Marcus Oestreicher

JavaCard-from hype to reality

In this final of three related articles about smart card technology, the authors discuss the JavaCard, a much-hyped technology that is finally taking off as a multiapplication smart card. The main reason for the hype is JavaCards potential. Not only would it let all Java programmers develop smart card code, but such code could be downloaded to cards that have already been issued to customers.

Mote Runner: A Multi-language Virtual Machine for Small Embedded Devices

This paper introduces a new virtual machine for sensor networks and small embedded devices which has been designed with efficient resource usage and an event-driven programming model in mind. The virtual machine runs on 8, 16, and 32-bit micro-controllers with as little as 4KBof volatile and 32 KB of non-volatile memory. Our virtual machine is not bound to a single high-level programming language, but targets all strictly-typed programming languages.In conjunction with the virtual machine, we also present our development tool chain for Java and C#, and discuss the effects of our virtual machine design on these high-level languages. We also present a compact load-file format which allows applications to be stream-linked in a way that minimizes memory usage and bandwidth. All presented components are part of the IBM Mote Runner, a run-time environment for wireless sensor networks.

Transactions in Java Card

A smart-card run-time environment must provide proper transaction support for the reliable updating of data, especially on multi-application cards like the Java Card. The transaction mechanism must meet these demands by means of 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.