Based upon local libraries, component technology has achieved higher degrees of flexibility, customizability and reusability. However, it has little or no support for extensibility and evolvability. Web-based technologies make possible new classes of software systems supporting efficient, timely delivery of content to interested parties, and corresponding component models ought to support a more powerful and useful approach based upon distributed component libraries, radically changing the deployment and maintainability of component-based software systems.This paper introduces a metacomponent model that supports on demand, dynamic distribution and integration of distributed, versioned, reusable software artifacts on user environments during runtime. The model combines hypertext-based Web concepts and mobile code abstractions to define a transparent, distributed component library for deploying and updating components required by software systems, ensuring the quality of delivered applications throughout their entire lifecycle. What makes this approach unique is its support for extensibility and evolvability triggered by changing user needs.