1. A battery-powered client computing device comprising: a battery configured to power the client computing device; a wireless communication interface configured to establish a wireless communication channel with a host computing device; a logic machine; and a storage machine holding instructions executable by the logic machine to: communicate, via the wireless communication interface, with the host computing device using a host-mediated transport layer protocol in which only the host computing device initiates communication between the battery-powered client computing device and the host computing device; establish a plurality of subscriptions to receive data published by a plurality of data sources of the battery-powered client computing device, each subscription corresponding to a different data source; in response to receiving published data from any data source of the battery-powered client computing device via a subscription, store the published data in a subscription buffer; and in response to receiving, from a remote subscription dispatcher of the host computing device via the host-mediated transport layer protocol, a read request for data published by data sources of the battery-powered client computing device in accordance with the plurality of subscriptions, send, via the wireless communication interface, to the host computing device one or more data packets including published data stored in the subscription buffer.