Remote control of data acquisition devices by means of message oriented middleware

The TJ-II autonomous acquisition systems are computers running dedicated applications for programming and controlling data acquisition channels and also integrating acquired data into the central database. These computers are located in the experimental hall and have to be remotely controlled during plasma discharges. A remote control for these systems has been implemented by taking advantage of the message-oriented middleware recently introduced into the TJ-II data acquisition system. Java Message Service (JMS) is used as the messaging application program interface. All the acquisition actions that are available through the system console of the data acquisition computers (starting or aborting an acquisition, restarting the system or updating the acquisition application) can now be initiated remotely. Command messages are sent to the acquisition systems located in the experimental hall close to the TJ-II device by using the messaging software, without having to use a remote desktop application that produces heavy network traffic and requires manual operation. Action commands can be sent to only one or to several/many acquisition systems at the same time. This software is integrated into the TJ-II remote participation system and the acquisition systems can be commanded from inside or outside the laboratory. All this software is integrated into the security framework provided by PAPI, thus preventing non-authorized users commanding the acquisition computers. In order to dimension and distribute messaging services some performance tests of the message oriented middleware software have been carried out. Results of the tests are presented. As suggested by the tests results different transport connectors are used: TCP transport protocol is used for the local environment, while HTTP protocol is used for remote accesses, thereby allowing the system performance to be optimized.