Graphic modeling in Distributed Autonomous and Asynchronous Automata (DA3)

Abstract

Automated verification of distributed systems becomes very important in distributed computing. The graphical insight into the system in the early and late stages of the project is essential. In the design phase, the visual input helps to articulate the collaborative distributed components clearly. The formal verification gives evidence of correctness or malfunction, but in the latter case, graphical simulation of counterexample helps for better understanding design errors. For these purposes, we invented Distributed Autonomous and Asynchronous Automata (DA3), which have the same semantics as the formal verification base—Integrated Model of Distributed Systems (IMDS). The IMDS model reflects the natural characteristics of distributed systems: unicasting, locality, autonomy, and asynchrony. Distributed automata have all of these features because they share the same semantics as IMDS. In formalism, the unified system definition has two views: the server view of the cooperating distributed nodes and the agent view of the migrating agents performing distributed computations. The automata have two formally equivalent forms that reflect two views: Server DA3 for observing servers exchanging messages, and Agent DA3 for tracking agents, which visit individual servers in their progress of distributed calculations. We present the DA3 formulation based on the IMDS formalism and their application to design and verify distributed systems in the Dedan environment. DA3 formalism is compared with other concepts of distributed automata known from the literature.

Formal Verification of the European Train Control System (ETCS) for Better Energy Efficiency Using a Timed and Asynchronous Model

“…The T-IMDS model is presented in the DA 3 formalism (Distributed Autonomous and Asynchronous Automata [51]), which is the graphic counterpart of IMDS, with identical semantics. We used the transitions of those automata above informally.…”

Formal verification of BPMN diagrams in Integrated Model of Distributed Systems (IMDS)

“…Its authors also provide a set of benchmarks [24] that are used during tests of the proposed automatic tool. Work [25] proposes verification using process automata that can be compared to our IMDS graphical view [26]; however, this technique concerns checking a single BPMN pool. In [20], the Bogor LTL checker is used to verify the workflows.…”

Temporal Verification of Relay-Based Railway Traffic Control Systems Using the Integrated Model of Distributed Systems

“…However, we believe that formalism is up to the task. IMDS is attractive because it has a graphical version of DA 3 distributed automata [9], allowing the design of models in terms of automata, consistent with the intuition of engineers performing verification. The automata-based model fully complies with the IMDS algebraic formalism in which the verification is performed.…”

“…The graphic formalism for modeling, having the same semantics as the algebraic model for verification, so there is no need to translate from the description of the system to the verification language [9]; • A limited set of examined features, but verified automatically, without specifying temporal formulas; these are deadlocks and termination; • Finding partial deadlocks and termination concerning parts of the system or even its individual elements; while the rest of the system may not experience the effects of partial deadlocks/termination, most verifiers find only total deadlocks/termination, and the user has to ask for partial properties by formulating appropriate temporal formulas; • Fairness of verification is a little-known feature among non-specialists; however, most verifiers are unfair or weakly fair, which can lead to the detection of non-existent deadlocks [10].…”