´Timed atomic write´: a programming primitive for distributed embedded systems

In a distributed embedded system, one or more data items may be moved from one functional module to another through a common buffer that is interposed between them over a network. Here, the computation modules generating and/or disseminating data should agree on what data items are written into the remote buffer, to coordinate their actions on the external environment. Furthermore, a timely effect of these actions requires enforcing deadlines on the processing of data from the remote buffer. We encouch the functionalities of reaching agreement on the data processed through a shared buffer and meeting the time deadlines associated with this data in an abstract programming primitive: ´timed atomic write´. The primitive has a rich semantics in that it enables a consistent view of the processing on data in the buffer by various computation modules over prescribed time intervals. The primitive allows an explicit application-level control of the asynchrony and timing of information flow between various modules. The paper describes the structure and semantics of the ´atomic write´ primitive, and illustrates its use in a ´sensor data fusion´ application.