UML 2.0 interactions with OCL/RT constraints

The use of formal methods at early stages of software development contributes to the reliability and robustness of the system to be constructed. Int his context, real-time system development benefits from the construction of behavioral models in order to verify the correct satisfaction of time constraints. The Unified Modeling Language (UML) is a software specification language widely used by the industry and the academia. Nevertheless, its version 2.0 lacks a formal semantics for the development of provably-correct models. In addition, its constraint specification language, Object Constraint Language (OCL), has limitations for its use in behavioral models of real-time systems. This work concerns the inter-component behavioral specification of real-time systems. Such behavior is described using the UML 2.0 Interactions language extended for the inclusion of time constraints using the OCL for Real Time (OCL/RT) language. The main problem addressed in this work is the definition of a formal semantics for the fusion of both languages. The semantics allows recognizing valid and invalid behaviors of a system with time constraints. Intended for formal verification, an analysis of the properties derived from the semantics is also done. In particular, the notions of refinement of interactions and refinement of constraints are explored. Finally, the proposal is compared with related works and its practical application is studied in order to analyze its benefits and weaknesses. This work contributes to the formalization of concepts widely used in practice and, inconsequence, to its inclusion in modeling and formal reasoning tools. More-over, the expressivity of the UML 2.0 Interactions language is augmented in order to support complex real-time constraints, not expressable until this moment

TURTLE-P: a UML profile for the formal validation of critical and distributed systems

The timed UML and RT-LOTOS environment, or TURTLE for short, extends UML class and activity diagrams with composition and temporal operators. TURTLE is a real-time UML profile with a formal semantics expressed in RT-LOTOS. Further, it is supported by a formal validation toolkit. This paper introduces TURTLE-P, an extended profile no longer restricted to the abstract modeling of distributed systems. Indeed, TURTLE-P addresses the concrete descriptions of communication architectures, including quality of service parameters (delay, jitter, etc.). This new profile enables co-design of hardware and software components with extended UML component and deployment diagrams. Properties of these diagrams can be evaluated and/or validated thanks to the formal semantics given in RT-LOTOS. The application of TURTLE-P is illustrated with a telecommunication satellite system

Verifying service continuity in a satellite reconfiguration procedure: application to a satellite

The paper discusses the use of the TURTLE UML profile to model and verify service continuity during dynamic reconfiguration of embedded software, and space-based telecommunication software in particular. TURTLE extends UML class diagrams with composition operators, and activity diagrams with temporal operators. Translating TURTLE to the formal description technique RT-LOTOS gives the profile a formal semantics and makes it possible to reuse verification techniques implemented by the RTL, the RT-LOTOS toolkit developed at LAAS-CNRS. The paper proposes a modeling and formal validation methodology based on TURTLE and RTL, and discusses its application to a payload software application in charge of an embedded packet switch. The paper demonstrates the benefits of using TURTLE to prove service continuity for dynamic reconfiguration of embedded software

ArchiTRIO: a UML-compatible language for architectural description and its formal semantics

ArchiTRIO [14] is a formal language, which complements UML 2.0 concepts with a formal, logic-based notation that allows users to state system-wide properties, both static and dynamic, including real- time constraints. In this paper we present the semantics of the core con- cepts of the ArchiTRIO language. As the core elements of ArchiTRIO coincide with those of UML 2.0 (operation, interface, port, class), the semantics of ArchiTRIO provides also a formal definition for the basic concepts on which UML 2.0 is built

On the semantics of redefinition, specialization and subsetting of associations in UML (extended version)

The definition of the exact meaning of conceptual modeling concepts is considered a relevant issue since it enhances their effective and appropriate use by designers and facilitates the automatic processing of the models where they are included. Three related concepts that permit to improve the definition of an association in UML and which still lack of a formal semantic definition are: association redefinition, association specialization and association subsetting. This paper formalizes their semantics and points out the similarities and differences that exist among them. The formalization we propose is based on the meta-modelling approach and a semantic domain composed of a set of basic UML concepts and OCL expressions, which have a previous formal definition in the literature and which are well-understood.Preprin

Model-Based Run-time Verification of Software Components by Integrating OCL into Treaty

Model Driven Development is used to improve software quality and efficiency by automatically transforming abstract and formal models into software implementations. This is particularly sensible if the model’s integrity can be proven formally and is preserved during the model’s transformation. A standard to specify software model integrity is the Object Constraint Language (OCL). Another topic of research is the dynamic development of software components, enabling software system composition at component run-time. As a consequence, the system’s verification must be realized during system run-time (and not during transformation or compile time). Many established verification techniques cannot be used for run-time verification. A method to enable model-based run-time verification will be developed during this work. How OCL constraints can be transformed into executable software artifacts and how they can be used in the component-based system Treaty will be the major task of this diploma thesis.Modellgetriebene Entwicklung dient der Verbesserung von Qualität und Effizienz in der Software-Entwicklung durch Automatisierung der notwendigen Transformationen von abstrakten bzw. formalen Modellen bis zur Implementierung. Dies ist insbesondere dann sinnvoll, wenn die Integrität der ursprünglichen Modelle formal bewiesen werden kann und durch die Transformation gewährleistet wird. Ein Standard zur Spezifikation der Integrität von Softwaremodellen ist die Object Constraint Language (OCL). Eine weitere Forschungsrichtung im Software-Engineering ist die Entwicklung von dynamischen Komponenten-Modellen, die die Komposition von Softwaresystemen im laufenden Betrieb ermöglichen. Dies bedeutet, dass die Systemverifikation im laufenden Betrieb realisiert werden muss. Die meisten der etablierten Verifikationstechniken sind dazu nicht geeignet. In der Diplomarbeit soll ausgehend von diesem Stand der Technik eine Methode zur modellbasierten Verifikation zur Laufzeit entwickelt werden. Insbesondere soll untersucht werden, wie OCL-Constraints zur Laufzeit in ausführbare Software-Artefakte übersetzt und in dem komponentenbasierten System Treaty verwendet werden können

A logic-based approach for the verification of UML timed models

This article presents a novel technique to formally verify models of real-time systems captured through a set of heterogeneous UML diagrams. The technique is based on the following key elements: (i) a subset of Unified Modeling Language (UML) diagrams, called Coretto UML (C-UML), which allows designers to describe the components of the system and their behavior through several kinds of diagrams (e.g., state machine diagrams, sequence diagrams, activity diagrams, interaction overview diagrams), and stereotypes taken from the UML Profile for Modeling and Analysis of Real-Time and Embedded Systems; (ii) a formal semantics of C-UML diagrams, defined through formulae of the metric temporal logic Tempo Reale ImplicitO (TRIO); and (iii) a tool, called Corretto, which implements the aforementioned semantics and allows users to carry out formal verification tasks on modeled systems. We validate the feasibility of our approach through a set of different case studies, taken from both the academic and the industrial domain

cmUML - A UML based framework for formal specification of concurrent, reactive systems

Complex software systems possess concurrent and reactive behaviors requiring precise specifications prior to development. Lamport's transition axiom method is a formal specification method which combines axiomatic and operational approaches. On the other hand Unified Modeling Language (UML), a de facto industry standard visual language, lacks suitable constructs and semantics regarding concurrency aspects. Though UML includes action semantics, its higher level constructs and object semantics are inconsistent. Motivated by Lamport's approach, this paper proposes a UML based specification framework 'cmUML' ('cm' for concurrent modules) for formal specification of concurrent, reactive systems without object level diagrams and OCL. The framework integrates higher level diagrams of UML and addresses various concurrency issues including exception handling. It combines UML-RT and UML// SPT profile as the latter defines a core package for concurrency and causality. Further the framework includes the characteristic safety and liveness aspects of concurrent systems. The proposed framework is in contrast with existing approaches based on low level primitives (semaphore, monitors). The paper includes several specification examples validating the proposed framework