This paper presents modeling concern to construct context data format that is applicable for context-aware computing. The first concern deals with developing abstract model at application entity which is defined independently from presentation entity. Regarding to this matter, the context data format have been constructed as higher and lower abstraction model presented in OWL and XML instance. The second concern deals with mapping lower abstraction model to exchange format. JSON exchange format is proposed in this paper as the alternative to the incumbent XML. The context data format, which is constructed at lower abstraction model, has been transformed to JSON by applying XSLT rule. As a result, JSON exchange format is obviously smaller than XML in term of exchange format size. ©2007 IEEE.