Research On Software Architecture Technologies Of Self-Adaptive Systems

Nowadays, with the coming age of diversity of computing, web computing and mobility computing, more and more software systems exhibit some novel properties, such as ultra larger scale, more complex structure, increasing costs on management and maintenance, more flexibility to handle the changes of the situated environments. Hence, self-adaptive software systems are urgent for various applications such as finance, telecom, power, transportation, defense and so on.Self-adaptive systems usually are situated in open, dynamic environments, can perceive the changes of the environments, and keep their functions and performances at satisfied levels by adjusting their strucutures and behaviours. Though many attentions have been paid on the researches and practices of the self-adaptive systems in academic and industry communities, it is still a great challenge to specify, analyse, design and implement self-adaptive systems in an effective and systematic way.Software architecture depicts system configuration status from a global and macro perspective, which is helpful to monitor the properties in system level, check the important constraints and exhibit evolutions. Therefore, software architecture can decrease and control complexity of self-adaptive systems effectively. The thesis investigates the fundermental theory and technology of software architecture for self-adaptive systems, such as mechanism, language facility, semantics model, property verification, and development environment. The details and contributions of the thesis are described as follows.1. Implementation technology and mechanism of self-adaptive components based on agent technology. The components of self-adaptive systems are abstracted and constructed as self-adaptive software agents. The dynamic binding mechanism is presented, with which self-adaptive agent can adjust its structure and behaviour by binding various behaviour specifications when situated environment changes. The technique framework to construct and run the self-adaptive agents is also put forward. The dynamic binding mechanism is formally specified.2. ADL (Architecture Description Language) for self-adaptive systems. To specify the software architecture and verify its properties of self-adaptive systems, we present a novel ADL called Bi-ADL. Bi-ADL can be used to describe software architecture of self-adaptive systems from the several perspectives such as environment, structure and behaviour. It also can specify self-adaptation for component and configuration, and express structural and behavioural constraints of system evolutions.3. Semantics model and properties verification of Bi-ADL. The thesis presents the Bi-ADL's semantics model based on bigraph theory. We use Bigraphs to describe environment, structure and behaviour, and use reaction rules to express the changes of them. The approaches to validating some important properties of self-adaptive software systems are also presented, including behaviour consistency, system integrity, consistency of self-adaptive strategies, and consistency of system and its architectural style.4. Supporting platform SArchStudio to describe, analyze and design software architecture of self-adaptive systems. SArchStudio consists of a number of toolkits, such as Bi-ADL syntax editior, semantics transform, properties verification, self-adaptive agent development environment, etc, which can support for the whole flow for developing self-adaptive systems. Case is studied to illustrate our approaches and toolkits.