A stream transport protocol supports realtime network communications between communicants operating on respective network nodes. The stream transport protocol supports remote management of client communication sessions, including provisioning of each pair of client network nodes with a respective session definition defining a respective peer-to-peer session over a network connection between the constituent client network nodes of the pair. The stream transport protocol has relatively low computational resource requirements so that realtime communications performance can be achieved using a wide range of computing devices and network connections that currently are available.