| Dependable distributed system typically utilize a hierarchy of protocols to provide for reliable and timely services. Such protocols have both dependability and real-time attributes, and the analysis of these protocols is a problem of growing complexity. The development of precise and accurate formal specifications of these protocols and their subsequent formal verification to gain assurance have been a great challenge. Exploiting the inherent modularity in the design of most dependable protocols, in this thesis, we present our modular approach to specification composition and verification of dependable distributed protocol. In particular, we consider redundancy management protocols that are needed to manage redundant resources used in the system for dependability purposes. Utilizing building-block protocols inherently used in redundancy management protocols, we perform compositional specification and verification of a checkpointing and recovery protocol based on them. The key idea is that if a library of these basic components, like the primitives and sub-protocols are being formulated, then these elements aid in systematic and hierarchical development of dependable distributed protocols. The main contribution of this thesis to illustrate the fact that by defining a priori validated building-blocks for dependable distributed protocols, larger and more complex protocols can be easily specified and verified. For a mechanical support in formal verification process, we use formal tools such as Specware and PVS. |
