of the
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
existing context modeling tools.
2.2. Communication Services in Visitor’s Guides
Context aware communication services have been in-
cluded in various systems and especially in mobile con-
text aware museums and city guides. Since such services
are the focus of interest in our work, we surveyed 55
mobile tourist guide systems developed from the early
1990s until recently, only with respect to these services.
Twelve of them provide textual communication services,
which are of particular relevance to museums, where
voice-based communication might not be welcomed.
These systems are presented and discussed below in de-
tail (grouped by type, in chronological order). They serve
as a basis for analyzing and defining the domain of in-
2.2.1. City Guides
The Campiello system [27,28] aims to encourage the
creation of connected communities in cultural towns.
Using paper-based interfaces, Campiello enables the vis-
itors to add information to a personal diary. These pages
can be printed or faxed in order to be processed later.
Furthermore, people can post their paper forms to large
screens, and they can immediately view the newest input
to the system together with others, to get immediate
feedback on their input.
Smart Sight [29] is a voice activated tourist gu ide sys-
tem. It provides its visitors with “Tourist Diary” to help
them organize their trip experience. When the tourist
arrives at a point of interest, the system logs the position
and time retrieved from the GPS and system clock. The
tourist can ask the system to take a pictur e or digital vid-
eo clip, and to add captions to the picture or dictate the
description or comments during his/her visit at the point
of interest. After the tourist finishes visiting the site or
the day ends, he/she can ask the system to generate an
HTML document based on the stored information.
GUIDE [17,30] an electronic handheld tour guide al-
ready introduced in Section 2.1, provides its users with
personalized location aware information. It also enables
visitors to send and receive messages to/from compa-
nions, sharing their experiences with others.
LoL@ [31] is a mobile electronic tour guide designed
for tourists visiting the city center of Vienna. It provides
predefined tours through the city center, information
about the sights, navigation and routing, and an electron-
ic tour diary. All visited places are automatically in-
cluded in a tour diary stored on the application provider’s
server. Additionally, users can include comments and
private data like digital photographs. The diary can be
retrieved after returning from the trip and can be ac-
cessed by people staying at home during the trip. As fu-
ture work the authors suggest to consider immediate
messages to be sent between visitors during their tour
(real time tour reporting).
2.2.2. Museum Guides
CyberGuide [1,32] is a mobile, context aware tour guide
that allows its users to send messages to exhibit owners
and to report their location to a central server, accessible
by others.
Hippie [33] is a nomadic museum guide developed
within the HIPS (Hyper-Interaction within the Physical
Space) project [34]. It allows its users to take notes and
annotate visited exhibits in order to store personal expla-
nations or bookmarks av ailable during the visit. It fu rther
supports sending immediate messages that can be di-
rected to a dedicated addressee, such as family or group
members in a museum, or to a specified full e-mail ad-
dress, to contact a remote user.
Exploratorium Guidebook [35], a location aware visi-
tor’s guide developed for the Exploratorium in San Fran-
cisco2, provides two communication functionalities,
named “rememberer” and “communicator”. The first one
provides the visito rs with means to build a reco rd of their
experiences which they can consult during and after their
visit, while the second one helps visitors communicate by
electronic bulletin boards for individual exhib its, instant-
messaging, and/or beaming information between hand-
held devices. The researchers conclude that their remem-
bering service may have value for personal and social
uses. They also conclude that people seem to enjoy help-
ing each other and discussing the exhibits, and this seems
to encourag e additional interaction with the exhibits.
MUSE [36], a location aware museum guide, allows
visitors to mark the currently disp layed screen or to use a
built-in camera to take a picture of what they are look ing
at and update a “visit memory album”. At any time, ei-
ther during or at the end of the visit, the visitors can mo-
dify the memory album by deleting some selected items,
re-ordering them, or includ ing co mments and annotatio ns.
The final album can be saved on CDs, which represent
the “memory” of the on-site visits.
Virtual Heritage [37] is the focus of a research that ex-
plores the possibility of using virtual reality in order to
enrich visitors experience on sites. The system also al-
lows visitors to take notes and exchange information
with peers in a chat-like mechanism.
MOMO [38] allows visitors to communicate and send
messages to other visitors, and to see the names of visi-
tors that already visited a specific artwork, in order to
share similar interests at the museum or to keep in touch
more easily. The researchers claim that the messaging
feature is the main poin t of the social interaction because
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
it allows visitors to communicate and to interact with the
rest of the museum visitors, either by sending messages
individually or by sending the same message to all the
members of a group.
The exSite museum visitor’s guide, made by ESPRO3,
offers MyCollection, a service that allows its users to
mark artworks of interest and select later on objects to be
printed at the museum shop.
2.2.3. Mess a gi ng Se rvi ces
InfoRadar [7] provides public and private location-based
messaging and a novel radar interface for accessing mes-
sages, where nearby messages can be tracked in the mo-
bile device on a map. Such messages have an expiry time
and visibility, and can be viewed remotely if the recipient
is unlikely to visit the location of the message. The In-
foRadar package contains a compact-size digital camera
that can be connected via infrared to the InfoRadar main
device and allows the users to attach a picture to a mes-
sage being composed.
2.2.4. Summary of Communication Services Suppor t
in Visitor’s Guides
In summary, after reviewing 55 mobile visitor’s guides,
we found that about 20% of them (i.e., 12 systems) pro-
vide text-based communication services to their users.
Table 1 presents the classification of these systems ac-
cording to the types of commu nication services they pro-
vide and the contextual aspects they consider: an imme-
diate message sent to a recipiant, a virtual “Post-It” left at
a location (e.g., personalized Geo-Note), or a “memory”
—message to self (e.g., personal diary entry). The pre-
vailing contextual aspects found in the cultural heritage
guides involve Spatial, Temporal and Social aspects,
whereas the contextualized information is an adaptation
of the information deliv ered to the visitors based on con-
textual aspects.
As can be seen, the various applications, which repre-
sent a variety of communications services suggested by
Visitor’s Guides, share some common features, but each
has its uniqueness too. Looking at the services, most of
them can be categorized either as immediate messages or
diary-like applications and some applications provide
more than one type of communication services. As far as
contextual aspects, most of them are location aware,
where about half provide contextualized information.
Most of them also have some form of social awareness
(that is tightly coupled with communication services). In
the following section we use all this info rmation in order
to get a generalized view of the domain under cons idera-
Table 1. Classification of the reviewed systems according to
communication service types* and type of context.
service* Type of Context
Info. Spatial Temp.Soc.
City Guides
Campiello# XX X
Smart Sight X X X X
Museum Guides
CyberGuide X X X
GuideBook XX X X X
Virtual HeritageX
exSite X X
serv. InfoRadar X X X X
*Immediate (I), Post it (P) or Diary (D); #The type of context in the service
provided by Campiello is not specif ic, and depends on the user’s cho ice
3. A Generic Framework for Developing
Context Aware Communication Services
As noted, the variety of systems is quite large. However,
some guidelines constraining their common features can
be outlined. First, each communication service has one
sender and potentially several recipients, one of which
may be the sender (e.g., in diary communication ser-
vices). In most cases, the sender and recipient are all us-
ers or visitors using the system to be developed and they
are usually identified by IPs and/or names. The commu-
nication service itself is characterized by its name, sub-
ject, sending time, and the content to be sent.
Each user (or visitor) may have different context attri-
butes in various time periods. As already noted, these
context attributes can be divided into four categories:
1) Contextualized Information includes general attri-
butes regarding the visiting environment that the user
(visitor) is exposed to, including physical objects and
presentations. In active museums, the physical objects
may be exhibits, and the presentations may be audio or
video files about exhibits and exhibitions.
2) Spatial Context includes the current location and
movement of the visitor. The spatial context is charac-
terized by the area, the specific location (e.g., a specific
exhibition in an active museum), direction (of move-
ment), orientation (indicating where the visitor focus is
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
and possibly the general view, and speed.
3) Temporal Context includes attributes such as cur-
rent time, visit phase, phase start time, and visit duration.
4) Social Context refers to groups of users (visitors)
and to the particular role of a user in the group, as well as
aspects such as attitude and mood.
Even if we do not use explicitly the term “cognitive
context” it is clear we mean (and other systems may also
implicitly aim) to take into account the physical and the
perceptive, epistemic and possibly emotional state of the
visitor. We have chosen this level of representation to
accommodate various experiences; and also for our own
work (see the following) we prefer not to be bound to a
specific model, but just to propose the generic elements
that can then be used at a higher level to provide a char-
acterization of the cognitive context.
Note that the context of a particular visitor changes
over time during the visit. Furthermore, potentially, a
user can change groups during the visit. Thus, context
aware communication services should be able to refer to
the current and past context of their users, both senders
and recipients. Examples of involving contextual aspects
of the sender include adding to a communication service
the location of the sender or information regarding his/
her group. Considering the context of a recipient, mes-
sages, for instance, are not sent to a recipient who has
already visited the exhibit or left the museum. For sup-
porting these, each context aware communication service
is connected to different context objects, representing
conditions on the sender, the recipients, and the envi-
ronment. These context objects may be embedded in the
service as contextual conditions and/or contextualized
content. Contextual conditions define constraints on the
delivery of a given message. They usually use at least the
context of the recipient. Contextualized content, on the
other hand, usually refers to the sender’s context to be in-
cluded in the message.
Contextual conditions can be further divided into pre-
sent and future contextual conditions. Evaluation of pre-
sent contextual conditions at run time determines wheth-
er the message should be sent or not. They are evaluated
once at delivery time. Future contextual conditions, on
the other hand, should be dynamically evaluated with
every change in contextualized data. Messages that have
future contextual conditions will be delivered as soon as
their (future) contextual conditions are satisfied. Regard-
ing the types of messages defined above, immediate mes-
sages have no future con textual conditions, whereas post-
it services must have such conditions. Note that diary
services are characterized by the equality between their
sender and recipient. Tabl e 2 exemplifies how to specify
context aware communication services in the suggested
framework, whereas Figure 1 depicts the domain model
of the suggested framework, expressed as a class di agram.
Note that in general the domain model includes con-
cepts that are not specific to visitor’s guides. The only
part that is specific to visitor’s guides is the specialized
context (con textualized info rmation, spatial co ntext, tem-
poral context, and social co ntext). In addition, th e specia-
lized context aware communication services in the model
(i.e., immediate, post-it, and diary) rely on our analysis,
which was done for that area. Hence, this list may not be
complete when considering other application areas.
4. Implementation of the Generic
Framework in Active Museums
As seen in the domain model, there exists a solid com-
mon basis to the various communication services that can
be offered in visitor’s guides. We propose to utilize this
understanding of the commonality and variability to en-
able easy development of a variety of services that may
be required by different applications. These services will
be provided by configuring a common and generic com-
munication service infrastructure. This way, when spe-
cific applications are developed, specific communica-
tion services can be rapidly provided as configurations of
the generic service. Such architecture can streamline the
development process of new applications that require
Table 2. Context aware communication services in the suggested framework.
Communication Service T* present condition# future condition content
Send a message to all the users in the sender’s group
who have not visited the area in which the sender is
visiting now, calling them to visit this area I Group (recipient) = Group (sender)
AND NOT Area (sender) in
VisitHistory. Area (recipient) Area (sender)
Send a message to all the users in the sender’s group
who have not visited the exhibit the sender is visiting
now to watch this exhibit as soon as they enter its
area, but only if this happens in the next 5 minutes
P Group (recipient) = Group(sender )
AND NOT Exhibit (sender) in
VisitHistory. Exhibit (rec ipient)
Area (recipient) = Area
(sender) AND Current
Time (recipient)
Message.SentTime + 5
Exhibit (sender)
Remind the sender regarding the area in which he/she
is visiting now D sender = recipient Area (sender)
*Immediate ( I) , P ost it (P) or Diary (D); #VisitHistory refers to the past c ontext of a user (sender or re cipient).
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
Figure 1. A domain model of context aware communication services in visitor’s guides.
context aware communication services.
Considering museum visitor’s guides as a wide and
interesting sub-area of visitor’s guides, we have develo-
ped a tool that allows its users (application developers) to
define and implement communication services to be used
as part of their applications automatically. The specific
communication services are specialized classes, defined
as configurations of the generic context aware communi-
cation service class from Figure 1. These service classes
are defined using a Service Configuration tool which
yields XML files, specifying the exact configuration of
the communication services at hand (including their con-
textual conditions and their contextual content). The
XML definition files are then used as inputs by a Com-
munication Generator tool that generates the specific
services for the used communication infrastructure. Nev-
ertheless, the user interface and the actual logic of each
generated communication service have to be developed
individually to meet the particular requirements of the
service. In our case, the services themselves are generat-
ed as agents in a multi-agent system that has been devel-
oped as part of the PIL project [13], a multi-agent mu-
seum visitor’s guide system. This system uses Loud-
Voice agents’ communication infrastructure [39,40] and
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
contains five components (see Figure 2): 1) a Spatial In-
formation Broker that reports the visitor’s positio n perio-
dically, integrating positioning information from differ-
ent sources (currently Infrared and WiFi); 2) a Presenta-
tion Composer that provides presentations to the visitor,
based on the current location and taking into account the
visitors’ inferred preferences; 3) a User Modeler agent
that keeps track of the visitors’ preferences based on their
behavior; 4) a Communication Services Agent that pro-
vides communication services to the visitors; and 5) a
User Assistant (Device Interface) agent which is installed
on the user’s PDA and provides the user interface to the
system (information presentation/user actions).
For specific service definitions, the “communication
services generator” interprets the XML communication
definitions and generates the required communication
services as specialized agents. Note that the generic ser-
vice idea is not limited to a specific infrastructure. It can
be implemented as a web service, over a multi-agent
communication infrastructure, or through other commu-
nication mechanisms. In general, it can be implemented
over any communication infrastructure that supports the
definition of the generic model, as will be discussed later
to show the generality of the framework.
The communication service development and usage
process includes four consequential p arts, participating in
different life-cycle stages and depicted in Figure 3:
1) At design time, the communication services, as re-
quired by the application, are defined using the Commu-
nication Service Definition tool, producing an XML
communication services definition file.
2) At application development time, specific applica-
tion that includes the code for using the communication
activities (usually user interface that will use the com-
munication service) is developed. It includes requests for
sending or receiving services as defined by the XML
configuration file (at design time).
3) At runtime initialization stage, the communication
services are automatically created by the communication
service generator, ba sed on the XML-b ased conf igur ation
file produced at design time.
4) After initialization of runtime, active users utilize
the communication services through the user interfaces.
Any operation, either sending or reading a specific mes-
sage is invoked by a user activating the appropriate ap-
plication that was developed for this specific communi-
cation service. The communication itself as well as the
collection and interpretation of contextual information
required for the service are provided by the generic in-
5. Demonstration and Evaluation of the
Generic Framework
This section demonstrates the usage of our generic
framework in four communication services: SMS (i.e.,
immediate messages), Post-It, Memories (i.e., diary), and
Visit Reminder (also diary) services. Then, we evaluate
the generality of the framework by showing how it can
be applied to produce the services reviewed in Section 2.
5.1. Demonstration: SMS and Post It-Like
We start with presenting the implementation of two ser-
vices which have already been integrated into the PIL
system, namely the SMS and Post it-like services. While
SMS is a relatively simple immediate message service,
the virtual post-it service is more complicated, with a
major role to context awareness. The implementation in-
Figure 2. The museum visitor’s guide architecture in PIL.
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
Figure 3. The suggested communication service development and usage process.
cluded the possibility to select and send a message from
a set of predefined messages. This is important in this
case since museum visitors should focus their attention
on the exhibits and not on the guide itself.
5.1.1. Requirements and Usage Scenar io s
The SMS-like messages can be classified as immediate
messages. The requirements from this type of services
are that messages should be delivered immediately after
sending, taking into account the current context of the
sender and optionally of the recipient. In the PIL project,
when the user is in a certain position, next to a specific
exhibit and wants to send a message to a friend, the user
selects a message from a list of predefined ones, includ-
ing: 1) “You should see this exhibit”, 2) “You should
visit this area”, 3) “You should skip this area”, and 4)
“Could you please come here?” (Without giving any
specific details) If, for example, the sender selects the
message “you should see this exhibit”, the message will
be delivered to a recipien t if he/she has not yet visited th e
sender’s current exhibit, and the information about “this
exhibit”, like its name and an image, will be added au-
tomatically by the system to the delivered message. This
information may possibly include a path on a map that
leads the recipient to the sender’s location as well (since
the two positions, this of the sending user and this of the
recipient are known to the system).
Like SMS, Post-It services are context-based virtual
notes whose delivery depends on the context of the send-
er and recipient. Unlike SMS, the post-it note may be
virtually attached to an exhibit that the sender is looking
at, and the message will be delivered to the recipients
only when and if they visit this ex hibit (and optionally if
additional contextual conditions are fulfilled). Post-It
services may take into account the visit history of the
recipient, the current context of the sender, and the social
context of both sender and recipient. The content of a
delivered message is enhanced by the sender’s current
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
contextual information. As an example to a Post-It note
consider: “Remember this exh ibit—I’d like to talk to you
about it later”. The message will be delivered to the reci-
pient if he/she arrives at the sender’s (current) location
within a given time period (the message expiry time),
and if he/she has not yet visited the sender’s current ex-
hibit. Furthermore, information about “this exhibit” will
be added to the message. This information will suggest
the recipient to choose the exhibit recommended by the
sender when (and if) visiting the location where the post-
it is attached.
5.1.2. Configuration Pr ocess
In order to define these two services, fulfilling the abov e
requirements, the developer of an application configures
a generic communication service, using a configuration
tool developed for this purpose The result of the process
is an XML definition file, where each communication
service is defined as a class element with a unique iden-
tifier and two sub-elements, conditions and content. Fig-
ure 4 represent s the SMS de finition fil e .
The conditions element includes information on pre-
sent and future conditions to handle the current commu-
nication service, as well as possibility to initializing va-
riable values needed for defining contextual content or
conditions. The SMS configuratio n file (Figure 4) inclu-
des only present conditions, specifying that the recipient
should be in the sender’s group and has not visited the
area the sender is currently visiting. The Post-It configu-
ration file includes both present and future conditions.
The present conditions require that the recipient is in the
sender’s group and has not visited the exhibit the sender
is currently visiting; future conditions specify that the
message has to be delivered to a recipient that arrives at
the area the sender is currently in within 5 minutes.
The content element includes the contextual element in
the actual content of the communication service. The
SMS service should augment the area of the sender
(name, picture) into the message, while the Post-It mes-
sage should include the exhibit information (current ex-
hibit of the sender). The XML file is used during system
initialization to generate the relevant communication
services, as described below.
5.1.3. Runtime Ap plicati on
In addition to the configuration definition file, an appro-
priate user interface for these services has been devel-
oped. For the SMS service, the application is executed in
runtime based on the user’s selection of a predefined
message (listed at the beginning of Section 5.1.1, and on
the second screen from left in Figure 5).
At initialization time, i.e., when the system is initia-
lized, communication service agents are created follow-
ing the definitions in the configuration file for every
logged-in user. At runtime, while the visitors are using
the guide, they can press the button of the envelope (the
icon in the left bottom of Figure 5) in order to open
a list of predefined text messages (Figure 5, second
screen from the left). After the sender chooses the de-
sired message from the list (“you shou ld see this exhibit”
in this case), a list of other visitors’ names appears (Fig-
ure 5, third screen from the left) to enable the sender to
choose the actual recipients (one or all). A final screen
includes the text message and recipient names to confirm
sending (Figure 5, rightmost screen). In the example the
sender recommends the recipient to see the exhibit at
which she is currently looking.
Upon delivery, a button at th e bottom of th e screen no-
tifies a recipient that a message is received (the icon
in Figure 6, left screen). If he/she chooses to read the
message by pressing the button, then a list of sender
names appears (Figure 6, second screen from the left),
and when one is selected, a list of messages sent by that
visitor is presented (Figure 6, third screen from the left).
Finally, after choosing one of the messages, a new screen
with the delivered message appears. Recall that the con-
tent of the delivered message depends on the sender’s
context. Specifically, the phrase “this exhibit” is replaced
with the name of the exhibit that was recommended by
the sender, and an image of this exhibit is added to the
message (Figure 6, rightmost screen).
Runtime application of the Post-It service is similar to
that of the SMS, with the following differences. First, the
list of possible messages is slightly different (see Figure
7 left side). In the given list, messages 4 and 5 match the
configuration specified in Figure 5, where the message is
attached to an Area and bearing the information of an
Exhibit in that area as its content. In contrast, the first
three messages (1, 2, and 3) relate to a slightly different
configuration. These messages are supposed to be at-
tached to an Exhibit rather than to an Area, and their
content provides a recommendation about some Presen-
tations rather than Exhibits. This would mean different
<class id="send">
Condition ="(Group (sen der)==Group(recipient s ))
AND (NOT(X(sender) in Y(recipients)))"
FutureCondition = "null"
VariablesInit = "X=Area, Y=History[Area]"/>
<Content attrs = "X(sender)"/>
Figure 4. The XML configuration file for the SMS-like im-
mediate message service.
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
Figure 5. Sending a context aware immediate message.
Figure 6. Receiving a context aware immediate message.
default values given to the variables X, Y, and Z in the
XML configuration file (X = Presentation, Y = History
[Presentation], Z = Exhibit).
5.2. New Services Implemented as Proof-of
In addition to the above described SMS-like and Post-It
services, two other services, Memories and Visit Remin-
der, were simulated using the generic framework, but not
implemented as part of the visitor’s guide system.
The Memories service adds contextual information
about the environment to the visitor’s annotations; the
contextual information may refer to any type of object,
such as exhibition, area, exhibit, and presentation. It ena-
bles the visitor to write comments in free text about ob-
jects of different types in the museum. This service is
classified as a diary service.
The “Visit Reminder” service, which is also a diary
service, provides a sequence of reminder services. Before
the visit starts, the visitors may choose a list of locations
that they plan to see during the visit within a specific
time frame. The service has the goal to remind them
“Don’t miss” what they planned to see or listen to within
the predefined time frame.
5.3. Assessing the Generality of the Framework
Above, we described four services which have been im-
plemented or simulated on the basis of the proposed
framework. This framework allows users to easily define
and implement communication services in various appli-
cations, without the need to worry about the specific te-
chnical details, as demonstrated by the application des-
cribed earlier. To assess our claim that this framework
supports a wide range of communication services, we
follow a descriptive evaluation method, called scenarios
[41], which requires constructing detailed scenarios
around the suggested artifact (the generic framework in
our case) to demonstrate its utility.
In particular, Table 3 show s how the sugg ested frame-
work supports all the communication services that were
provided by the 12 systems reviewed in Section 2. The
second column describes the communication services as
provided by the different systems (Imm abbreviates im-
mediate messages). Columns three to six describe how
the same service can be defined using the generic frame-
work and the last column comments on the status of the
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
Table 3. Implementation of the various communication services using the generic framework.
System Comm. Service T* present conditioncontent Comments
Taking notes D sender = recipient none Information is recorded first
Publishing them to all the
visitors I None none
Then it may be presented over a large screen to
all visitors—the presentation is part of the
Smart sight Keeping a tour diary D sender = recipient Exhibit ( se nd er),
Area (sender),
Visit Phase (sender)
Specific visited locations and time are recorded.
Creating the tour diary its elf is left to the
application developer.
Guide Sending messages to
group members I Group (recipient) =
Group(sender) none Very brief description of communication services
Automatically adding
visited points of intere st t o
a tour diary, stored on the
provider’s server
D Sender = recipientArea (sender)
Contextualized messages are sent to “self”. The
created diary includes the l ocations visited.
Creation of the Album is left to the application
developer. The information may be viewed by
others as well.
Sending messages to
group members I Group (recipient) =
Group(sender) none Immediate messages to group members are in
future work.
Sending messages to
exhibit owner I none Exhibit (sender)
Context aware communication services are
desired, but not implemented in the system.
Sending messages to
visitors I Group (recipient) =
Group(sender) Area (sender)
Taking notes on p oi nts of
interest D sender = recipient Area (sender) Notes can be added to presentations.
Sending messages to other
group members I Group (recipient) =
Group(sender) none Immediate messages can be sent to friends.
Rememberer: keeps a visit
record D sender = recipient Exhibit (sender) Specific visited physical obje cts are recorded.
Communicator: Instant
messaging I None
No detailed description is pro vided. Messa ges are
sent to “friends”.
Memories channel:
marking exhibits of
interest or taking digital
D sender = recipient Area (sender)
Contextualized messages can be sent to “self”,
where the current presentation is marked and
recorded. Linking and editing are part of the
application development.
Virtual Heritage D sender = recipient No detailed d e sc ription is provided. A text editor
is used for taking notes
Momo Instant messaging between
group members I Group (recipient) =
Group (sender) There is no deta iled des cription of the features.
exSite Marking exhibits of
interest for use at the
museum shop D sender = recipient Exhibit (sender) It allows marking specific physical objects
Info Radar Leaving and reading
location-based messages P None Area (sender)
Messages are attached to locations. Can be
sent/read remotely
*D-diary, I-im mediate, P-post it.
services’ implementation and what remains for the appli-
cation developer’s responsibility. Empty cells mean that
there was not enough information about the service to
determine its contextual conditions or content.
Looking at the different rows of the table, we can see
how every service in the reviewed systems can be im-
plemented using the generic framework. The diary ser-
vices, for example, namely those in Campiello, SmartSite,
LOL@, HIPPIE, Exploratorium, GuideBook, MUSE, and
exSite, are all characterized by a contextual present con-
dition specifying that the sender equals to the recipient
and no contextual future condition.
While the first characterization is essential to all diary
services, the absence of contextual future condition is a
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
matter of current reality: no system has yet implemented
a diary service with post-it capabilities (e.g., a personal
reminder service). Furthermore, all diary services in the
reviewed systems partially support spatial context (in the
form of area) and contextualized information (in the form
of exhibits); they do not support temporal neither social
context awareness.
Regarding immediate messages, one can see that the
reviewed systems are at most social aware (referring to
the sender’s and recipient’s groups) while delivering the
messages. In addition, the messages themselves may
contain spatial context (in the form of area) and contex-
tualized information (in th e form of exhibits). Our frame-
work can provide more sophisticated immediate messag-
ing (e.g., sending messages only to the visitors who have
not yet been at the location of the sender are currently at
a specific location). Finally, the post-it service of Info
Radar refers to the location (area) of the recipient, with
respect to the sender, and embeds spatial-related and con-
textualized information in the message to be sent. Again,
while our generic framework supports these services, it is
also capable of supporting more complicated post-it me-
While the basic context aware communication mecha-
nisms are common, the applications themselves differ. As
a result, a large variety of applications can be developed
using the suggested framework. Note that the contextual
conditions used in all the reviewed systems are quite sim-
ple and only partially use the attributes proposed by our
Another dimension of the generality of our framework
is its independence of the underlying infrastructure type.
The configuration is expressed by means of an XML file,
which makes it possible to use with different kinds of
infrastructures over which these applications can be de-
veloped. Yet, it requires an interpreting componen t, as an
interface with the infrastructure.
6. Conclusions and Future Work
Context aware communication services can play an im-
portant role in supporting visitors in cultural heritage
sites, as demonstrated by the abundance of related work
that exists. Our work shows that although there may be
many “flavors” to communication services, they all share
a small set of common characteristics. This calls for a
standard definition of such services that can be applied in
any application, so developers can define the specific
“flavor” of services according to their system require-
ments, while reusing the common, generic infrastructure.
The framework suggested in this paper focuses on
communication services. It defines two dimensions for
classifying context aware communication services: the
communication service type (namely immediate, post-it,
or diary) and the supported context type (i.e., contextua-
lized information, spatial context, temporal context, and
social context). Given the abundance of context aware
toolkits, it is possible to use any context management tool
kit that can provide the required contextual data.
This framework has been implemented using two main
components: a service configuration tool and a generic
communication generator tool. The generic communica-
tion service relies on the LoudVoice multi-agent system.
However, specific application components that tailor user
interfaces to the communication services have to be de-
veloped separately for each communication service type.
Since our conceptual framework is not dependent on a
specific communication solution, future work will focus
on developing a web service-based “Communication
Generator” to allow applying the newly suggested frame-
work to a widely used technology.
Although analyzed and ev aluated in the context of Vis-
itor’s Guides, the suggested framework aims at facilitat-
ing the development of context-aware communication
services in general, which nowadays is considered to be a
complex and time-consuming task due to the lack of an
adequate infrastructure support [42]. Furthermore, consi-
dering the increasing number of applications providing
context-aware communication services to their users and
the heterogeneity of communication services which an
application may use, such a framework can be genera-
lized for context-aware communication services in active
environments in general. Furthermore, the contextual as-
pects can be extended to include, for instance, cognitive
context of the senders and recipients, which includes their
believed knowledge at a certain time. Indeed, this kind of
context may partially be addressed in the current frame-
work by relating to the visit history and assuming it
represents what the visitor knows. In order to address a
richer range of contextual aspects, developers may con-
sider using a generic tool like the tool developed by [14]
and others, and by doing so to focus on application speci-
fic aspects, rather than developing ad-hoc context aware
communication services.
As for the futur e, we may use the framewo rk presented
here and apply it to context aware applications in general.
Consider, for example, the area of context-aware shop-
ping recommendations. Different applications can be
developed in this domain, such as location-aware recom-
mendation or recommendation of products that are sup-
plementary to a product recently bought. These applica-
tions, as well as others, may share a common infrastruc-
ture. Similarly to our framework, a service configuration
tool can be designed and implemented in that area. Such
service configuration tool would build on a domain mod-
el which captures the unique features and relevant con-
textual attributes in that domain, and would streamline
Generic Framework for Context-Aware Communication Services in Visitor’s Guides
Copyright © 2011 SciRes. JSEA
the development of such applications.
7. Acknowledgements
The research was supported by the collaboration project
between the Caesarea-Rothschild Institute at the Univer-
sity of Haifa and FBK/irst in Trento and by FIRB project
RBIN045PXH. Experimentation was conducted at the
Hecht museum at the University of Haifa, Israel.
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