Increasingly, complex software systems are being constructed as
compositions of reusable software components. One critical issue for
such constructions is the design and implementation of the interaction
mechanisms, or connectors, that permit the various software components
to work together properly. Complex systems also often have
extra-functional requirements which these connectors must satisfy.

It is not always possible to find an existing connector that satisfies
the requirements of the system, and at present it is time-consuming
and difficult to create new kinds of connectors.  A principled,
compositional means of systematically constructing connectors is
needed.

In this thesis I describe a new approach in which a basic connector
type (such as RPC or data streams) can be augmented with selected
adaptations or enhancements to produce a more complex connector type.
I characterize a small set of structural transformations that can be
applied compositionally to basic connector types to arrive at a wide
variety of useful complex connector types.  I give formal semantics
for these transformations and demonstrate that it is possible to
semi-automatically generate implementations of instances of the new
connector types.  I explore and evaluate this idea in the context of
dependability, using transformations to increase the reliability of
existing component interaction mechanisms.