SCXML on Resource Constrained Devices

Abstract

Ever since their introduction as a visual formalism by Harel et al. in 1987, state-charts played an important role to formally specify the behavior of reactive systems. However, various shortcomings in their original formalization lead to a plethora of formal semantics for their interpretation in the subsequent years. In 2005, the W3C Voice Browser Working Group started an attempt to specify SCXML as an XML dialect and corresponding semantic for state-charts and their interpretation, promoted to W3C recommendation status in 2015. In the context of multimodal interaction, SCXML derives a special relevance as the markup language proposed to express dialog models as descriptions of interaction in the multimodal dialog system specified by the W3C Multimodal Interaction Working Group. However, corresponding SCXML interpreters are oftentimes embedded in elaborate host environments, are very simplified or require significant resources when interpreted. In this chapter, we present a more compact, equivalent representation for SCXML documents as native data structures with a respective syntactical transformation and their interpretation by an implementation in ANSI C. We discuss the characteristics of the approach in terms of binary size, memory requirements, and processing speed. This will, ultimately, enable us to gain the insights to transform SCXML state-charts for embedded systems with very limited processing capabilities and even integrated circuits.