Hammer, Moritz (2009): How To Touch a Running System: Reconfiguration of Stateful Components. Dissertation, LMU München: Faculty of Mathematics, Computer Science and Statistics 

PDF
hammer_moritz.pdf 4Mb 
Abstract
The increasing importance of distributed and decentralized software architectures entails more and more attention for adaptive software. Obtaining adaptiveness, however, is a difficult task as the software design needs to foresee and cope with a variety of situations. Using reconfiguration of components facilitates this task, as the adaptivity is conducted on an architecture level instead of directly in the code. This results in a separation of concerns; the appropriate reconfiguration can be devised on a coarse level, while the implementation of the components can remain largely unaware of reconfiguration scenarios. We study reconfiguration in component frameworks based on formal theory. We first discuss programming with components, exemplified with the development of the cmc model checker. This highly efficient model checker is made of C++ components and serves as an example for componentbased software development practice in general, and also provides insights into the principles of adaptivity. However, the component model focuses on high performance and is not geared towards using the structuring principle of components for controlled reconfiguration. We thus complement this highly optimized model by a message passingbased component model which takes reconfigurability to be its central principle. Supporting reconfiguration in a framework is about alleviating the programmer from caring about the peculiarities as much as possible. We utilize the formal description of the component model to provide an algorithm for reconfiguration that retains as much flexibility as possible, while avoiding most problems that arise due to concurrency. This algorithm is embedded in a general fourstage adaptivity model inspired by physical control loops. The reconfiguration is devised to work with stateful components, retaining their data and unprocessed messages. Reconfiguration plans, which are provided with a formal semantics, form the input of the reconfiguration algorithm. We show that the algorithm achieves perceived atomicity of the reconfiguration process for an important class of plans, i.e., the whole process of reconfiguration is perceived as one atomic step, while minimizing the use of blocking of components. We illustrate the applicability of our approach to reconfiguration by providing several examples like faulttolerance and automated resource control.
Item Type:  Thesis (Dissertation, LMU Munich) 

Keywords:  software engineering, components, reconfiguration, formal model 
Subjects:  600 Natural sciences and mathematics > 510 Mathematics 600 Natural sciences and mathematics 
Faculties:  Faculty of Mathematics, Computer Science and Statistics 
Language:  English 
Date Accepted:  7. May 2009 
1. Referee:  Wirsing, Martin 
Persistent Identifier (URN):  urn:nbn:de:bvb:19101923 
MD5 Checksum of the PDFfile:  7f12f1040e81b8dc04e2e47dfd7f30c8 
Signature of the printed copy:  0001/UMC 17844 
ID Code:  10192 
Deposited On:  15. Jun 2009 13:49 
Last Modified:  16. Oct 2012 08:28 