E. Badescu

Online software for the ATLAS test beam data acquisition system

The Online Software is the global system software of the ATLAS data acquisition (DAQ) system, responsible for the configuration, control and information sharing of the ATLAS DAQ System. A test beam facility offers the ATLAS detectors the possibility to study important performance aspects as well as to proceed on the way to the final ATLAS DAQ system. Last year, three subdetectors of ATLAS-separately and combined-were successfully using the Online Software for the control of their datataking. In this paper, we describe the different components of the Online Software together with their usage at the ATLAS test beam.

Use of CORBA in the ATLAS prototype DAQ

This paper presents the experience of using a CORBA-based communication package for inter-component communication of control and status information in the ATLAS prototype DAQ project. A public domain package, called Inter-Language Unification (ILU) has been used to implement CORBA-based communication between DAQ components in a local area network (LAN) of heterogeneous computers. The selection of the CORBA standard and the ILU implementation are judged against the requirements of the DAQ system. An overview of ILU is included. Several components of the DAQ system have been designed and implemented using CORBA/ILU for which the development procedure and environment are described.

CONTROL IN THE ATLAS TDAQ SYSTEM

The unprecedented size and complexity of the ATLAS TDAQ system requires a comprehensive and flexible control system. Its role ranges from the so-called run- control, e.g. starting and stopping the data taking, to error handling and fault tolerance. It also includes initialization and verification of the overall system. Following the traditional approach a hierarchical system of customizable controllers has been proposed. For the final system all functionality will be therefore available in a distributed manner, with the possibility of local customization. After a technology survey the open source expert system CLIPS has been chosen as a basis for the implementation of the supervision and the verification system. The CLIPS interpreter has been extended to provide a general control framework. Other ATLAS Online software components have been integrated as plug-ins and provide the mechanism for configuration and communication. Several components have been implemented sharing this technology. The dynamic behavior of the individual component is fully described by the rules, while the framework is based on a common implementation. During this year these components have been the subject of scalability tests up to the full system size. Encouraging results are presented and validate the technology choice.

Deployment and use of the ATLAS DAQ in the combined test beam

The ATLAS collaboration at CERN operated a combined test beam (CTB) from May until November 2004. The prototype of ATLAS data acquisition system (DAQ) was used to integrate other subsystems into a common CTB setup. Data were collected synchronously from all the ATLAS detectors, which represented nine different detector technologies. Electronics and software of the first level trigger were used to trigger the setup. Event selection algorithms of the high level trigger were integrated with the system and were tested with real detector data. A possibility to operate a remote event filter farm synchronized with ATLAS TDAQ was also tested. Event data, as well as detectors conditions data were made available for offline analysis

Performance and scalability of the back-end sub-system in the ATLAS DAQ/EF prototype

The DAQ group of the future ATLAS experiment has developed a prototype system based on the Trigger/DAQ architecture described in the ATLAS Technical Proposal to support studies of the full system functionality, architecture as well as available hardware and software technologies. One sub-system of this prototype is the back-end which encompasses the software needed to configure, control and monitor the DAQ, but excludes the processing and transportation of physics data. The back-end consists of a number of components including run control, configuration databases and message reporting system. The software has been developed using standard, external software technologies such as OO databases and CORBA. It has been ported to several C++ compilers and operating systems including Solaris, Linux, WNT and LynxOS. This paper gives an overview of the back-end software, its performance, scalability and current status.