A component framework of a distributed control systems family
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|Publish Date:|| 2005-05-20
|Thesis type:||Doctoral Dissertation
|Defence Note:||Academic Dissertation to be presented, with the assent of the Faculty of Science, University of Oulu, for the public discussion in the Auditorium L10, Linnanmaa, on January 21st, 2000, at 12 o’clock noon.
A component framework is based on a software architecture, a set of components and their interaction mechanisms. This thesis examines the component-based software development by reviewing the requirements for a component framework development, proposing a model of a component framework of a distributed control systems family and demonstrating results with cases drawn from the control systems families.
The product families of the machine control systems, process control systems and manufacturing systems are studied to set the requirements for the component framework. Three main problems are discovered. A lack of appropriate modelling methods prevents describing product features and variability at the software architecture level. Interoperability and adaptability of software components that are required in the integration phase are inadequate in most cases. Furthermore, integrators and maintenance staff also need support software for extending and upgrading systems.
The component framework of a distributed control systems family introduces two dimensions: tiers and elements. The three tiers of the component framework define the subsystems in the first tier, integration platform in the second tier, and the product family in the third their. The tiers explain the domain, technology and business viewpoints of the framework correspondingly. The elements define the product features, software architecture, components and their interaction mechanisms. The development and utilisation of the component framework have three main tasks, described as the viewpoints of the component-based software development, concurrent software engineering and software configuration management.
The development of the component framework is presented by the development of the reuse assets: the product features, product-family architecture and software components. The architecture styles, key-mechanisms, services and components of each tier are depicted. The framework mixes agent, layered, client-server and rule-based system architectures and their mechanisms to provide a coherent solution for software flexibility and stability required by the product families.
The results are analysed as regards the evaluation criteria, set for the component framework as the result of the problem analysis. Variability and adaptability are examined at the architecture and component level, as well as the interoperability of tiers, services and applications and interchangeability of product features and components.
The adaptive approach restricts the affects of the changes in the business, technology and application domain to the corresponding tiers that provide their own mechanisms for adaptability. The integration tier could be reused community-wide, whereas the subsystem tier is domain-specific and the product-family tier is always an organisation-dependent solution.
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