[ACM Press the joint ACM SIGSOFT conference -- QoSA and ACM SIGSOFT symposium -- ISARCS - Boulder, Colorado, USA (2011.06.20-2011.06.24)] Proceedings of the joint ACM SIGSOFT conference -- QoSA and ACM SIGSOFT symposium -- ISARCS on Quality of software architectures -- QoSA and architecting critical systems -- ISARCS - QoSA-ISARCS '11 - Towards a process for architectural modelling in agile software development