Abstract
Abstract. Large-scale neutron facilities such as the Spallation Neutron Source (SNS) located
at Oak Ridge National Laboratory need easy-to-use access to Department of Energy
Leadership Computing Facilities and experiment repository data. The Orbiter thick- and thinclient
and its supporting Service Oriented Architecture (SOA) based services (available at
https://nucleus.sns.gov) consist of standards-based components that are reusable and extensible
for accessing high performance computing, data and computational grid infrastructure, and
cluster-based resources easily from a user configurable interface. The primary Orbiter system
goals consist of (1) developing infrastructure for the creation and automation of virtual
instrumentation experiment optimization, (2) developing user interfaces for thin- and thickclient
access, (3) provide a prototype incorporating major instrument simulation packages, and
(4) facilitate neutron science community access and collaboration. The secure Orbiter SOA
authentication and authorization is achieved through the developed Virtual File System (VFS)
services, which use Role-Based Access Control (RBAC) for data repository file access, thinand
thick-client functionality and application access, and computational job workflow
management. The VFS Relational Database Management System (RDMS) consists of
approximately 43 database tables describing 429 user accounts with 437 groups over 451,000
directories with 739,618 repository files. Over 39 million NeXus file metadata records are
associated to the 12,794 unique NeXus file field/class names generated from the 42,894
repository NeXus files. Services that enable (a) summary dashboards of data repository status
with Quality of Service (QoS) metrics, (b) data repository NeXus file field/class name full text
search capabilities within a Google like interface, (c) fully functional RBAC browser for the
read-only data repository and shared areas, (d) user/group defined and shared metadata for data
repository files, (e) user, group, repository, and web 2.0 based global positioning with
additional service capabilities are currently available. The SNS based Orbiter SOA integration
progress with the Distributed Data Analysis for Neutron Scattering Experiments (DANSE)
software development project is summarized with an emphasis on DANSE Central Services
and the Virtual Neutron Facility (VNF). Additionally, the DANSE utilization of the Orbiter
SOA authentication, authorization, and data transfer services best practice implementations are
presented.
