The Abstract Task Graph: A Methodology for Architecture-Independent Programming of Networked Sensor Systems

The Abstract Task Graph (ATaG) is a data driven programming model for end-to-end application development on networked sensor systems. An ATaG program is a system-level, architecture-independent specification of the application functionality. The application is modeled as a set of abstract tasks that represent types of information processing functions in the system, and a set of abstract data items that represent types of information exchanged between abstract tasks. Input and output relationships between abstract tasks and data items are explicitly indicated as channels. Each abstract task is associated with user-provided code that implements the actual information processing functions in the system. Appropriate numbers and types of tasks can then be instantiated at compile-time or run-time to match the actual hardware and network configuration, with each node incorporating the user-provided code, automatically generated glue code, and a runtime engine that manages all coordination and communication in the network. This paper primarily deals with the key concepts of ATaG and the program syntax and semantics. The end-to-end application development methodology is discussed briefly.