Due to unique characteristics of datacenter applications, such as high volume and dynamic traffic patterns of short flows, micro-bursts significantly impact the application performance. Moreover, the reactive nature of congestion control (CC) algorithms makes CC ineffective against micro-bursts. This paper introduces the Notification of Change Events (NCE) mechanism. Compared to the Explicit Congestion Notification (ECN) schemes, where switches send information to hosts, NCE uses a dual approach that sends information from "transport layer" of sources to the network. This design provides a proactive in-network solution that mitigates micro-bursts in real-time with the help of the information from the application. Simulation results demonstrate NCE can improve the flow completion time of short flows up to 62% with negligible impacts on long flow throughput.