Response Time Aware Operator Placement for Complex Event Processing in Edge Computing.

A typical complex event processing (CEP) service is composed by a set of operators organized as a directed acyclic graph. This kind of service is usually used to handle large amounts of real-time data. Meanwhile, edge computing has been widely accepted as a new paradigm to improve the QoS of deployed services by making the services closer to the data. Thus, the response time, which is a crucial QoS metric for CEP services, can be significantly reduced by deploying CEP services on the edge network. However, it is often unlikely for a single node of the edge network to host all operators of a CEP service due to the limited computing resources. Therefore, it is desirable for a CEP service to place its operators on different nodes of the edge network to keep the response time low, especially when the input rate of the CEP service significantly increases. In this paper, we reduce the average response time of CEP services by deploying the operators on the edge nodes dynamically according to the predicted response time of CEP services. Specifically, we first propose a system model to capture the response time of the CEP services, based on which we formulate the problem of the optimal placement of CEP operators in the edge network. We then propose an algorithm that predicts the response time of CEP services and deploys the operators on the edge nodes with the minimum predicted delay. A simulation-based evaluation demonstrates that, compared with two state-of-the art algorithms, our algorithm can reduce the total response time by 33(%) and 45(%) on average, respectively.