One important facet of software reuse is the reuse of autonomous 
and distributed computational services. Components or applications 
offering services stay at the provider's site, where they are developed, 
kept securely, operated, maintained, and updated. Instead of purchasing 
software components, the customer buys services by invoking methods 
provided by these remote applications over the Internet. Due to the 
autonomy of the services, this reuse model causes specific requirements 
that differ from those where one builds one's own system from components.
These requirements have led to the definition of CPAM, a protocol for 
reusing remote and autonomous services. CPAM can be used on top of 
various distribution systems, and offers features like presetting of 
attributes, run-time estimation of costs and having several calls for 
setup, invocation and result extraction. The CPAM protocol has been 
successfully used within CHAIMS, a reuse environment that supports 
the generation of client applications based on CPAM.