We take a process component as a pair of an interface and a behaviour. We
study the composition of interacting process components in the setting of
process algebra. We formalize the interfaces of interacting process components
by means of an interface group. An interesting feature of the interface group
is that it allows for distinguishing between expectations and promises in
interfaces of process components. This distinction comes into play in case
components with both client and server behaviour are involved.Comment: 26 pages; section on non-associativity of component composition
added, examples adde