Context-awareness in Service-oriented Mobile ...

Context-awareness in Service-oriented Mobile Tourists Guide System Rahim A. Abbaspour and Farhad Samadzadegan Dept. of Surveying and Geomatics Eng., Engineering Faculty, University of Tehran, Tehran, Iran Tel: +98-21-8008841, Fax: +98-21-8008837 E-mail: {abaspour, samadz}@ut.ac.ir

Abstract The emergence of ubiquitous computing environment changes the service architecture of business information systems such as decision support system (DSS). Ubiquity offers new opportunities and challenges in terms of time-aware, location-aware, device-aware and personalized services which can be achieved by using customization, i.e., adapting an application towards the current context. One of the application domains particularly suited for providing ubiquitous access on basis of customization is the tourism domain, not least since in this way, tourists can be assisted not only in the preparatory phase of a vacation but especially during the vacation itself allowing access with any media, at anytime, from anywhere. Such applications supporting the tourist on the move by means of locationbased services are often called mobile tourism guides. In this paper, we propose a service-oriented architecture to develop and implement these systems.

1. Introduction Traditional and Conventional interaction between computers and users of them is somewhat poor compared to interaction between humans (users). During the physical communication between people, they do not say everything explicitly; instead it actually is based on a common context, e.g., the current situation or shared knowledge. This sort of communication and interaction reduces the amount of information necessary to see what is being talked about (Hansen, 2006). On the other hand, Computers cannot understand information in the way humans can. They can just react to the way they are programmed and the input they get from users (and this input has to be very explicit in order for the computer to handle it). Therefore users have to formulate their requests in the form of suites of commands which the computer can understand, process, and produce output in response to (Lieberman and Selker, 2000). This classical model is illustrated in Figure 1(a). So using of this scenario in computer-based decision makings force us only model the user’s explicit input information. However, computers are much better at providing output than understanding input. Whereas input has to be formulated in a nonconventional manner, output can be presented in a way that increase our capability to understand fragments of information from the context and in a language more familiar to us (e.g., using metaphors, images, animations etc.). The idea of using context in interaction is to allow the computer to tap into the context in a similar fashion as humans do and thereby make decisions about what to do, not only based on explicit user input but also on implicit input from changes in the environment(Hansen, 2006). This model is depicted in Figure 1(b). Lieberman and Selker (2000) argue that the traditional interaction model results in computer applications that are typically context-independent—the output they produce is the same no matter who is using the application, where the application is used and in which situation. The second model extends the first one and allows the application to be context-aware. This model divides interaction into explicit input and output to the user and implicit input and output to the context. Based on this input-output separation, context can be “considered to be everything that affects the computation except the explicit input and output” (Lieberman and Selker, 2000). This definition provides a good intuition about what we mean by context, especially in relation to the more traditional interaction models. In this paper, introducing the concept of context, we try to show the advantages of using the context as an additional source of information to improve decision making process. The focus of paper is on using contexts in mobile environment and as the case study, e-torism is evaluated.

(a) Context-independent application scenario

(b) Context-aware application scenario

Figure 1. Lieberman and Selker (2000)

2. Context and Context-awareness Much of the early work on context-aware systems used extensional definitions which defined context by enumerating the constituting parameters. Brown et al. (1997) enumerate “location, time of day, season of the year, and temperature”. Dey (1998) includes “information the user is attending to, emotional state, focus of attention, location and orientation, date and time of day, objects and people in the user’s environment”. Ryan et al. (1998) refer to context as “information about the environment, such as location, time, temperature or user identity”. These definitions are very topical and typically reflect the types of information that have been used by the researchers in their implementation of context-aware applications.Furthermore, as Dey (2001) argues, this kind of definitions are too specific and hard to apply when designing context-aware systems; enumerating which aspects of the context that are important is not possible since they change from situation to situation and application to application. Basing applications on enumerative definitions is likely to result in fixed models that are hard to evolve if new types of context are needed or new applications have to be implemented. Others have tried to define context more broadly by focusing on available information. Brown (1996) defines context to be “the elements of the user’s environment the computer knows about”. Hull et al. (1997) say it is “aspects of the user’s local environment”, Ward et al. (1997) refer to “the state of its (the context-aware application) surroundings”, and Pascoe (1997) define context as “any environmental factor that might influence the activities of the computer, provided there is some mechanism for capturing it”. Schmidt et al. (1999) define context as “knowledge about the user’s and IT device’s state, including surroundings, situation, and to a less extent location”. Contrary to the extensional definition, these definitions are too wide and do not offer much help for the design of context-aware applications, since we cannot model and represent everything in one framework or application. Other definitions try to capture both the general aspects of context and the relevancy of the context information. Chen and Kotz (2000) propose the following context definition: “Context is the set of environmental states and settings that either determines an application’s behavior or in which an application event occurs and is interesting to the user.” (Chen and Kotz, 2000) A similar operational definition is given by Dey et al. (2001): “Context is any information that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and applications themselves.” (Dey et al., 2001) The last two definitions are more considered in context-aware application developers’ society because they are good starting points for implementations. Firstly, they inform the design of basic technologies like data models, frameworks, infrastructures, and services and stress that these are general enough to handle any kind of data that might be regarded as context in a given application (Hansen, 2006). This means that data

models and frameworks should not just encompass a fixed set of context types (e.g., time and location), but be flexible and extensible so new and diverse types of context can be added when needed. Secondly, they focus on the relevance of the context for a specific application. Thus, using these definitions, information can be categorized as context on an application level (Hansen, 2006). The other related term in this field is context-awareness and context-aware systems and applications. Context-awareness refers to an application’s ability to react to changes in the environment and utilize context information in the computation (Hansen, 2006). Dey (2001) presents a general definition of context-aware computing: “A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on the user’s task.” (Dey, 2001) This is a good general definition, but to design context-aware applications, it is needed to specify what we mean by “uses context” and what kind of functionalities may be useful in an application. A number of efforts have tried to create categories for context-aware functions. Schilit et al. (1994) present a taxonomy of contextaware applications which is split into two orthogonal dimensions. The first dimension focuses on whether the task at hand is getting information or carrying out a command and the second dimension concentrates on whether the action is effected manually or automatically:

3. Proposed Methodology Tourism is an information intensive business. Since tourism products are virtual products prior to consumption, travelers depend heavily on tourism information for planning purposes and decision making before their trip. After their trip, focus is on reminiscing about the journey and sharing the gained impressions and experiences with friends. With the emergence of mobile technology, supporting tourists also during their trip is feasible. Especially in this situation tourists act in unknown environments and would need personalized on-trip assistance in form of information about accommodation, points of interest (POIs) (e.g., environmental and landscape attractions or gastronomy), weather forecasts, news or safety issues. According to the general definition of context, we may recognize the required elements of it in activities and use cases related to a mobile tourist guide system. We propose a five category framework which consists of location, time, user, system and environment (Figure 2). Each of these categories covers some elements. For example, the “time” category includes daily time, sunrise and sunset time, day of week and month, month of year, calendar information (such as vocations, celebrations, etc).

Figure 2. Context and its Categories

Much research has been done in the field of using mobile technology in tourism industry. Closely related to the research topic is the field of mobile online communities and mobile tourist guides. Focus of the former is particularly on porting online community features to the mobile environment. The latter comprises applications supporting the tourist on the move by means of context-aware services. Schwinger et al. have a comprehensive survey on most of the current mobile tourist guides in depth from context and

its adaptation points of view (Schwinger et. al 2005). In the current systems, the interaction between user and the system are based on conventional client-server architecture in which it is not based on the services. In this paper, we propose to build a context-aware tourist guides based on services. To implement the system, we propose a service oriented architecture (SOA) to respond the request of user. The key component in the SOA is services (Erl, 2005). A service is well defined set of actions. It is self contained, stateless, and does not depend on the state of other services. Stateless means that each time a consumer interacts with a service, an action is performed. After the results of the service invocation have been returned, the action is finished. There are three types of key actors in SOA, these are service requestor (the tourist in our case), service provider and service matchmaker (which help the requestors to find the right services). When a tourist requests a service, the requestors and service brokers need to collaborate to find the right services. After the right service is found, requestor and provider negotiate as to format of the request and some other protocol issues. After all the requestor can access and invoke services of the provider (bind). Figure 3 illustrate the proposed architecture.

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Context

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Figure 3. the proposed architecture to build a context-aware tourist guide system

4. Conclusions Emerging technologies such as pervasive and ubiquitous computing have changed the use of GISs, moving them from the office desktops into the users’ hands. Due to this mobility, the context information play a key role during the decision making process. One of the popular application areas of these systems is in tourism industry where the location and motion are of great importance. In this paper, we proposed a new service-oriented architecture to use the context information in mobile tourist guide systems to enable them to present the users more suitable services. The implementation of a pilot system based on proposed methodology is under construction as the complementary phases of this work.

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