Awareness in Context-Aware Information Systems Abstract

Tom Gross, Marcus Specht

GMD-FIT, St. Augustin, {tom.gross, marcus.specht}@gmd.de

Abstract

The paper describes the idea of bringing awareness to nomadic users. Based on a discussion of differentcontext models and approaches to model context, several scenarios for awareness in context-aware systemsare presented. We describe the combination of a context aware guidance system and an awareness platformto enable awareness for nomadic users about other users that are either in a similar electronic of spatialcontext. This could enhance the communication and interaction facilities for nomadic users by localisation,user modelling and an awareness platform to monitor state and events of the electronic and the physicalenvironment.

1Introduction

New technologies like wireless communication and wireless device tracking enable newtypes of applications like nomadic information systems and information appliances thatare contextualised to their current context of use.

Nomadic information systems include mobile devices as well as stationary desktopcomputers or kiosk systems, with all having access to information spaces relevant for theuser. Users will increasingly be nomads [Makimoto & Manners 1997]. Just as they alwayswear a bunch of keys in their pocket to have access to physical spaces future nomads willhave an electronic appliance to get access to information spaces no matter which devicethey currently are working with.

Awareness information environments help to support the coordination of workgroups.Typically, they provide application-independent information to geographically dispersedmembers of a workgroup about the members at the other sites such as their presence,availability, past and present activities; about shared artefacts; and about various otherthings that exist or happen at the other sites. Often they consist of sensors capturinginformation, a server that processes the information, and indicators to present theinformation to the interested users. Sensors like tracking technologies can be used to trackthe physical context of a nomadic user. This facilitates new possibilities for contextualisedservices and awareness for the nomadic user.

Several approaches from the field of location based services and location aware systemstry to integrate physical artefacts in the real world with information artefacts in theinformation space [Kanter 2000; Oppermann & Specht 2000]. The underlying idea is adirect connection of the physical space and the so-called information space where theartefacts in the physical world are connected with information artefacts in the informationspace. Context aware systems provide services and information to mobile users that areadapted to the current context of use (i.e., physical location, other persons nearby, etc.).Furthermore, the current context of the user is used to facilitate contacts andcommunication between users [Kanter 2000; Schmidt et al. 1999].

The prototypes presented in this paper try to bring these ideas together in the sense thatcontext aware systems can take into account a lot of different aspects of the current usercontext for adapting the information presented and for providing awareness about his/hercontext to a nomadic user or a third party. A location-based service can use the currentinformation about the physical environment to provide awareness to a third party. Asimple example of such a service could inform a user that one of his friends is currently inhis favourite pub. Additionally a context-aware system can take into account relations ofphysical artefacts, electronic artefacts, and similarity between users or their history ofmovements in physical or electronic space.

In the first section of this paper we will introduce some underlying ideas about our notionof awareness in context-aware systems. This will allow us to systematically describeexisting approaches that use context information for providing awareness to nomadicusers. In the following section we will introduce a nomadic guidance system and anawareness platform. By combining them we are able to implement some examples ofadvanced awareness services in nomadic information systems that will be presented in thelast section of this paper.

2

2.1

Context and Context-Aware Systems

Context in Handheld and Ubiquitous Computing

Several approaches have defined context models and described different aspects of contexttaken into account for context-aware systems. Schilit et al. [1994] have mentioned: whereyou are, who you are, and what resources are nearby. Dey and Abowd [1999] discussseveral approaches for taking into account the computing environment, the userenvironment, and the physical environment and distinguish primary and secondary contexttypes. Primary context types describe the situation of an entity and are used as indices forretrieving second level types of contextual information. In most definitions of context fourmain dimensions of a context are considered:

• Location: We consider location as a parameter that can be specified in electronic andphysical space. An artefact can have a physical position or an electronic locationdescribed by URIs or URLs. Location-based services as one type of context awareapplications [Shilit et al. 1994] can be based on a mapping between the physicalpresence of an artefact and the presentation of the corresponding electronic artefact.• Identity: The identity of a person gives access to second level contextual information.In some context-aware applications highly sophisticated user models hold and inferinformation about the user’s interests, preferences, knowledge and detailed activitylogs of physical space movements and electronic artefact manipulations. As describedin the following section the identity of a context can also be defined by the group ofpeople that shares a context.• Time: Time is an important dimension for describing a context. Beside thespecification of time in CET format categorical scales as an overlay for the timedimension are mostly used in context-aware applications (e.g., working hours vs.weekend). For nomadic information systems a process oriented approach can be timedependent (similar to a workflow).

• Environment or Activity: The environment describes the artefacts and the physicallocation of the current situation. In several projects approaches for modelling theartefacts and building taxonomies or ontology about their interrelations are used forselecting and presenting information to a user.2.2Contexts in Awareness Information Environments

As mentioned above, awareness information environments capture various types ofinformation and events from the physical world and from the electronic world and presentthe information to the members of workgroups. As these environments can potentiallyhave a big number of sensors that constantly capture a vast amount of information, somestructuring of the information is required. Furthermore, the members of the workgroupneed a common reference on the shared world—a common ground as a basis forcommunication and cooperation [Clark & Brennan 1991]. Contexts can be used tostructure awareness information and to provide users with this common reference.In general, a context can be defined as the interrelated conditions in which somethingexists or occurs [Merriam-Webster Incorporated 1999]. Gross & Prinz [2000] define anawareness context as ‘the interrelated (i.e., some kind of continuity in the broadest sense)conditions (i.e., circumstances such as time and location) in which something (e.g., a user,a group, an artefact) exists (e.g., presence of a user) or occurs (e.g., an action performedby a human or machine)‘. In awareness information environments this context informationis used to provide users with information that is related to their current context andtherefore of most value for the coordination of the group activities. In our conceptawareness contexts are described by a set of attributes (cf. Table I).

Attribute

context-namecontext-admincontext-membercontext-locationcontext-artefactcontext-appcontext-eventcontext-aclcontext-env

Description

Name of the contextHuman or non-human actor who created the contextHuman members of a context

Physical locations related to a contextArtefacts of a context

Applications related to a contextEvents relevant to a contextAccess control list of a contextRelated contexts

Table I. Attributes of awareness contexts.

These attributes are used to describe awareness contexts. For instance, an awarenesscontext could be defined for a project and would then contain the project’s name, theadministrator, who creates and maintains the awareness context; the project’s members,locations, artefacts, applications, event types such as read, write, delete, and the accesscontrol list that contains the access rights to information related to the project as well asthe relations to other awareness contexts.

According to Dey and Abowd, ‘a system is context-aware if it uses context to providerelevant information and/or services to the user, where relevancy depends on the user’stask’ [1999]. We would like to generalise this definition and extend the user’s task to

contain information about the user’s whole work context. When an event occurs, thesystem analyses to which awareness context it can be matched, adds context information,and stores it. The system then analyses the current work context of the respective user; ifthe context of the event matches with the work context of the user, the system informs theusers accordingly. So, all users who share an awareness context are informedlikewise—no matter where they are and whether they are at the same place.

3Awareness in Context-Aware Systems

3.1Electronic Space and Physical Space

Figure 1 shows a schematic representation of the real space with the physical artefactscontained, the electronic space and the electronic artefacts contained, and the users thatcan actively navigate in real space and in electronic space.

DomainModelUserModelSpace ModelFigure 1. Schematic representation or physical and electronic space.

For describing the physical space some kind of geographical model (space model) fordescribing entities in the real world and their interrelations is needed, this is shown inFigure 1 as the space model. The domain model describes the electronic artefacts in theelectronic space. All electronic artefacts and their interrelations are described herein. Inthe user model properties and the history of the user are stored. A context-awareinformation system can take into account the physical environment of a user and theproperties of a user model to select and present electronic artefacts to a user. For provingawareness in context-aware systems a model of the physical space, the electronic space,and the user model is required. In the following we will describe several single user andmultiple user scenarios where users move either in physical or electronic space. Later wewill show how context-based awareness services can be provided to them based on ourcombination of systems.

As the simplest case a single user browses the electronic space. The user model and themodel of the electronic space can be matched to provide user-adaptive informationservices. When a single user browses the physical space user tracking in physical space

can provide location-aware information selection and presentation. Furthermore a systemcan take into account the user model and the physical environment to generate adaptiverecommendations that can either recommend information artefacts or physical artefactsthat could be of special interest for the user.

When two users browse the electronic space and if both users access the same electronicentity, the system provides awareness information about their co-location. When two usersbrowse the physical space and when both users are in different places, their informationappliances provide awareness information about the other user’s current location andactivities. If both users are in the same location but at different times the system could usethe location history to provide route recommendations based on the other usersexperience.

When one user (A) explores the physical space and the other user (B) moves in electronicspace. If the location detection activates an electronic artefact for user A, which is viewedby user B, then awareness information can be given to both. If user B visits an electronicartefact, which is connected to an awareness indicator close to user A in the physicalspace, then awareness information can be given to both.

Additionally, in all scenarios the system can recommend locations or electronic entities tosimilar users based on their user model.

4Combining Context-Aware Devices and User Awareness

In the following section we will describe our starting points and main input by twoimplemented systems. HIPPIE is a nomadic information system that adapts to the Contextof Use [Oppermann & Specht 2000]. As mentioned above, ENI is an event-basedawareness environment, which includes various sensors for the capturing of events andvarious indicators for their presentation [Prinz 1999]. In the following we will introducethe basic ideas of HIPPIE and ENI and show up new possibilities that we see in theircombination.

4.1HIPPIE—A Context-Aware Nomadic Information System

Hippie is a context aware nomadic information system that supports users with locationaware information services. Beside the adaptation of information presentation andselection based on the users location the system tries to utilise the context of use foradaptation. The context of use is defined by the physical environment, the geographicalposition, social partners, user tasks, and personal characteristics. The more contextparameters are considered for the information selection and presentation, the moreeffective, efficient and satisfactory the user interaction will be. Hippie offers added valueto current information facilities by supporting all along the process of mobile activities.Process support is made possible by the nomadic characteristic of the system that allowsthe user to have access to his or her personal information space from wherever they are,independently from specific devices. The information selected and presented to the visitorreflects the location (at home or in front of an exhibit), the interests, the knowledge andthe presentation preferences of the user. Dynamic elements for animated interpretation andaudio presentations complement the visual modality preoccupied by the physicalenvironment. The user is equipped with a handheld computer and a headphone to listen to

explanations of the current artefact and environment to immerse into the subject ofinterest. The user is left alone with the physical environment, and the complementaryexplanations; via the communication function of the system, he or she can also get intouch with other individuals present in the real or virtual exhibition for appointments orsuggestions.

In the following we mention the main features of the system to explain the benefit for theusers: the process support by permanent system accessibility, the location awareness ofthe system to present information suitable to the current position of the visitor, multimodalinformation presentation to exploit the range of human perception, and informationadaptation to the user’s knowledge and interests. These features are just described shortly,for additional information see [Oppermann & Specht 2000].

Location Awareness: By infrared infrastructure the position and by an electronic compassthe direction of the visitor are identified and transmitted from the handheld computer tothe server, so that the server can automatically send the appropriate information for thevisitor. By these means, a continuous localisation of the user can be used for informationselection and be displayed on an electronic map, if the visitor user support for thenavigation in the physical space, e.g., to find a place of interest. If a new item of interest isdetected by infrared the system presents an “earcon” combined with a blinking clicksensitive “News” icon on the screen.

Multimodal Information Presentation: The system adapts the presentation of informationto the current mobile context of use. The default information presentation for visitorsduring the preparation and evaluation phases is unimodal, containing pictures and text.The default information presentation during the movement in physical space ismultimodal containing written text on the screen and spoken language via headphones,and multicodal, including text, graphics and animations. The visitor’s visual attention isfree for the physical environment. Most information is presented aurally without requiringthe user to look at the screen.

Information Adaptation to User’s Knowledge and Interest: The adaptive component runsa user model describing the knowledge and the interests of the user. The user modelcontains a history of the user’s information selection from the system and the user’sroaming in the physical space. The history is continuously evaluated for user-preferreditems or user-preferred attributes to identify particular interests comparing the user’sselection with the taxonomy of the domain. For the following presentations it can adaptthe information to the user’s assumed prior knowledge and interests. Adaptive tips provideadaptation to the assumed interests of the user. Especially his or her knowledge andunderstanding of the exhibition in general and the exhibits in particular, but also therichness of experience, which can be intensified by personalised information.

Annotation, Explanation and Communication: Hippie provides additional features tosupport the individual user and a user group moving in physical or electronic space.By the combination of features described above, Hippie makes use of Weiser’s vision,called calm technology by ubiquitous computing [Weiser 1991]. The equipment used andthe information and communication interface is designed to let the visitor walk in thephysical space while getting access to a contextualised information space tailored to theindividual needs and the current environment.

4.2TOWER—An Awareness Information Environment

Users who have to cooperate as a group need to coordinate their activities; for thiscoordination they need information. The pervasive knowledge of who is around, whatthese other users are doing, how available they are, what they are doing with electronicartefacts, and so forth is in the CSCW literature often called awareness (sometimes withprepositions such as group awareness [Begole et al. 1999; Gross to appear] or workspaceawareness [Gutwin et al. 1996]). If the cooperating individuals are at the same physicalplace this information is obvious and can be gathered easily; if individuals who are atdifferent places have to cooperate as a group technological support is essential.

We have developed an event-based awareness environment, which includes varioussensors for the capturing of events and various indicators for their presentation [Gross &Prinz 2000]. Figure 2 shows the architecture of ENI (event notification infrastructure).

IndicatorSensorIndicatorSensorpullENI-ClientpushEventdatabaseENI-ServersendCon-textmo-duleContextdatabaseCGIhttp-ServersendFigure 2. The ENI architecture.

Sensors are associated with actors, shared material, or any other artefact constituting orinfluencing a cooperative environment. Sensors can capture actions in the electronic (e.g.,changes in documents, presence of people at virtual places) and in the physical space (e.g.,movement or noise in a room). Some examples of sensors we have realised so far arepresence sensors checking for the logins of users in electronic space; web presence sensorschecking visits on Web sites; web content watchers checking updates to Web pages;sensors for office documents; and sensors for shared workspace system.

The generated events are sent to the ENI server—either via an http server or via an ENIclient. They are described as attribute-value tuples. The ENI server stores the events in anevent database. Users can use the ENI clients to subscribe to events at the ENI server andto specify indicators for the presentation of the awareness information. Subscriptions havethe form of event patterns. The client registers these patterns at the server. When theserver receives an event that matches the pattern, the event is forwarded to the respectiveclient. Additionally, users can specify how they want to be informed about the event; thatis, which indicators should be used for the presentation.

Indicators are offered in various shapes ranging from a 3D graphical presentation of amulti-user environment to pop-up windows, to applets in Web pages, to ticker tapes, andso forth. For the presentation of information in the real world ENI has some AmbientInterfaces such as a balloon, a plastic fish tank, and lamps.

The context database contains the descriptions of the awareness contexts. The contextmodule analyses the context of origin of an event and adds this information to therespective event. It also analyses the work context of the user and stores information aboutit in the context database. If the context of origin of an event and the work context of auser match, the user is informed accordingly.

A context description in ENI does not require the specification of all attributes. Forinstance, a context can be created and some attributes like locations or applications arespecified only later on; or a context could have no locations or no applications at all.Nevertheless, the more details are available for a context, the better events can be matchedto the context. In many cases the attributes of a context can be generated automatically.For instance, if a context consists of a shared workspace the list of members and artefactsof the context can be dynamically gained from information about the shared workspace.4.3

Awareness for Nomadic Users

For the purpose of supporting multiple user scenarios where an information system cantake into account sensors from physical space (like in hippie) and sensors from theelectronic space (mostly used in ENI) we combined the two systems for providingawareness to nomadic users. Taking into account a wide range of sensors in physical andelectronic space allows supporting awareness about interesting events in physical andelectronic space. As an interesting scenario to realise the combination of ENI and HIPPIEwe decided to extend an exhibition guide at Castle Birlinghoven at the GMD campus[Oppermann & Specht 2000]. In the art exhibition at Castle Birlinghoven we have around75 exhibits with multimodal information prepared for them. There is an infraredinstallation for locating visitors and different types of wearable and mobile computingdevices can be used for visiting the exhibition. Sensors for the current location and theorientation (electronic compass) of the user are attached to the mobile devices. In thisscenario we integrated the domain model of the art exhibition, the localisationinfrastructure, the user modelling component, and the awareness environment to enablenew forms of awareness in context-aware appliances.

Visitors of the exhibition can be either moving in the information space about theexhibition remotely (remote visitors) or move in Castle Birlinghoven looking at the realartworks (real visitors). When a real visitor moves in the exhibition space his mobilehippie client sends out an event about the current position, the orientation, and thephysical, and electronic entities the user interacts with. For displaying awarenessinformation remote visitors can use classical ENI clients for real visitors we are usingambient sounds in an auditory display that is overlaid with the information presentation inthe HIPPIE client. The combination of HIPPIE and ENI allows for additional scenarioswhere awareness information can be given to nomadic users:

• Real visitors moving in the exhibition can be informed about remote users looking atthe same artwork: The experience of an artwork in an exhibition could often beenhanced by discussing aspects of the artwork with experts or other visitors. In thiscase the artefact in the real world is the common cue that brings together people indifferent spaces.• Remote visitors can ask real visitors to ask questions about the artwork from a realworld perspective. An abstraction of this scenario is already used in commercial e-shopping sites, where remote visitors ask a local shopping assistant equipped with a

camera for a special view.

• Real visitors can be informed about similar tracks of previous real visitors. Thesystem keeps track of the users movements in physical and electronic space andtherefore could give information about recent visitors that took similar tracks in thephysical space.• Remote visitors can specify situations for awareness contexts in the preparation of avisit, e.g., inform me when an expert in the art of the 13th century accesses theexhibition guide either remote or real, or inform me when I pass this artwork in thereal world.These scenarios exemplify the general idea behind the combination of contexts in thephysical space and in the electronic space—that is, to combine the strength of both areas.In today’s offices users work in the physical environment with physical artefacts (e.g.,printed papers, books, received letters) and in the electronic environment with electronicartefacts (e.g., electronic documents, shared workspaces). In order to fulfil their tasks theyhave to orient in both worlds. Groupwork adds further challenges to this orientation: usershave to orient in their own physical and electronic world and need to know what is goingon in the physical and electronic world of their colleagues as well as in the shared world(e.g., physical libraries, shared electronic workspaces). A combination of HIPPIE and ENIprovides a shared frame for orientation, which allows users to coordinate their tasks and toact and react based on up-to-the-moment knowledge of the situation.

5Conclusions and Future Work

We have introduced a combination of a nomadic information system (HIPPIE) and anawareness environment (ENI) to allow for awareness of nomadic users. Combining realworld user tracking, user modelling techniques, and an event based awarenessenvironment allows us to support scenarios where real users and remote users canexperience an exhibition jointly. The prototype for supporting art exhibitions is a startingpoint and can be generalised to many useful and powerful application fields. Generallymany applications fields where nomadic users need to be aware of the state and theactivities related to electronic and physical entities to fulfil a task are a rich basis forfurther developments. Awareness information in this sense could be used to monitorcomplex multivariable processes while moving in physical space. To target this area ofactivities we will especially enhance our awareness clients based on ambient sound toenable awareness where the physical environment occupies the user’s visual sense.Because users are members of several awareness contexts and want to be informed aboutseveral awareness contexts at the same time, we need mechanisms for merginginformation from different awareness contexts and displaying it in one indicator such as aticker tape. This leads also to a problem of prioritising awareness contexts; that is, it has tobe constantly decided which kind of information from which awareness context is to bedisplayed immediately and which kind of information of which awareness context can bedisplayed after a delay. Algorithms could calculate the current actuality of an awarenesscontext form information like the number of present users (in absolute figures andrelatively to the whole number of members of an awareness context), the fluctuation of anawareness context, the frequency of changes to documents in an awareness context (either

with equally important documents or with a hierarchy of importance of documents).Furthermore, the current awareness context a user is in will vastly influence the type ofinformation to be displayed and also the means of presentation.

Furthermore the cooperation of nomadic workers shows up several needs for awarenessabout co-workers and their activities. Nomadic workers in the field can be either madeaware of remote experts for support of their field task, or of electronic artefacts likemanuals or detail information available. Cooperative problem solving in the field isanother interesting area where awareness about the activities of other nomadic workers indifferent physical locations is essential.

The ENI system is being developed in the IST-10846 project TOWER, partly funded bythe EC. We would like to thank all our colleagues from the TOWER team.

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