1. A computer-implemented method of realtime data stream handling in a network communication environment comprising a network service implemented by at least one server network node and supporting realtime communications between respective network nodes of a user and other communicants associated with respective communicant objects in one or more virtual areas, comprising by the user's network node: parsing a specification of a realtime stream handler from one or more stream handling instructions received from the network service in connection with a particular one of the one or more virtual areas, wherein the parsing comprises parsing an input source identifier, an output sink identifier, and a respective identifier of each of one or more data processing objects from the one or more stream handing instructions, wherein the one or more stream handling instructions are based on realtime position information describing respective positions of respective ones of the communicant objects in the particular virtual area; instantiating realtime stream handling objects corresponding to the parsed identifiers; creating a directed graph from the instantiated realtime stream handling objects in accordance with the specification; receiving a realtime data stream from an input source corresponding to the input source identifier; and producing a resultant data stream at an output sink corresponding to the output sink identifier, wherein the producing comprises processing the realtime data stream through the directed graph, wherein the producing is based on configuration parameter values determined from the realtime position information and comprises dynamically configuring one or more of the instantiated realtime stream handling objects in the directed graph with the configuration parameter values.