Support for flexibility and variability is a key quality attribute of many software architectures, especially of platform and product line architectures, which form the architectural basis for many different software systems or products.

Designing flexible software architectures is a challenge, however. Too little support for flexibility means not meeting all varaibility requirements. Too much flexibility, in contrast, often results in software architectures that are so flexible that it is difficult or even impossible to create a meaningful instance of that architecture. Flexibility in the wrong place or realized with inappropriate design measures can even result in unusable or even inflexible software architecture. And often, flexibility requirements are in conflict with other architecture qualities, such as performance and robustness.

This talk, therefore, explores common patterns and practices that help desinging software architectures that exhibiit the right degree of flexibility: nott to litte, not too much, and always with appropriate measures. In addition, the talk hints at technologies that can help realizing the chosen flexibility design tactics.