A Quality- and Cost-based Selection Model for Multimedia Service Composition in Mobile Environments

When moving from monolithic applications towards service-oriented multimedia frameworks, the composition of Web services to form complex multimedia workflows becomes a demanding problem. Especially mobile devices require a flexible composition strategy as they often have to move computationally complex or power-demanding tasks to powerful servers. Such a strategy also has to consider the changing environment due to movements of the device and it has to adapt to device-specific characteristics, e.g., the current battery level. Hence, mobile devices experience problems beyond the mere question of services´ availability or successful execution. We propose the E²Mon algorithm that monitors the execution chain of Web services and gracefully recovers from failures of individual services and network-specific or device-specific alarms. The sophisticated control flow dynamically chooses the quality-optimal and cost-optimal composition of available services handling both successive and parallel service execution