One of the biggest challenges in future application development is device heterogeneity. In the future, we expect to see a rich variety of computing devices that can run applications. These devices have different capabilities in processors, memory, networking, screen sizes, input methods, and software libraries. We also expect that future users are likely to own many types of devices. Depending on users ’ changing situations and environments, they may choose to switch from one type of device to another that brings the best combination of application functionality and device mobility (size, weight, etc.). Based on this scenario, we have designed and implemented a seamless application framework called the Roam system that can both assist developers to build multi-platform applications that can run on heterogeneous devices and allow a user to move/migrate a running application among heterogeneous devices in an effortless manner. The Roam system is based on partitioning of an application into components and it automatically selects the most appropriate adaptation strategy at the component level for a target platform. To evaluate our system, we have created several multi-platform Roam applications including a Chess game, a Connect4 game, and a shopping aid application. We also provide measurements on application performance and describe our experience with application development in the Roam system. Our experience shows that it is relatively easy to port existing applications to the Roam system and runtime application migration latency is within a few seconds and acceptable to most non real-time applications. 1

The third generation mobile devices will provide more and more features and as well, more and more security considerations. Sun Microsystems has announced their platform for such devices: Java 2 Micro Edition. J2ME provides portable application environment for the customer and embedded systems, including mobile devices. A user having a J2ME mobile device can download applications from open network and run them on his/her mobile device. A open network is also untrusted network.