Abstract. Many modern distributed software applications require a continuous interaction between their components exploiting streaming data from the server to the client. The Abstract Behavioral Specification (ABS) language has been developed for the modeling and analysis of distributed systems. In ABS, concurrent objects communicate by calling each other's methods asynchronously. Return values are communicated asynchronously too via the return statement and so-called futures. In this paper, we extend the basic ABS model of asynchronous method invocation and return in order to support the streaming of data. We introduce the notion of a "Future-based Data Stream" to extend the ABS. The application of this notion and its impact on performance are illustrated by means of a case study in the domain of social networks simulation.