The design of naming-based service composition system for ubiquitous computing applications

In the future, huge amount of embedded and invisible devices as well as software components are connected to the Internet, and these ´functional objects´ are expected to play an important role to provide convenience services to users. In such ubiquitous computing environment, users utilize various applications through functional objects anytime and anywhere. Since ubiquitous computing environment are highly dynamic, heterogeneous, and context-dependent environment, application should change their functionality depending on dynamically changing user´s context. For example, when a user wishes to brows a PDF file on his small PDA display, document browsing application running on the PDA needs some kind of additional transcoder function to reformat the PDF file. If the user wish to use voice-only device (e.g. PDC) to obtain some information in the PDF document, the application need to locate and use PDF-to-text function as well as text-to-voice function. Thus, to enable ubiquitous computing applications to change their functionality on the fly, a mechanism capable of locating appropriate functions transparently on the Internet is necessary. Generally, such kind of locating mechanism can be supported by location-independent naming system. However, the name space of such naming system tends to be flat, designing scalable naming system is quite challenging. This paper describes the design of a new scalable location-independent naming system called interface-based naming system (IFNS) which has capable of locating functional objects transparently in ubiquitous computing environment. In the design of IFNS, we utilize interface information to name functional object. As shown in this paper, interface information enables us to design scalable name management and name resolution algorithm in a fully distributed manner. In addition, interface information not only enables transparent location of functional objects, but also enables naming system to support automatic function syntheses. Simulations results show that the proposed IFNS has acceptable scalability and performance to utilize functional objects in ubiquitous computing environment.