ABSTRACT:
A holy grail of component-based software engineering is "write-once, reuse
everywhere".  However, in modern distributed, component-based systems
supporting emerging application areas such as service-oriented e-business,
this is difficult.  Non-functional requirements (related to
quality-of-service (QoS) issues such as security, reliability, and
performance) vary with deployment context, and sometimes even at
run-time, complicating the task of re-using components.
                                                                                
I will present a middleware-based approach to managing changing requirements
of components.  Functional component interfaces are decorated with links to
independently evolvable, declarative assertions (policies) that advertise
non-functional capabilities.  Middleware enhancements match, interpret,
and mediate requirements of clients and servers at deployment time and/or
runtime.  A programming model for extending existing applications with
components to implement new application level protocols or features will
also be presented.  This approach offers the software engineer a flexible
solution to handle changing QoS requirements in a well-structured manner.