PhD Oral Exam - Mahin Abbasipour, Electrical and Computer Engineering
When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.
Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.
To meet user requirements, systems can be built from Commercial-Off-The-Shelf (COTS) components, potentially from different vendors. However, the gap between the requirements referring to the overall system and the components to build the system from can be large. To close the gap, it is required to decompose the requirements to a level where they can be mapped to components.
When the designed system is deployed and ready for operations, its services are sold and provided to customers. One important goal for service providers is to optimize system resource utilization while ensuring the quality of service expressed in the Service Level Agreements (SLAs). For this purpose, the system can be reconfigured dynamically according to the current workload to satisfy the SLAs while using only necessary resources. To manage the reconfiguration of the system at runtime, a set of previously defined patterns called elasticity rules can be used. In elasticity rules, the actions that need to be taken to reconfigure the system are specified. An elasticity rule is generally invoked by a trigger, which is generated in reaction to a monitoring event.
In this thesis, we propose a model-driven management framework which aims at user requirements satisfaction, SLA compliance management and enabling dynamic reconfiguration by reusing the design information at runtime.
An approach has been developed to derive automatically a valid configuration starting from low level requirements called service configurations. However, the service configurations are far from requirements a user would express. To generate a system configuration from user requirements and alleviate the work of designer, we generate service configurations by decomposing functional user requirements to the level where components can be selected and put together to satisfy the user requirements. We integrated our service configuration generator with the previous configuration generator.
In our framework, we reuse the information acquired from system configuration and dimensioning to generate elasticity rules offline. We propose a model driven approach to check the compliance of SLAs and generate triggers for invoking applicable elasticity rules when system reconfiguration is required. For handling multiple triggers generated at the same time, we propose a solution to automatically correlate the actions of invoked elasticity rules, when required. The framework consists of a number of metamodels and a set of model transformations. We use the Unified Modeling Language (UML) and its profiling mechanism to describe all the artifacts in the proposed framework. We implement the profiles using Eclipse Modeling Framework (EMF) and Papyrus. To implement the processes, we use the Atlas Transformation Language (ATL). We also use the APIs of the Object Constraint Language (OCL) in the Eclipse environment to develop a tool for checking constraints and generating triggers.