4,090 research outputs found
Adaptive architectures for future highly dependable, real time systems
Many present-day safety-critical or mission-critical military applications are deployed using intrinsically static architectures.
Often these applications are real-time systems, where late responses may cause potentially catastrophic results. Static
architectures allow system developers to certify with a high degree of confidence that their systems will provide correct
functionality during operation, but a more adaptive approach could provide some clear benefits. In particular, the ability to
dynamically reconfigure the system at run time would give increased flexibility and performance in response to unpredictable or
unplanned operating scenarios. Many current dynamic architectural approaches provide little or no features to facilitate the
highly dependable, real-time performance required by critical systems. The challenge is to provide the features and benefits of
dynamic architectural approaches while still achieving the required level of performance and dependability.
This paper describes the early results of an ongoing research programme, part funded by the Software Systems Engineering
Initiative (SSEI), aimed at developing a more adaptive software architecture for future military systems. A range of architectures
with adaptive features (including object-based, agent based and publish/subscribe) are reviewed against the desirable
characteristics of highly dependable systems. A publish/subscribe architecture is proposed as a potential way forward and a
discussion of its advantages and disadvantages for highly dependable, real-time systems is given
Next Generation Cloud Computing: New Trends and Research Directions
The landscape of cloud computing has significantly changed over the last
decade. Not only have more providers and service offerings crowded the space,
but also cloud infrastructure that was traditionally limited to single provider
data centers is now evolving. In this paper, we firstly discuss the changing
cloud infrastructure and consider the use of infrastructure from multiple
providers and the benefit of decentralising computing away from data centers.
These trends have resulted in the need for a variety of new computing
architectures that will be offered by future cloud infrastructure. These
architectures are anticipated to impact areas, such as connecting people and
devices, data-intensive computing, the service space and self-learning systems.
Finally, we lay out a roadmap of challenges that will need to be addressed for
realising the potential of next generation cloud systems.Comment: Accepted to Future Generation Computer Systems, 07 September 201
Modeling views in the layered view model for XML using UML
In data engineering, view formalisms are used to provide flexibility to users and user applications by allowing them to extract and elaborate data from the stored data sources. Conversely, since the introduction of Extensible Markup Language (XML), it is fast emerging as the dominant standard for storing, describing, and interchanging data among various web and heterogeneous data sources. In combination with XML Schema, XML provides rich facilities for defining and constraining user-defined data semantics and properties, a feature that is unique to XML. In this context, it is interesting to investigate traditional database features, such as view models and view design techniques for XML. However, traditional view formalisms are strongly coupled to the data language and its syntax, thus it proves to be a difficult task to support views in the case of semi-structured data models. Therefore, in this paper we propose a Layered View Model (LVM) for XML with conceptual and schemata extensions. Here our work is three-fold; first we propose an approach to separate the implementation and conceptual aspects of the views that provides a clear separation of concerns, thus, allowing analysis and design of views to be separated from their implementation. Secondly, we define representations to express and construct these views at the conceptual level. Thirdly, we define a view transformation methodology for XML views in the LVM, which carries out automated transformation to a view schema and a view query expression in an appropriate query language. Also, to validate and apply the LVM concepts, methods and transformations developed, we propose a view-driven application development framework with the flexibility to develop web and database applications for XML, at varying levels of abstraction
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