The creation of composite services from service components at runtime can be achieved using several different techniques. In the first approach, a new common interface is constructed at runtime which allows the functionality of two or more components to be accessed from a single entity while the service components themselves remain distinct and potentially distributed within in a network. In the second approach, a new composite service is formed where all of the functionality of the service components is housed within a single new service. In the third approach, a new composite service is formed where all the functionality of the service components is extracted and re-assembled into the body of a single new service. This paper describes the design of an infrastructure to support the runtime creation of composite services. An application to create user-defined security associations dynamically and deploy them between any two points in the Internet is presented to exemplify the need for dynamic service composition techniques. Some other potential applications in e-commerce and software provisioning are also discussed.