Grid and service computing technologies have been explored by enterprises to promote integration, sharing, and collaboration. However, quick response to business environment changes is still a challenging issue. For end users, developing, customizing, and reengineering applications remain a difficult and timeconsuming task. Users still need to deal with excessive low-level details of platform-specific APIs. We present a high-level programming model together with a descriptive glueing language called GSML, to facilitate end-user programming. In this approach, applications could be visually composed from welldefined software components called "funnels" in an event-driven fashion. Application examples have shown that, by raising the level of abstraction as well as simplifying the programming model, GSML could empower end users to build grid applications on demand with improved productivity.