In traditional web application development, very few libraries exist to make portal development easy. In general, many homegrown and vertical solutions exist and very little code is shared or reused. Finally with the emergence of some critical new web technologies, web application development is focusing more on reusable solutions and software. The GridSphere portal framework provides a standards based portal for the easy development of modular web components, called portlets. Portlets are defined by a standard API and provide a model for developing new portal components that can be shared and exchanged by various portlet containers. GridSphere provides both a portlet container, a collection of core portlets and an advanced user interface library that makes developing new portlets easier for application developers. This paper discusses briefly the the GridSphere portal architecture including the layout engine, support for two portlet API implementations and the portlet services model....