One of the STAR experiment's modular Messaging Interface and Reliable Architecture framework (MIRA) integration goals is to provide seamless and automatic connections with the existing control ...systems. After an initial proof of concept and operation of the MIRA system as a parallel data collection system for online use and real-time monitoring, the STAR Software and Computing group is now working on the integration of Experimental Physics and Industrial Control System (EPICS) with MIRA's interfaces. This integration goals are to allow functional interoperability and, later on, to replace the existing/legacy Detector Control System components at the service level. In this report, we describe the evolutionary integration process and, as an example, will discuss the EPICS Alarm Handler conversion. We review the complete upgrade procedure starting with the integration of EPICS-originated alarm signals propagation into MIRA, followed by the replacement of the existing operator interface based on Motif Editor and Display Manager (MEDM) with modern portable web-based Alarm Handler interface. To achieve this aim, we have built an EPICS-to-MQTT 8 bridging service, and recreated the functionality of the original Alarm Handler using low-latency web messaging technologies. The integration of EPICS alarm handling into our messaging framework allowed STAR to improve the DCS alarm awareness of existing STAR DAQ and RTS services, which use MIRA as a primary source of experiment control information.
User Centric Monitoring (or UCM) has been a long awaited feature in STAR, whereas programs, workflows and system "events" could be logged, broadcast and later analyzed. UCM allows to collect and ...filter available job monitoring information from various resources and present it to users in a user-centric view rather than an administrative-centric point of view. The first attempt and implementation of "a" UCM approach was made in STAR 2004 using a log4cxx plug-in back-end and then further evolved with an attempt to push toward a scalable database back-end (2006) and finally using a Web-Service approach (2010, CSW4DB SBIR). The latest showed to be incomplete and not addressing the evolving needs of the experiment where streamlined messages for online (data acquisition) purposes as well as the continuous support for the data mining needs and event analysis need to coexists and unified in a seamless approach. The code also revealed to be hardly maintainable. This paper presents the next evolutionary step of the UCM toolkit, a redesign and redirection of our latest attempt acknowledging and integrating recent technologies and a simpler, maintainable and yet scalable manner. The extended version of the job logging package is built upon three-tier approach based on Task, Job and Event, and features a Web-Service based logging API, a responsive AJAX-powered user interface, and a database back-end relying on MongoDB, which is uniquely suited for STAR needs. In addition, we present details of integration of this logging package with the STAR offline and online software frameworks. Leveraging on the reported experience and work from the ATLAS and CMS experience on using the ESPER engine, we discuss and show how such approach has been implemented in STAR for meta-data event triggering stream processing and filtering. An ESPER based solution seems to fit well into the online data acquisition system where many systems are monitored.
In preparation for the new era of RHIC running (RHIC-II upgrades and possibly, the eRHIC era), the STAR experiment is expanding its modular Message Interface and Reliable Architecture framework ...(MIRA). MIRA allowed STAR to integrate meta-data collection, monitoring, and online QA components in a very agile and efficient manner using a messaging infrastructure approach. In this paper, we briefly summarize our past achievements, provide an overview of the recent development activities focused on messaging patterns and describe our experience with the complex event processor (CEP) recently integrated into the MIRA framework. CEP was used in the recent RHIC Run 14, which provided practical use cases. Finally, we present our requirements and expectations for the planned expansion of our systems, which will allow our framework to acquire features typically associated with Detector Control Systems. Special attention is given to aspects related to latency, scalability and interoperability within heterogeneous set of services, various data and meta-data acquisition components coexisting in STAR online domain.
STAR collaboration's record system is a collection of heterogeneous and sparse information associated to each members and institutions. In its original incarnation, only flat information was stored ...revealing many restrictions such as the lack of historical change information, the inability to keep track of members leaving and re-joining STAR, or the ability to easily extend the saved information as new requirements appeared. In mid-2013, a new project was launched covering an extensive set of revisited requirements. The requirements led us to a design based on a RESTful API, back-end storage engine relying on key/value pair data representation model coupled with a tiered architecture design. This design was motivated by the fact that unifying many STAR tools, relying on the same business logic and storage engine, was a key and central feature for the maintainability and presentation of records. This central service API would leave no ambiguities and provide easy service integration between STAR tools. The new design stores the changes in records dynamically and allows tracking the changes chronologically. The storage engine is extensible as new field of information emerges (member specific or general) without affecting the presentation or the business logic layers. The new record system features a convenient administrative interface, fuzzy algorithms for data entry and search, and provides basic statistics and graphs. Finally, this modular approach is supplemented with access control, allowing private information and administrative operations to be hidden away from public eyes.
We report our experience on migrating STARs Online Services (Run Control System, Data Acquisition System, Slow Control System and Subsystem Monitoring) from direct read/write database accesses to a ...modern non-blocking message-oriented infrastructure. Based on the Advanced Messaging Queuing Protocol (AMQP) and standards, this novel approach does not specify the message data structure, allowing great flexibility in its use. After careful consideration, we chose Google Protocol Buffers as our primary (de)serialization format for structured data exchange. This migration allows us to reduce the overall system complexity and greatly improve the reliability of the metadata collection and the performance of our online services in general. We will present this new framework through its software architecture overview, providing details about our staged and non-disruptive migration process as well as details of the implementation of pluggable components to provide future improvements without compromising stability and availability of services.
The STAR Experiment further exploits scalable message-oriented model principles to achieve a high level of control over online data streams. In this paper we present an AMQP-powered Message Interface ...and Reliable Architecture framework (MIRA), which allows STAR to orchestrate the activities of Meta-data Collection, Monitoring, Online QA and several Run-Time and Data Acquisition system components in a very efficient manner. The very nature of the reliable message bus suggests parallel usage of multiple independent storage mechanisms for our meta-data. We describe our experience with a robust data-taking setup employing MySQL- and HyperTable-based archivers for meta-data processing. In addition, MIRA has an AJAX-enabled web GUI, which allows real-time visualisation of online process flow and detector subsystem states, and doubles as a sophisticated alarm system when combined with complex event processing engines like Esper, Borealis or Cayuga. The performance data and our planned path forward are based on our experience during the 2011-2012 running of STAR.
In recent years, the STAR experiment's database demands have grown in accord not only with simple facility growth, but also with a growing physics program. In addition to the accumulated metadata ...from a decade of operations, refinements to detector calibrations force user analysis to access database information post data production. Users may access any year's data at any point in time, causing a near random access of the metadata queried, contrary to time-organized production cycles. Moreover, complex online event selection algorithms created a query scarcity ("sparsity") scenario for offline production further impacting performance. Fundamental changes in our hardware approach were hence necessary to improve query speed. Initial strategic improvements were focused on developing fault-tolerant, load-balanced access to a multi-slave infrastructure. Beyond that, we explored, tested and quantified the benefits of introducing a Tiered storage architecture composed of conventional drives, solid-state disks, and memory-resident databases as well as leveraging the use of smaller database services fitting in memory. The results of our extensive testing in real life usage are presented.
Cyber security requirements for secure access to computing facilities often call for access controls via gatekeepers and the use of two-factor authentication. Using SSH keys to satisfy the two factor ...authentication requirement has introduced a potentially challenging task of managing the keys and their associations with individual users and user accounts. Approaches for a facility with the simple model of one remote user corresponding to one local user would not work at facilities that require a many-to-many mapping between users and accounts on multiple systems. We will present an SSH key management system we developed, tested and deployed to address the many-to-many dilemma in the environment of the STAR experiment. We will explain its use in an online computing context and explain how it makes possible the management and tracing of group account access spread over many sub-system components (data acquisition, slow controls, trigger, detector instrumentation, etc.) without the use of shared passwords for remote logins.
We present the measurement of the transverse single-spin asymmetry of weak boson production in transversely polarized proton-proton collisions at s radical =500GeV by the STAR experiment at RHIC. The ...measured observable is sensitive to the Sivers function, one of the transverse-momentum-dependent parton distribution functions, which is predicted to have the opposite sign in proton-proton collisions from that observed in deep inelastic lepton-proton scattering. These data provide the first experimental investigation of the nonuniversality of the Sivers function, fundamental to our understanding of QCD.
We present high precision measurements of elliptic flow near midrapidity (y<1.0 ) for multistrange hadrons and varphi meson as a function of centrality and transverse momentum in Au+Au collisions at ...center of mass energy s NN - - - - radical =200GeV . We observe that the transverse momentum dependence of varphi and Omega v 2 is similar to that of pi and p , respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0%-30% and 30%-80% collision centrality. There is an indication of the breakdown of previously observed mass ordering between varphi and proton v 2 at low transverse momentum in the 0%-30% centrality range, possibly indicating late hadronic interactions affecting the proton v sub(2).
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