The software architecture of a system has influences against various software characteristics of the system such as efficiency, reliability, maintainability, and etc.. For supporting to design the software architecture, we have developed architectural styles for distributed processing systems. The styles classify the architecture for distributed processing systems into nine categories based on the location of data storage and the type of processing between a client and a server. This paper describes our architectural styles and proposes a simple but practical method to select an appropriate architectural style for developing an application system. The selection method introduces the characterization of architectural styles and the characteristic charts to visualize their characteristics of architectural styles. Next, we propose a method to select an appropriate architectural style using the conformity between characteristic charts of a system and architectural styles. We have verified...