System integration for mobile computing and service mobility
In future networks, mobile computers will become increasingly important. Distributed, mobile applications enable information access anywhere, anytime. Mobility, location independence and adequate information access will be supported simultaneously. Major problems due to mobility and the specific characteristics of portable computers and wireless communications are dynamic configuration, moving resources, reachability, data and functional consistency. In this paper we present a system caUed
... DICK that addresses the problems of mobile computing. The requirements and solutions for service mobility are described in detail. Mobile computing systems allow to access and to distribute information at any time and anywhere. New portable computers and wireless communications technologies particularly enable mobile computing. Additionally, many system integration effects have to be addressed to support mobile users and mobile computing applications. There are at least three important issues that determine mobile computing systems: • A basic but far-reaching fact is that the users are moving and thus the topology of the system is dynamically changing. This includes user-and terminal mobility. A. Schill et al. (eds.), Distributed Platforms © Springer Science+Business Media Dordrecht 1996 Mobile computing and service mobility 45 • The mobile terminals will always be less powerful than the stationary computers. Thus we have a performance disparity between the mobile and stationary computers. That has a strong influence on the system design, e.g., workload balance, etc. • The data rates of wireless connections will always be clearly lower than those of wired connections. Additionally, wireless connections are not as reliable as wired. Major problems due to mobility and the specific characteristics of portable computers and wireless communications are dynamic configuration, moving resources, reachability, data and function consistency. These problems have to be treated in more than one of the communication layers. A full system architecture is necessary to support mobile users and mobile computing applications (DiHe 94, DGH 94, Dieh 95). Additionally security aspects are very important. User management and work flow management are necessary to support concrete applications and work flows with mobile users. This paper discusses selected aspects of mobile computing. Section 2 discusses general aspects of sysrtem integration. In section 3 we introduce MOBI-DICK (MOBIle Data InterChange Kit) a system to support distributed mobile applications. Section 4 gives an example, how service mobility is supported. Finally, in Section 6 our test system is described. SYSTEM ISSUES OF MOBILE COMPUTING In the following we discuss several new challenges that are important when designing systems with mobile users (see also Weis 93, DiRe 94, DGH 94, ImBa94 and Dieh 95).