Abstract
A smart card runtime environment must provide the proper transaction support for the reliable update of data, especially on multiapplication cards like the Java Card. The transaction mechanism must meet the demands by the applications and the system itself within the minimal resources offered by current smart card hardware. This paper presents the current transaction model implied by the Java Card 2.1 specification, highlights its shortcomings and presents a detailed discussion of possible implementation schemes and their optimizations. It especially addresses the problem of object instantiations within a transaction in the Java Card 2.1 specification and presents an effective solution.