Date Added: May 2011
When planning Service-Oriented Architectures requirements declared in Service Level Agreements (SLAs) have to be considered. SLAs cover functional as well as quantitative requirements like load levels, services rates and delay times. As external factors can influence distributed systems, SLAs have to include tolerances for quantitative requirements. Early design phases of SOA use analytic models to check functional properties. However, formalization of quantitative requirements in SLAs and their validation in analytic models is still a field of research. A challenge is the description of soft deadlines and the way delay times grow under different load levels.