Asynchronous Distributed Object Model Using Java for the Control System of a Synchrotron Radiation Source

A simple distributed object model, called an asynchronous distributed object protocol (ADOP), was designed and implemented as middleware for a control system of a synchrotron radiation source. The ADOP replaces time-constrained parts of the control system that were previously based on the Java Remote Method Invocation (RMI) model. Under RMI’s synchronous communication, when a client executes a remote-method invocation for a device/component to be controlled on a remote server, the client is suspended until the server sends a result back to the client after completing the control sequence. Using the ADOP, even in a multi-client environment, clients are not blocked when they make remote-method invocations with an object parameter/return object that includes short control data associated with the event data, status data, and setting data for the devices/components. The clients can asynchronously receive resultant control data from the remote servers. Performance measurements obtained in experiments demonstrate that the ADOP had an execution time that was 1.4–13.1% of the RMI’s execution time.