113,658 research outputs found
Verifying Architectural Design Rules of the Flight Software Product Line
This paper presents experiences of verifying architectural design rules of the NASA Core Flight Software (CFS) product line implementation. The goal of the verification is to check whether the implementation is consistent with the CFS architectural rules derived from the developer's guide. The results indicate that consistency checking helps a) identifying architecturally significant deviations that were eluded during code reviews, b) clarifying the design rules to the team, and c) assessing the overall implementation quality. Furthermore, it helps connecting business goals to architectural principles, and to the implementation. This paper is the first step in the definition of a method for analyzing and evaluating product line implementations from an architecture-centric perspective
Italian center for Astronomical Archives publishing solution: modular and distributed
The Italian center for Astronomical Archives tries to provide astronomical
data resources as interoperable services based on IVOA standards. Its VO
expertise and knowledge comes from active participation within IVOA and VO at
European and international level, with a double-fold goal: learn from the
collaboration and provide inputs to the community. The first solution to build
an easy to configure and maintain resource publisher conformant to VO standards
proved to be too optimistic. For this reason it has been necessary to re-think
the architecture with a modular system built around the messaging concept,
where each modular component speaks to the other interested parties through a
system of broker-managed queues. The first implemented protocol, the Simple
Cone Search, shows the messaging task architecture connecting the parametric
HTTP interface to the database backend access module, the logging module, and
allows multiple cone search resources to be managed together through a
configuration manager module. Even if relatively young, it already proved the
flexibility required by the overall system when the database backend changed
from MySQL to PostgreSQL+PgSphere. Another implementation test has been made to
leverage task distribution over multiple servers to serve simultaneously: FITS
cubes direct linking, cubes cutout and cubes positional merging. Currently the
implementation of the SIA-2.0 standard protocol is ongoing while for TAP we
will be adapting the TAPlib library. Alongside these tools a first
administration tool (TASMAN) has been developed to ease the build up and
maintenance of TAP_SCHEMA-ta including also ObsCore maintenance capability.
Future work will be devoted at widening the range of VO protocols covered by
the set of available modules, improve the configuration management and develop
specific purpose modules common to all the service components.Comment: SPIE Astronomical Telescopes + Instrumentation 2018, Software and
Cyberinfrastructure for Astronomy V, pre-publishing draft proceeding (reduced
abstract
Multiple Access Trade Study
The Personal Access Satellite System (PASS) strawman design uses a hybrid Time Division Multiple Access (TDMA)/Frequency Division Multiple Access (FDMA) implementation. TDMA is used for the forward direction (from Suppliers to Users), and FDMA for the return direction (from Users to Suppliers). An alternative architecture is proposed that will require minimal real time coordination and yet provide a fast access method by using random access Code Division Multiple Access (CDMA). The CDMA system issues are addressed such as connecting suppliers and users, both of whom may be located anywhere in the CONUS, when the user terminals are constrained in size and weight; and providing efficient traffic routing under highly variable traffic requirements. It is assumed that bandwidth efficiency is not of paramount importance. CDMA or Spread Spectrum Multiple Access (SSMA) communication is a method in which a group of carriers operate at the same nominal center frequency but are separable from each other by the low cross correlation of the spreading codes used. Interference and multipath rejection capability, ease of selective addressing and message screening, low density power spectra for signal hiding and security, and high resolution ranging are among the benefits of spread spectrum communications
Software dependability modeling using an industry-standard architecture description language
Performing dependability evaluation along with other analyses at
architectural level allows both making architectural tradeoffs and predicting
the effects of architectural decisions on the dependability of an application.
This paper gives guidelines for building architectural dependability models for
software systems using the AADL (Architecture Analysis and Design Language). It
presents reusable modeling patterns for fault-tolerant applications and shows
how the presented patterns can be used in the context of a subsystem of a
real-life application
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