Applications in cyber-physical systems are increasingly coupled with online instruments to perform long running, continuous data processing. Such "always on" dataflow applications are dynamic, where they need to change the applications logic and performance at runtime, in response to external operational needs. Floe is a continuous dataflow framework that is designed to be adaptive for dynamic applications on Cloud infrastructure. It offers advanced dataflow patterns like BSP and MapReduce for flexible and holistic composition of streams and files, and supports dynamic recomposition at runtime with minimal impact on the execution. Adaptive resource allocation strategies allow our framework to effectively use elastic Cloud resources to meet varying data rates. We illustrate the design patterns of Floe by running an integration pipeline and a tweet clustering application from the Smart Power Grids domain on a private Eucalyptus Cloud. The responsiveness of our resource adaptation is validated through simulations for periodic, bursty and random workloads.
Application dynamism have be explored using concepts such as frames, templates and dynamic embedding @cite_15 . However, these are in the context of scientific workflows where the choice for the dynamic task is finalized before the execution of that task begins which is in contrast to the requirement in the continuous dataflows where an executing task needs to be seamlessly updated at runtime as is support by .
@cite_15
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While most scientific workflows systems are based on dataflow, some amount of control-flow modeling is often necessary for engineering fault-tolerant, robust, and adaptive workflows. However, control-flow modeling within dataflow often results in workflow specifications that are hard to comprehend, reuse, and maintain. We describe new modeling constructs to address these issues that provide a structured approach for modeling control-flow within scientific workflows, and discuss their implementation within the Kepler scientific workflow system.