Ⅰ NCREASED DEMANDS attention in dynamic environments can be addressed tbrough interfaces that requre less attention account during the commerce applications design process and within the boundaries of Context hanged slowly (if at all) this context model will be after system completion presented here, followed With the advent of Environment by ways to address them noble an vices, context is a less pre How Context Affects dictable influence on the ommerce actual design and use of Many activiti omputer systems. People for a user's attention on Participants|← Activities the Web. There are set environments that are rel- vices sending news sto- tively unstable from one moment to the next Future prices, and notific In mobile and ubie of email messages uitous computing, the Past least with wired e-com notion of context is merce. the environment often equated simpl outside of the Web is with location but is actually more complex. Mobile Graphical representation of fairly stable from day to application use can vary continuously because day. Most offices and changing circumstances and differing user needs. A homes function with a context model, depicted in the figure here, can be good amount of predictability, even if they experi created using three broad categories of context: envi- ence a great amount of activity, and relatively consis- ronment, participants, and activities. The environ- tent amounts of attention can be devoted to mentcategory is concerned with the properties of performing tasks on the computer. objects in the physical environment. Participants" In the realm of m-commerce, conversely, there us of the user(s) and other partici- can be a significant number of additional people pants in the environment. Activities" covers user, objects, and activities vying for a user's attention participant, and environmental activities. Addition- aside from the application itself. Furthermore, ally, the model includes any interactions or relation- since devices are completely mobile, this outside ships that may exist among participants, activities, environment can change rapidly from moment to ncorporated into this model, allowing for a context user may be trying to juggle history that can be used for predicting future context. mobile device along with other elements in the This context model builds on the strengths of previ- environment. The amount of attention a user can ously proposed models [1, 7, 8]. Severa al challenges give to a mobile application will vary over time, (summarized in Table 2)that arise when designing m- and a user's priorities can also change unpre 58 December 2003/Vol 46, No 12 COMMUNICATIONS OF THE ACM58 December 2003/Vol. 46, No. 12 COMMUNICATIONS OF THE ACM account during the design process and changed slowly (if at all) after system completion. With the advent of mobile and wireless de￾vices, context is a less pre￾dictable influence on the actual design and use of computer systems. People are using applications in environments that are rel￾atively unstable from one moment to the next. In mobile and ubiq￾uitous computing, the notion of context is often equated simply with location but is actually more complex. Mobile application use can vary continuously because of changing circumstances and differing user needs. A context model, depicted in the figure here, can be created using three broad categories of context: envi￾ronment, participants, and activities. The “environ￾ment” category is concerned with the properties of objects in the physical environment. “Participants” includes the status of the user(s) and other partici￾pants in the environment. “Activities” covers user, participant, and environmental activities. Addition￾ally, the model includes any interactions or relation￾ships that may exist among participants, activities, and the environment. Table 1 summarizes several con￾text characteristics for each category. Time is also incorporated into this model, allowing for a context history that can be used for predicting future context. This context model builds on the strengths of previ￾ously proposed models [1, 7, 8]. Several challenges (summarized in Table 2) that arise when designing m￾commerce applications within the boundaries of this context model will be presented here, followed by ways to address them. How Context Affects M-Commerce Many activities compete for a user’s attention on the Web. There are ser￾vices sending news sto￾ries, alerts about stock prices, and notifications of email messages. But at least with wired e-com￾merce, the environment outside of the Web is fairly stable from day to day. Most offices and homes function with a good amount of predictability, even if they experi￾ence a great amount of activity, and relatively consis￾tent amounts of attention can be devoted to performing tasks on the computer. In the realm of m-commerce, conversely, there can be a significant number of additional people, objects, and activities vying for a user’s attention aside from the application itself. Furthermore, since devices are completely mobile, this outside environment can change rapidly from moment to moment. An m-commerce application may not be the focal point of the user’s current activities, as the user may be trying to juggle interaction with a mobile device along with other elements in the environment. The amount of attention a user can give to a mobile application will vary over time, and a user’s priorities can also change unpre￾INCREASED DEMANDS on users’ attention in dynamic environments can be addressed through interfaces that require less attention. Context Environment Interactions Participants Activities Future Present Past Graphical representation of context model