Short time-to-market is an important requirement for developing web-based systems. Software architecture plays a critical role for time-to-market objective to be satisfied since it forms a blueprint for the system structure, indicating the principle loci of later activities such as detailed design and implementation. In particular, we need a novel way for system decomposition to achieve reduced complexity, encapsulated change, and maximized reuse possibility. In this paper we address these problems by separation of concerns, applying patterns, and forming components. We firstly present a component-based reference model for web-based systems. The main interest here is to capture early design decisions associated with short time-to-market concern and provide guidelines for system decomposition and architecture construction. We then discuss issues concerning component development within the reference model. Three component patterns are identified to achieve flexible and efficient reuse. ...