The tension between software architecture and agility is not well understood by agile practitioners or researchers. If an agile software team spends too little time designing architecture up-front then the team faces increased risk and higher chance of failure, if the team spends too much time the delivery of value to the customer is delayed, and responding to change can become extremely difficult. This paper presents a grounded theory of agile architecture that describes how agile software teams answer the question of how much upfront architecture design effort is enough. This theory, based on grounded theory research involving 44 participants, presents six forces that affect the team's context and five strategies that teams use to help them determine how much effort they should put into up-front design.

Existing nuclear power generation facilities are currently seeking to replace obsolete analog Instrumentation and Control (I&C) systems with contemporary digital and processor based systems. However, as new technology is introduced into existing and new plants, it becomes vital to assess the impact of that technology on plant safety. From a regulatory point of view, the introduction or consideration of new digital I&C systems into nuclear power plants raises concerns regarding the possibility that the fielding of these I&C systems may introduce unknown or unanticipated failure modes. In this paper, we present a fault injection based safety assessment methodology that was applied to a commercial safety grade digital Reactor Protection System. Approximately 10,000 fault injections were applied to the system. This paper presents a overview of the research effort, lessons learned, and the results of the endeavor.