This document describes techniques to display presence indicators in real-time chat applications. The techniques enable accurate presence indicators with low overheads. A server compares successive timestamps to determine whether a time threshold is met. If the time threshold is met, the server pushes an updated last-seen timestamp to clients. Otherwise, the server only selectively pushes the updated last-seen timestamp to clients. The client polls the server if the last-seen timestamp meets a threshold difference from the current time. The combination of pushing by a server and polling by a client to selectively update last-seen timestamps enables accurate and consistent representation of presence state for multiple users and client devices. The techniques save server resources, network costs, and reduce energy demands on client devices.
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Wikström, Johan, "PRESENCE INDICATION IN REAL-TIME CHAT APPLICATIONS", Technical Disclosure Commons, (March 24, 2016)