Component-Based Development(CBD) leverages software reusability and diminishes development costs. Various works about component models, such as EJB, COM, and CCM are in progress to support CBD. However, current component models hardly support flexible assembly of pre-built components. To cope with this problem, architecture for component assembly must be defined in the abstract level and the gap between system architecture and its implementation should be diminished in the implementation level. This paper proposes a method for architecture-based design and implementation of component assembly. Architecture is described by the ADL, and the tool, COBALT Assembler, is introduced to support the proposed design and implementation phase of component assembly.