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The VIATRA (visual automated model transformations) framework is the core of a transformation-based verification and validation environment for improving the quality of systems designed using the Unified Modeling Language by automatically checking consistency, completeness, and dependability requirements. In the current paper, we present an overview of (i) the major design goals and decisions, (ii) the underlying formal methodology based on metamodeling and graph transformation, (iii) the software architecture based upon the XMI standard, and (iv) several benchmark applications of the VIATRA framework.

The paper presents techniques that enable the modeling and analysis of redundancy schemes in distributed object-oriented systems. The replication manager, as a core part of the redundancy scheme, is modeled by using UML statecharts. The flexibility of the statechart-based modeling, which includes event processing and state hierarchy, enables an easy and efficient modeling of replication strategies as well as repair and recovery policies. The statechart is transformed to a Petri-net based dependability model, which also incorporates the models of the replicated objects. By the analysis of the Petri-net model the designer can obtain reliability and availability measures that can be used in the early phases of the design to compare alternatives and find dependability bottlenecks. Our approach is illustrated by an example.