SyD: A Middleware Testbed for Collaborative Applications over Small Heterogeneous Devices and Data Stores

Currently, it is possible to develop a collaborative application running on a collection of heterogeneous, possibly mobile, devices, each potentially hosting data stores, using existing middleware technologies such as JXTA, BREW, compact .NET and J2ME. However, they require too many ad-hoc techniques as well as cumbersome and time-consuming programming. Our System on Mobile Devices (SyD) middleware, on the other hand, has a modular architecture that makes such application development very systematic and streamlined. The architecture supports transactions over mobile data stores, with a range of remote group invocation options and embedded interdependencies among such data store objects. The architecture further provides a persistent uniform object view, group transaction with Quality of Service (QoS) specifications, and XML vocabulary for inter-device communication. This paper presents the basic SyD concepts, introduces the architecture and the design of the SyD middleware and its components. We also provide guidelines for SyD application development and the deployment process. We include the basic performance figures of SyD components and a few SyD applications on Personal Digital Assistant (PDA). We believe that SyD is the first comprehensive working prototype of its kind, with a small code footprint of 112 KB with 76 KB being device-resident, and it has a good potential for incorporating many ideas for performance extensions, scalability, QoS, workflows and security.