This assignment has been performed at location and commissioned by Attendit AB in Jönköping. The task has been to develop a client/server system to access data stored in SQL databases where the client application is developed to run on regular cellular telephones. The importance has been to develop as reliable mobile communication as possible. The functionality that is demanded upon the mobile communication is: • Secured for future versions • Interoperability • Data should not be bugged, modified or disappear unnoticed • Resource efficient We have achieved these demands by developing our own protocol that is on top of the TCP protocol. The difficulty with the development has been to take in mind the limited resources of the mobile phones re...