This paper presents a formal model of concurrent system that is equipped with the capabilities of higher-order communication. That is a translation of the asynchronous higher order π-calculus into a graph rewriting model. A new operation, code streaming is introduced. Code streaming is performed by the pair of a stream and an input process. An input process consists of an input stream and behaviours. It can perform the receiving of a higher-order structure and the execution of the behaviours in parallel. The input process can execute a fragment of the received code before the transfer completes. The calculus models computations transferring mobile codes and links on a wide-area network in asynchronous manner. A set of reaction rules is presented for the operational semantics.