MyGuide: A Mobile Context-Aware Exhibit Guide System Jongmyung Choi1 and Jongbae Moon2 1
Dept. of Computer Engineering, Mokpo National University, 61 Cheonggye, Muan-gun, Jeonnam, 534-729, Korea
[email protected] 2 Korea Institute of Science and Technology Information (KISTI) 52-11, Eoeun-dong, Yuseong-gu, Daejeon, 305-806, Korea
[email protected]
Abstract. Recently there have been researches on smart exhibition guide systems for visitor’s convenience. In this paper, we introduce a context-aware, visitor-oriented guide system and some context related issues encountered during the development process. Our system provides a visitor with the most suitable guide information on the exhibit in both its content and its media format. For visitor-oriented guide service, we adopt four types of context information: visitor’s location, visitor’s background knowledge, media type supported by the terminal device, and visitor’s preferred language. We also show how to model context in an object-oriented approach, how to apply ECAM software architecture to our system, and how to build our prototype system using RFID, MIDP APIs, and context-awareness. Keywords: Context-aware, Guide system, Mobile, RFID.
1 Introduction In museums and in exhibitions such as the Consumer Electronics Show (CES) [1], visitors need more customized guide systems rather than brochures or notes on the exhibit. For visitors’ convenience, guide systems have advanced from brochures to digitalized systems. Recently, these digitalized guide systems have tended to adopt mobile devices, such as PDAs and mobile phones, and context-awareness for personalized services [2-7]. The main feature of these systems is that they focus on the visitor’s convenience and needs. As the result, they have focused their interests on two kinds of technologies: services on mobile devices and location-awareness. However, they don’t consider the visitor’s background or profile, and provide the same information. In real world, some visitors may want more advanced and detailed information on the exhibits, while others may want simple and general information. In addition, some may want dynamic multimedia content, but others may want simple but quick text contents. In addition to the visitor’s convenience, the visitor-oriented service that considers a visitor’s background is also very important for the visitor’s satisfaction. Therefore, smart guide system should be able to provide visitor-oriented guide services. O. Gervasi et al. (Eds.): ICCSA 2008, Part II, LNCS 5073, pp. 348–359, 2008. © Springer-Verlag Berlin Heidelberg 2008
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In this paper, we introduce a context-aware, visitor-oriented mobile guide system, named MyGuide. We adopt three kinds of technologies: RFID, mobile phone, and context-awareness to support the visitor’s convenience. For the visitor-oriented guide service, our system considers three types of context information: the visitor’s background knowledge, the media type supported by his/her mobile device, and his/her preferred language. With these three contextual elements, the visitor’s location constitutes the context of our system. These context data determine the contents of the guide information and the media format. We also introduce our prototype system and our experiences learned during the development process. In the early phase, we acquire the requirements from the stakeholders and identify the four contextual elements from these requirements. After that, we model context with the four contextual elements in object-oriented approach, and determine the software architecture. We adopt ECAM (Event, Control, Action, Model) architecture pattern [8] for our system because of its event-driven feature. We also design the system based on the software architecture and the database schema. In the implementation phase, we use MIDP [9] for the mobile phone programming, 13.56 MHz RFID reader and GNU java serial library [10] for RF tag reading, Oracle database for context information management, and Darwin Streaming Server [11] for multimedia services. The main contributions of our work are four. First, we propose a visitor-oriented guide system that considers the visitor’s background. It considers the visitor’s knowledge level, media type, and preferred language, and determines the guide contents based on these data. Second, we adopt four types of context information for the guide services. Most of context-aware systems use single context information. However as the systems become more complex, they will use multiple types of context information more frequently. Third, we introduce how to model context with orthogonal context information in an object-oriented way. In the perspective of context-aware services, context is categorized into two: Multimedia and Text. Fourth, we show the development phase and the prototype system in detail. This will be a guideline or a sample for further context-aware system development. The remainder of the paper is organized as follows. In Section 2, we discuss other works that are closely related to our work. Then we introduce some interesting issues on developing context-aware guide systems including system requirements, contextual elements, context modeling, and system architecture in Section 3. After that, in Section 4 we introduce our prototype system. Finally, we reveal the conclusions of our work in Section 5.
2 Related Works Recently, there have been studies on smart guide system to serve museums and exhibitions. The main features of these systems are location-awareness and mobile devices. The representative studies are the researches of Keith [2,12], Sherry [3,4], and Jani [5]. Keith [2,12] introduces a city tour guide system that utilizes a wireless network and context-awareness. The system was initially intended to adopt three different types of context information: location, display device, and user profile [2], but its implementation uses only location [12]. The system determines the user’s location using the location information from the base station.
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Sherry [3,4] introduces an exhibition guide system using RFID. The main feature of this system is its bookmarking function. It means that visitors can bookmark any exhibit that draws his/her interests, and then he/she can make web pages with the information about the exhibits. Jani [5] introduces an RFID-based system, mTag, which provides information to the pre-specified devices when the user carrying a tag approaches the RFID reader. The mTag system is similar to our system in that they both provide information when a tag approaches the fixed RFID reader. Other representative systems in the field are the guide system of National Museum [6] and the system of the science exhibition [7] in Korea. These guide system use mobile phone and mobile RFID. The existing researches and systems have some similarities with our system, but our system also has its own uniqueness. The differences and similarities of the systems are described in Table 1. MyGuide system uses multiple types of context information and supports the visitor-oriented guide services. Table 1. Comparison of Smart Guide Systems
Attributes Context Location Terminal Visitor-oriented Systems Information Sensing Device Service Keith’s [12] Location Base station PDA No Sherry’s [3][4] Location RFID PDA No Jani’s [5] Location RFID PDA No Museum[6][7] Location Mobile RFID Mobile Phone No RFID Mobile Phone Yes MyGuide Location, Knowledge, Media type, Language
3 Context-Aware Guide Systems 3.1 System Overview Very diverse guide systems such as brochures, books, audio systems, and human guides have been utilized in the exhibition shows and museums. The main goal of MyGuide is to provide the most suitable information to the visitors in the most suitable format. In the requirements elicitation phase, we acquire the basic requirements as specified in section 3.2. In addition, we choose RFID, mobile phone, and contextawareness to meet the requirements. If we use these technologies, the visitors can receive the most suitable services as in the following scenario. Scenario When a visitor arrives at the museum, he/she registers his/her information (background knowledge, language) and his/her mobile phone information (facilities, phone number), and receives an RF tag. After registration, the visitor walks around the exhibits, finds an interesting exhibit, and accesses the RF tag to the reader attached to the exhibit. Then the system sends a message to the visitor. The message contains the information about the exhibit, or the URL for the multimedia information about the exhibit.
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If we follow this scenario, we can generate the sequence diagram as shown in Fig. 1. We can figure out RFID reader, database for context information, contextserver, and contents server from the scenario. The RFID reader sends the tag value to the context server, and it identifies the visitor. After that, it also can access context information stored in the context database using the tag value as a key. The contents server keeps the explanatory contents about the exhibits, and provides suitable contents to the visitor.
Fig. 1. Sequence Diagram for Scenario
From the basic scenario and the sequence diagram, we determine the overall architecture of the system. Fig. 2 shows the overall architecture of MyGuide system. When a visitor approached to the exhibit, the context server determines the context, and contents server provides guide information through CDMA network.
Fig. 2. Overall Architecture of MyGuide System
3.2 System Requirements and Development Strategy From the goal and the scenario of MyGuide, we are able to draw the functional and non-functional requirements. The followings are the representative requirements for the system.
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• (R1) Customized Services: Existing guide systems provide the same services to all visitors without considering the visitors’ background knowledge or age. This can feel unsatisfactory to the visitors. Children and beginners don’t understand the explanation with jargon, and experts are not satisfactory with an explanation that contains only general information. Therefore, our system considers the visitors’ background and provides appropriate information according to their profiles. • (R2) Easy Use: The end-system or terminal should be easy to use, and the visitors should feel comfortable using the technology. • (R3) Personal Usage: The visitor should be able to get and control the services at any time when he/she wants in the museum. • (R4) Multimedia Services: Our system should be able to deliver multimedia data to the visitors. Multimedia content is very effective to explain information to a visitor whether he/she is a child or an adult, or a beginner or an expert. On the other hand, if the terminal does not support multimedia service, it should be able to provide text data at least. • (R5) Less Cost: Our system should be implemented with the least costs and efforts because of limited budgets. Therefore, we prefer to use the existing technologies without developing new technologies. • (R6) Multiple Languages: One of the interesting requirements from stakeholders is for the system to support multiple languages as the number of visitors from other countries increases. Therefore, our system should support guide contents in multiple languages. We searched the possible technologies available to meet the basic requirements, and we chose RFID, mobile phone, and context-awareness strategically. There are several reasons why we choose these technologies as follows; • RFID: An RF tag is small enough to carry with the visitor and it is natural and easy to use. It is a stable technology because it has been used in various fields for a long time. Furthermore, there are ample system components and software modules for RFID systems, so we can reduce costs and efforts by using the existing components instead of developing them from the scratch. • Mobile Phone: In order to support mobility, we need mobile devices including PDA, mobile phone, and other dedicated mobile terminals. From several kinds of devices, we choose mobile phone based on the following merits. First, most of the new products support multimedia display, and even older ones support at least a text message service without adding any hardware components or installing any software modules. Second, we can save cost and effort in developing end-systems for providing guide service. Third, the mobile phones are easy to carry and people tend to keep their phones with them. Fourth, they are user friendly. It is their own phone, and they use it every day. Fifth, a mobile phone is always connected to a CDMA or GSM network at any place. We don’t need to consider a situation in which the end-system is disconnected. • Context-awareness: Day[13] defines context as “any information that characterizes the entity”. Context-aware systems adjust their services according to the context. We think the visitor’s profile and location are good examples for context information. Based on these data, our system determines its service contents.
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These technologies are stable and popular in their own fields. We only need to combine them to meet our functional requirements. 3.3 Contextual Elements In the scenario of Section 3.1, we assume two things. First, the system database has a table that maps the exhibit and the RFID reader’s identifiers. Therefore, we can get the visitor’s location when a reader reads his/her RF tag. Second, the visitor registers his/her information with an RF tag value. There are countless environmental elements around the context-aware system. However we cannot consider every contextual element, so that we limit the number of contextual elements in our system to the information that is necessary to meet the requirements. We identify four kinds of context information that affects the service of our system. • The visitor's location • The visitor's background knowledge • The facilities of the visitor's mobile phone • The visitor's preferred language The visitor's location is primary context information. The system can determine which exhibit draws a visitor’s attention according to his/her location. We use RF tags and RFID readers to identify the visitor’s location. When the visitor with an RF tag approaches to an exhibit, the reader attached to the exhibit identifies his/her tag value. In the perspective of guide information, the location determines the subject of data to be served. Considering the visitor's background knowledge is the most valuable feature of our system. The more we divide the level of the background knowledge, the more the service will be satisfactory. However, we should consider development costs and the maintenance problem of contents, so that we group the background knowledge into three levels. •Beginning: basic information for children and those unfamiliar with the subject •Normal: general information for ordinary adults and middle/high-school students •Advanced: advanced information for experts or college students The facilities of the visitor’s mobile phone determine the media type of information. Some phones support multimedia data display, but others may have the only minimum functions for mobile phone. Therefore our system should consider the facilities of the visitor’s mobile phone. We therefore categorize mobile phones into two types: Text or Multimedia. The visitor's preferred language is also important context information to be considered. As the world becomes smaller, we need to serve the visitors from other countries in museum. We consider total three languages: Korean, English, and Chinese. The four kinds of context information have their own set of possible values as specified above. A situation in our system is the value combination of four kinds of context information. And the value of context information determines the contents and the media format of the guide information.
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3.4 Context Modeling MyGuide adopts four kinds of context information for its services. The notable feature of them is that they are orthogonal and independent of each other. For example, the visitor’s location has nothing to do with his/her preferred language, and the subject and the language of the contents have nothing in common. The four types of context information can be represented orthogonally in the four-dimensional coordinate as shown in Fig. 3.
Fig. 3. Context Space of MyGuide System
According to Dey’s definition [13], each of the four types of context information can be a context, but any one, two, or three of them cannot determine the guide service. Therefore, we view a context as the combination of all constituent context information. In our system, we define a context as the tuple of values of the four context information types. Then, a context may be represented as a dot in the coordinate system in Fig. 3. In MyGuide system, we have too many contexts. Let C be the set of all possible contexts in MyGuide system. Then a context c ( C) can be represented as a tuple: c = , where loc Loc, level Level, dev Dev, and lang Lang. We can imagine that Loc = { x | x is an exhibit. }, Dev = {multimedia, text}, Lang = {Korean, English, Chinese}, and Level = {beginning, normal, advanced}. Then we can calculate the number of contexts in MyGuide as follows: | C | = | Loc | x | Dev | x | Lang | x | Level | Because this system has too many contexts to consider, we need to categorize them according to commonality and variability. In MyGuide system, media type determines the metadata and service server, so we categorize context information according to media type. Fig. 4 shows the context model of MyGuide. The notation used in the figure follows our prior studies [14, 15]. The notation is similar to class diagram. According to this notation, a context may be implemented in multiple ways, so that it is represented as an interface. Similar contexts have common features, and the common features can be generated as context type. MyGuide has two contexts: Multimedia and Text. We have four kinds of context information and two contexts. Therefore, when the system senses the contextual data from the external environment or from the internal source, it should be able to gather the data, interpret the data, and generate contexts. We call the component that plays the roles as the context reducer. Fig. 5 shows the context reducer.
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Fig. 4. MyGuide Context Model
Fig. 5. Context Reducer
3.5 Software Architecture Software architecture is important enough to determine the system’s framework and design. Compared to traditional systems, context-aware systems have some additional interesting features to consider in determining software architecture. Therefore, there have been interesting studies for architecture patterns for context-aware systems. We adopts ECAM (Event, Control, Action, Model) pattern [8] for MyGuide because it is event-driven and it uses multiple kinds of context information. ECAM is the extension of the ECA (Event, Control, Action) [16] pattern by adding Model for context information. In ECAM pattern as shown in Fig. 6, TagReader reads the RF tag and generates a READ event. The event is transferred to the Controller in Control, and Context in Model. Context gathers context information from multiple sources and determines the current context of the system. Context in ECAM plays the role of context reducer in Fig. 5. Controller determines the service contents based on the Service Descriptor and the current context determined by Context. Then the Controller transfers the information about the service to ActionManager. ActionManager provides the service.
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Fig. 6. ECAM Architecture
4 Prototype System We implemented MyGuide prototype system on the Microsoft Window platform. We chose the Java language for software implementation, and MIDP [9] for mobile phone programming. We used 13.56 MHz RFID readers and card-type RF tags. We used GNU java serial communication library [10] to connect to the RFID readers. For multimedia service, we adopted Darwin Streaming Server from Apple [11]. We managed the context information and the guide data on the exhibits in Oracle 10g DBMS. Fig. 7 shows the architecture of the prototype system and its components.
Fig. 7. Architecture of MyGuide Prototype System
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MyGuide starts services on READ event from RFID reader. The visitor’s profile and his/her mobile phone information are stored in DBMS. Fig. 8 shows the E-R diagram of the prototype system. Contents entity means the guide data for an exhibit. For an exhibit, there are several Contents records to provide visitors with suitable data. Visit entity means the trace data of a visitor’s access to the exhibits.
Fig. 8. E-R Diagram of MyGuide Prototype System
The class diagram of MyGuide is shown in Fig. 9. TagManager gets the values stored in the RF tag and the reader’s identifier, and generates READ event. On the event, the Controller takes the control and coordinates the cooperation between CntxtReducer and MsgSender. CntxtReducer infers the current context from the values of contextual elements. It uses DbFacade for retrieving contextual data stored in DBMS. Controller determines the contents of service using the context, and asks MsgSender to generate Msg for the service and send it to the visitor. Msg consists of the explanation of the exhibit and the metadata.
Fig. 9. Class Diagram of MyGuide Prototype System
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Fig. 10 and Fig. 11 show the running examples of MyGuide prototype system. Fig. 10 shows the text service at beginning level in Korean. Fig. 11 shows the multimedia service at beginning level in Korean.
Fig. 10. Text Service
Fig. 11. Multimedia Service
5 Conclusions Exhibitions and the museums actively adopt information and communication technologies to provide convenient services to the visitors in preparation for the ubiquitous computing era. However, until now existing systems haven’t considered the visitor’s background. Therefore, the guide services have not been truly visitor-oriented. In this paper, we introduced a mobile guide system for exhibitions and museums. The most interesting feature of the system is context-awareness. It considers four kinds of context information: location, background knowledge, media type, and language. Based on the context information, the system provides the most suitable services to the visitor. For example, when a Korean visitor is an expert on the exhibit, and he/she has a mobile phone that supports multimedia, the system provides the multimedia type expert information in Korean. We also introduced some interesting issues when developing context-aware systems: system requirements, context information, context modeling, software architecture, and its prototype system. We drew system requirements from stakeholders during the informal interview. From the requirements, we chose three basic technologies for the system: RFID, mobile phone, and context-awareness. We also found out the four types of context information. Because the context data are independent each other, there are too many possible contexts. Therefore, we model context from context information and determine two kinds of contexts. We chose ECAM architecture pattern for our system because it is event-driven and it can handle multiple kinds of context information. Our prototype system is implemented with 13.56MHz RFID reader, Darwin Streaming server, and MIDP APIs. The current version is running on the MIDP emulator, and we will port it to run on the mobile phone in the near future.
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References 1. Consumer Electronics Show, http://www.cesweb.org/ 2. Cheverst, K., et al.: Developing a Context-aware Electronic Tourist Guide: Some Issues and Experiences. CHI Letter 2(1), 17–24 (2000) 3. Hsi, S.: The Electronic Guidebook: A Study of User Experiences using Mobile Web Content in a Museum Setting. In: Proc. of the IEEE International Workshop on Wireless and Mobile Technologies in Education (2002) 4. Hsi, S., Fait, H.: RFID Enhances Visitors’ Museum Experience at the Exploratorium. Comm. of the ACM 48(9), 60–65 (2005) 5. Korhonen, J., et al.: mTag - Architecture for Discovering Location Specific Mobile Web Services Using RFID and Its Evaluation with Two Case Studies. In: Proc. of AICT-ICIW, pp. 191–200 (2006) 6. Lee, E.: [Experience Mobile] PDA Video Guide System in National Central Musem, mtalk (December 2005), http://m-talk.inews24.com/ 7. Kim, E.: Listing from mobile phone in Science Exhibition, mbn (November 14, 2007), http://news.mk.co.kr/ 8. Choi, J., et al.: Context Model for RFID Systems. In: Proc. of 2nd International Conference on Ubiquitous Information Technologies and Applications (2007) 9. Mobile Information Device Profile (MIDP), http://java.sun.com/products/midp/ 10. RXTX, http://www.rxtx.org/ 11. Open Source Streaming Server, http://developer.apple.com/opensource/server/streaming/ 12. Cheverst, K., et al.: Experiences of Developing and Deploying a Context-Aware Tourist Guide: The GUIDE Project. In: MOBICOM, pp. 20–31 (2000) 13. Dey, A.K.: Understanding and Using Context, Personal and Ubiquitous Computing. Special issue on Situated Interaction and Ubiquitous Computing (2001) 14. Choi, J., Park, J.-S.: Context Issues in RFID Systems. In: Proc. of ALPIT (2007) 15. Choi, J.: Context-Driven Requirements Analysis. In: Gervasi, O., Gavrilova, M.L. (eds.) ICCSA 2007, Part III. LNCS, vol. 4707, pp. 739–748. Springer, Heidelberg (2007) 16. Dockhorn Costa, P., Ferreira Pires, L., van Sinderen, M.: Architectural Patterns for Context-Aware Services Platforms. In: Proc. of the Second International Workshop on Ubiquitous Computing (2005)
