The WWW has made information and services more available than ever before. Many of the first Web applications have been emulations of real world activities, in particular, e-commerce. But so far, the use of information and services on the Web has been a solitary one. We propose a component-based architecture for collaboration that provides shared navigation of the WWW along with an EJB-based server implementation. As a particular application built on this architecture, we present MultECommerce, through which multiple users can participate in virtual shopping trips among multiple shopping sites. MultECommerce features a multi-site shopping cart and enables one-stop checkout from all visited shopping sites. We examine security and performance issues of our architecture. Categories and Subject Descriptors D.2.11 [Software Engineering]: Software Architectures – Domain-specific architectures, Patterns General Terms Design, Performance, Experimentation, Human Factors Keywords E-commerce a...