In distributed applications, several processes are involved in serving a request. The state of the request is encoded in the states of their processes. This can lead to unnecessary complexity and hard-to-detect errors. This paper presents an architectural style, token architectures, that decouples data, control and synchronization. Tokens encapsulate the state of a computation. Service points manipulate the tokens and perform services for them. The tokens use maps to move between service stations. We show in an example how this style simplifies the design of a telecommunications application and what difficulties traditional designs must solve.

The main problem in developing software product families is how to share effort and reuse parts of design and implementation while providing variation of features and capabilities in the products.We discuss the mechanisms that are commonly used to achieve reuse and sharing in product families, and the kind of variance each is best suited for.Our analysis motivates a need for a new mechanism to deal with ad hoc variation of features found in different members of a family.We argue that higher level abstraction and parametrization techniques are not well suited for this task.We propose an alternative approach that enables sufficiently detailed designs for every variant and at the same time achieves a level of design reuse without making designs unnecessarily complex or implementations inefficient.