Impact of mobility on information systems and information system design [Elektronische Ressource] / von Peter Ahlbrecht

Impact of Mobility on Information Systemsand Information System DesignVom Fachbereich fur Mathematik und Informatikder Technischen Universit at Braunschweiggenehmigte Dissertationzur Erlangung des Grades einesDoktor-Ingenieurs (Dr.-Ing.)vonDipl.-Inform. Peter Ahlbrecht1. Referent: Prof. Dr. H.-D. Ehrich2.t: Prof. Dr. I. Ramos SalavertEingereicht am: 17. September 2004Mundlic he Prufung am: 10. November 2004PrefaceIn the context of this dissertation, information systems are viewed as softwaresystems o ering a number of information services based on a typically large datarepository. More speci cally , an system is viewed as a reactive, pos-sibly distributed system consisting of one or more large data sources, usually inthe form of data bases, plus applications built on top of these.In most applications, information systems are stationary, not only in the sensethat the databases are bound to xed locations, but also in the sense that they areaccessed from xed locations, i.e., via computers which are bound to a networkand have an invariant position in the topology of that network. A typical exampleis a travel booking system with access from travel agencies all over the country.However, a growing number of applications require that access to informationcan move with the user, and the access conditions and also the expected responsesare location dependent. Typical examples are handheld devices giving contextdependent travel information, e.g.