| dc.description.abstract | Developing distributed real-time and embedded (DRE) systems require effective strategies to simultaneously handle the challenges of networked systems, enterprise systems, and embedded systems. Component-based model is gaining prominence for the development of DRE systems because of its emphasis on composability, reuse, excellent support for separation of concerns, and explicit staging of development phases. Despite the advances in component technology, developing highly available DRE systems remains challenging because of several reasons; First, availability concerns crosscut functional, deployment, and other QoS concerns of DRE systems, which makes reasoning about simultaneous QoS requirements extremely difficult. Second, fault-tolerance provisioning affects nearly all the phases of system lifecycle including specification, design, composition, deployment, configuration, and run-time. Codifying the availability requirements in system artifacts corresponding to the various lifecycle phases remains challenging due to lack of a coherent approach. Finally, multi-tier architecture and non-deterministic behavior of DRE systems combined with the need to meet end-to-end deadlines even during failures give rise to unique end-to-end reliability issues. General-purpose middleware infrastructures often do not support such highly domain-specific end-to-end reliability and failure recovery requirements.
This dissertation presents a model-driven framework to coherently address the issues arising during the development of highly available component-based DRE systems. First, a domain-specific modeling language called Component QoS Modeling Language (CQML) is presented that separates systemic concerns, such as composition, deployment, and QoS to enhance comprehension and design-time reasoning. Second, a multi-stage model-driven process named GeneRative Aspects for Fault Tolerance (GRAFT) is presented that synthesizes various system artifacts to provision domain-specific end-to-end reliability and recovery semantics using model-to-model, model-to-text, model-to-code transformations. Finally, the orphan request problem arising due to the side-effects of replication in the context of non-deterministic stateful components is addressed. This dissertation presents Group-failover protocol that ensures that the data in multi-tier real-time systems is both consistent and timely even in the case of failures.
Although model-driven engineering (MDE) is used extensively in this dissertation, effective techniques for a key step in MDE, model traversal, are still maturing. In the course of this research, limitations in the current model traversal approaches were addressed in Language for Embedded Query and Traversal (LEESA), which is presented here as a language-centric solution for writing succinct, generic, reusable model traversals. | |
