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Software refactoring is the process of changing a software system in a manner that does not alter its external behavior and yet improving its internal structure. Model-driven architecture and the popularity of the UML enabled the application of refactoring at model level, which was earlier applied to software code. In this paper, we propose a multi-view integrated approach to model-driven refactoring using UML models. We selected a single model from each UML view at metamodel level to construct an integrated metamodel. We selected class diagram to represent the structural view, sequence diagram to represent the behavioral view and use case diagram to represent the functional view. We validated the proposed approach by comparing integrated refactoring approach with refactoring applied to models individually in terms of quality improvement through UML model metrics. Our results indicate that more bad smell instances can be detected using the integrated approach rather than the individual refactoring approach.

It is important that a Cyber-Physical System (CPS) with uncertainty in its behavior caused by its unpredictable operating environment, to ensure its reliable operation. One method to ensure that the CPS will handle such uncertainty during its operation is by testing the CPS with model-based testing (MBT) techniques. However, existing MBT techniques do not explicitly capture uncertainty in test ready models, i.e., capturing the uncertain expected behavior of a CPS in the presence of environment uncertainty. To fill this gap, we present an Uncertainty-Wise test-modeling framework, named as UncerTum, to create test ready models to support MBT of CPSs facing uncertainty. UncerTum relies on the definition of a UML profile [the UML Uncertainty Profile (UUP)] and a set of UML Model Libraries extending the UML profile for Modeling and Analysis of Real-Time and Embedded Systems (MARTE). UncerTum also benefits from the UML Testing Profile V.2 to support standard-based MBT. UncerTum was evaluated with two industrial CPS case studies, one real-world case study, and one open-source CPS case study from the following four perspectives: (1) Completeness and Coverage of the profiles and Model Libraries in terms of concepts defined in their underlying uncertainty conceptual model for CPSs, i.e., U-Model and MARTE, (2) Effort required to model uncertainty with UncerTum, and (3) Correctness of the developed test ready models, which was assessed via model execution. Based on the evaluation, we can conclude that we were successful in modeling all the uncertainties identified in the four case studies, which gives us an indication that UncerTum is sufficiently complete. In terms of modeling effort, we concluded that on average UncerTum requires 18.5% more time to apply stereotypes from UUP on test ready models.

Software usage model can be used as a guide when generate reliability test cases and it helps to evaluate the reliability of the software. Recent researches of deriving Markov Chain usage model from UML Model are mostly based on the UML sequence diagram and UML component diagram. But there are some problems with the existing methods: for some large software systems, there are many kinds of users who use the software in different ways, while a general usage model is not targeted and not suitable for all users. For this reason,this paper puts forward a new method to construct user-based software usage model. The method constructs usage model according to the UML activity diagram and UML use-case diagram, the model constructed by this method is user-based: the model describes, for every kind of users, the specific interacting process between the user and the system. What’s more, the model can be used to guide test cases generation.

Real-time embedded systems (RTESs) operating in safety-critical domains have to satisfy strict performance requirements in terms of task deadlines, response time, and CPU usage. Two of the main factors affecting the satisfaction of these requirements are the configuration parameters regulating how the system interacts with hardware devices, and the external events triggering the system tasks. In particular, it is necessary to carefully tune the parameters in order to ensure a satisfactory trade-off between responsiveness and usage of computational resources, and also to stress test the system with worst-case inputs likely to violate the requirements. Performance tuning and stress testing are usually manual, time-consuming, and error-prone processes, because the system parameters and input values range in a large domain, and their impact over performance is hard to predict without executing the system. In this paper, we provide an approach, based on UML/MARTE, to support the generation of system configurations predicted to achieve a satisfactory trade-off between response time and CPU usage, and stress test cases that push the system tasks to violate their deadlines. First, we devise a conceptual model that specifies the abstractions required for analyzing task deadlines, response time, and CPU usage, and provide a mapping between these abstractions and UML/MARTE. Then, we prune the UML/MARTE metamodel to only contain a purpose-specific subset of entities needed to support performance tuning and stress testing. The pruned version is a supertype of UML/MARTE, which ensures that all instances of the pruned metamodel are also instances of UML/MARTE. Finally, we cast the generation of configurations and stress test cases as two constrained optimization problems (COPs) over our conceptual model. The input data for these COPs in automatically generated via a model-to-text (M2T) transformation from models specified in the pruned UML/MARTE metamodel to the Optimization Programming Language. We validate our approach in a safety-critical RTES from the maritime and energy domain, showing that (1) our conceptual model can be applied in an industrial setting with reasonable effort, and (2) the optimization problems effectively identify configurations predicted to minimize response time and CPU usage, and stress test cases that maximize deadline misses. Based on our experience, we highlight challenges and potential issues to be aware of when using UML/MARTE to support performance tuning and stress testing in an industrial context.

Software metrics have become an essential part of software development because of their importance in estimating cost, effort, and time during the development phase. Many metrics have been proposed to assess different software quality attributes, including stability. A number of software stability metrics have been proposed at the class, architecture, and system levels. However, these metrics typically target the source code. This paper proposes a software stability metrics suite at the model level for three UML diagrams: class, use case, and sequence. These three diagrams represent the most common diagrams in the three UML views: structural, functional, and behavioral. We introduce a client–master assessment approach to avoid measurement duplication. We also theoretically and empirically validate the proposed metrics suite. We also provide examples to demonstrate the use of the proposed metrics and their application as indicators of software stability.

Duplication in software systems is an important issue in software quality assurance. While many methods for software clone detection in source code and structural models have been described in the literature, little has been done on similarity in the dynamic behaviour of interactive systems. In this paper, we present an approach to identifying near-miss interaction clones in reverse-engineered UML sequence diagrams. Our goal is to identify patterns of interaction (“conversations”) that can be used to characterize and abstract the run-time behaviour of web applications and other interactive systems. In order to leverage existing robust near-miss code clone technology, our approach is text-based, working on the level of XMI, the standard interchange serialization for UML. Clone detection in UML behavioural models, such as sequence diagrams, presents a number of challenges—first, it is not clear how to break a continuous stream of interaction between lifelines (representing the objects or actors in the system) into meaningful conversational units. Second, unlike programming languages, the XMI text representation for UML is highly non-local, using attributes to reference-related elements in the model file remotely. In this work, we use a set of contextualizing source transformations on the XMI text representation to localize related elements, exposing the hidden hierarchical structure of the model and allowing us to granularize behavioural interactions into conversational units. Then we adapt NICAD, a robust near-miss code clone detection tool, to help us identify conversational clones in reverse-engineered behavioural models. These conversational clones are then analysed to find worrisome interactions that may indicate security access violations.

Activities of specification, analysis and design of real-time systems (RTS) are highly dependent on an effective understanding of the application domain and on the thorough representation of their basic requirements. Model-based approaches using modeling languages such as UML are often applied to contribute to handle complexity of RTS development. However, UML alone does not completely represent important features associated with these systems, such as relationship with hardware elements and an effective representation of timing constraints. This article explores the combined use of UML and its profiles SysML and MARTE for modeling hardware and software requirements of RTS, with application to a case of controlling urban road traffic. The SysML profile alone does not present the representation of temporal, behavioral and performance requirements. The MARTE profile provides key resources to specify non-functional requirements for RTS, in addition to a clear description of the various relevant aspects of requirements definition of RTS, as for instance, temporal aspects and constraints. The main objective is to present the combined application of SysML with MARTE stereotypes, which enables the specification of different features of individual software requirements. Thus, in addition to the factors mentioned above, we can say that the proposed approach has an important role to specify RTS at different levels of detail and levels of abstraction.

This paper discusses an approach to generate VHDL descriptions from high-level specifications, namely UML/MARTE models that include aspect-oriented semantics. Standard UML diagrams describe the handling of functional requirements, whereas crosscutting concerns associated with the non-functional requirements are handled by aspects. UML-to-VHDL transformation is performed automatically by a script-based code generation tool named GenERTiCA. For that, mapping rules scripts define how to generate VHDL constructs from model elements, including the implementation of aspects adaptations. The generated VHDL description does not require any manual modification, in order to be fully synthesized onto a FPGA device. Some case studies have been performed to evaluate the proposed approach, including examples of real systems implemented as a FPGA-based embedded system. Obtained results show an improvement in system design in terms of an increase in system performance as well as a better utilization of FPGA reconfigurable resources. Such positive results are related to a better modularization of components achieved by using the proposed high-level approach. These case studies demonstrate the practicability of full translation of platform-independent specifications into VHDL descriptions.

UML has become a de-facto standard for design and development of object-oriented systems. On the other hand, UML includes various diagrams and notations which are missing of formal semantics. There does not exist much work to transform completely UML models to executable codes by any of the computer-aided software engineering tools because of the hidden semantics under the UML diagrams. Moreover, UML models cannot be used for automated analysis for validation and verification of the systems. Therefore, an integration of UML and semantics-based techniques such as formal methods is required to overcome such type of issues. Further, proof of correctness of software models plays a key role to ensure the quality of the final system to be developed. This paper presents a systematic method for transformation and verification of UML sequence diagrams into Z specification. The method works by translating and analysing few important combined fragments of sequence diagrams using Z notation. At first, formal specification of primary constructs is provided by capturing the hidden semantics under the diagram. Formal analysis of interaction operators namely options, alternatives, loops and break of the fragments is provided. The combined fragments are important because it allows multiple scenarios to increase an expressive power of sequence diagram by various control flows. Finally, formal analysis is provided by Z/Eves tool to check the syntax, type and proof for consistency and correctness of the specification.

Functional and non-functional properties analysis (i.e., dependability, security, or performance) ensures that requirements are fulfilled during the design phase of software systems. However, the Unified Modelling Language (UML), standard de facto in industry for software systems modelling, is unsuitable for any kind of analysis but can be tailored for specific analysis purposes through profiling. For instance, the MARTE profile enables to annotate performance data within UML models that can be later transformed to formal models (e.g., Petri nets or Timed Automatas) for performance evaluation. A performance (or throughput) estimation in such models normally relies on a whole exploration of the state space, which becomes unfeasible for large systems. To overcome this issue upper throughput bounds are computed, which provide an approximation to the real system throughput with a good complexity-accuracy trade-off. This paper introduces a tool, named PeabraiN, that estimates the performance of software systems via their UML models. To do so, UML models are transformed to Petri nets where performance is estimated based on upper throughput bounds computation. PeabraiN also allows to compute other features on Petri nets, such as the computation of upper and lower marking place bounds, and to simulate using an approximate (continuous) method. We show the applicability of PeabraiN by evaluating the performance of a building closed circuit TV system.

Use case map (UCM) is a modeling language designed to bridge the gap between requirements and high-level design artifacts. UCM graphical models describe functional requirements as scenarios using a structure of components. UCM specifies multiple scenarios abstractly in a single integrated view that facilitates understanding of the system-to-be and the early detection of inconsistent scenarios. However, once requirements have been expressed as scenarios, unified modeling language (UML) sequence diagrams are suitable for developing and presenting the details of interactions and help in the transition to a more formal level of refinement. Typically, system analysts are responsible for this transition, and they usually perform it manually, which makes subsequent design models prone to mistakes. As a result, system analysts may design an application that does not accurately realize the behavior specified in UCMs. There is therefore a need to develop a technique to transform UCM models to UML design artifacts. UML sequence diagrams are one of the most popular UML artifacts for dynamic modeling. In this paper, we present a model transformation approach from UCM notation to a UML sequence diagram to facilitate the transition from requirements to high-level design artifacts. We also present an application of the proposed model transformation to an elevator control system.

Traits, as sets of behaviors, can provide a good mechanism for reusability. However, they are limited in important ways and are not present in widely used programming and modeling languages and hence are not readily available for use by mainstream developers. In this paper, we add UML associations and other modeling concepts to traits and apply them to Java and C++ through model-driven development. We also extend traits with required interfaces so dependencies at the semantics level become part of their usage, rather than simple syntactic capture. All this is accomplished in Umple, a textual modeling language based upon UML that allows adding programming constructs to the model. We applied the work to two case studies. The results show that we can promote traits to the modeling level along with the improvement in flexibility and reusability.

Aspect-oriented modeling (AOM) emerged as a promising paradigm for handling crosscutting concerns, such as security, at the software modeling level. Most existing AOM contributions are presented from a practical perspective and lack formal syntax and semantics. In this paper, we present a practical and formal AOM framework for software security hardening. Our contributions are threefold. First, we define an AOM approach for the specification of security aspects at the unified modeling language (UML) design level. Second, we design and implement the matching and the weaving processes into UML design models. Third, we elaborate formal specifications for aspect matching and weaving in UML activity diagrams. Finally, we demonstrate the viability and the relevance of our propositions using a case study. The proposed framework is supported by a tool built on top of IBM-Rational Software Modeler.

This paper illustrates an approach for architectural design of a Learning Management System (LMS), which is verifiable against the Learning Technology System Architecture (LTSA) conformance rules. We introduce a new method for software architectural design that extends the Unified Modeling Language (UML) component diagram with the formal architectural style of Acme, hence, combines the advantages of the visual appeal of a graphical method and preciseness of a formal method. We propose some new stereotypes for UML component-connector style to incorporate Acme style within UML. A UML meta-model for the design components is also proposed to elucidate the relationships between the components. We also propose a verification method to ensure that the design artifact is holding conformance with LTSA standard. The design process as well as the verification process entails additional knowledge about the domain, which is supplied by the domain Ontology. The LTSA conformance rules, written in natural language, are represented more formally with help of Conceptual Graph representation, before using them in the verification process. Finally, we introduce a verification method that tries to find out a design pattern in the architectural design that conforms to the particular conformance rule intended to check. The verification process also introduces a goodness measure of the conformance.

UML/MARTE model-driven development approaches are gaining attention in developing real-time embedded software (RTES). UML behavioral models with MARTE annotations are used to describe timing behaviors and timing characteristics of RTES. Particularly, state machine, sequence, and timing diagrams with MARTE annotations are appropriate to understand and analyze timing behaviors of RTES. However, to guarantee software correctness and safety, timing inconsistencies in UML/MARTE should be identified in the design phase of RTES. UML/MARTE timing inconsistencies are related to modeling errors and can be hazards throughout the lifecycle of RTES. We propose a systematic approach to check timing consistency of state machine, sequence, and timing diagrams with MARTE annotations for RTES. First, we present how state machine, sequence, and timing diagrams with MARTE annotations specify the behaviors of RTES. To overcome informal semantics of UML/MARTE models, we provide formal definitions of state machine, sequence, and timing diagrams with MARTE annotations. Second, we present the timing consistency checking approach that consists of a rule-based and a model checking-based timing consistency checking. In the rule-based timing consistency checking, we validate well formedness of UML/MARTE behavioral models in timing aspects. In the model checking-based timing consistency checking, we verify whether timing behaviors of sequence and timing diagrams with MARTE annotations are consistent with the timing behaviors of state machine diagrams with MARTE annotations. We support an automated timing consistency checking tool UML/MARTE timing Consistency Analyzer for a seamless approach. We demonstrate the effectiveness and the practicality of the proposed approach by two case studies using cruise control system software and guidance and control unit software .

The real-time system (RTS) design is a major challenge due to the complexity of the considered application and the appearance of multiprocessor architectures. Most of the research in this area is interested in high abstraction level methods to decrease the design convolution. In particular, the Unified Modeling Language (UML) profiles and the Model Driven Engineering (MDE) aim at being an adequate solution to support the whole life cycle of RTS design with its real-time constraints and performance issues. Based on MDE and the Modeling and Analysis of Real-Time and Embedded systems (MARTE) profile, the present manuscript proposes an interactive partitioning scheduling of RTS running on multiprocessor architecture. A special attention is paid to the scheduling analysis step to accelerate the exploration of HW/SW space solution. Starting from a candidate solution modeled with UML activity and annotated with MARTE stereotypes, a mapping process to dynamic priority time Petri Nets (dPTPN) was defined. The considered dPTPN is able to prove the schedulability or provide a counterexample to determine the partitions causes of temporal fault. This counterexample presents a useful feedback to the HW/SW space solution explorer in the aim to exclude all solution containing the described partitions.

This paper describes UML-based foundations for model driven architecture and forward engineering of UML static models. In this paper, we propose an integrated environment for designing object-oriented enterprise models. In this projected process for Fast Prototyping, we design object models like use case diagram, sequence diagram, class diagram, etc. We use object-oriented conceptual modeling techniques to design and develop various applications like E-commerce, Banking, Comparison shopping, Ticketing, Online insurance policy management, product purchase system, etc. This paper suggests forward engineering to generate source code from object models through IBM Rational Rose software. This object oriented source code help software development team from analysis to maintenance phase as well as for round trip engineering. Due to high security concern, we have to use highly secure operating systems as a platform to run these web applications. In this regard, a number of trusted operating systems like Argus, Trusted Solaris, and Virtual Vault have been developed by various companies to handle the increasing need of security. The novel integration of security engineering with model-driven software expansion approach has various advantages. As we observe that all security checks in a Trusted Operating System is not necessary. Some non-essential security checks can be skipped by administrator to increase system performance. These non essential security checks can be easily identified at the time of requirement analysis. For example, the majority of web servers deal with pure public information. The majority of data on a web server is publicly readable and available to all users, but these users should not be capable to change the data on the web server. In this application, the need for security checks during reads from disk seems like a waste of CPU cycles. The real security need for web servers seems to be the security of write accesses, not read accesses. In this paper, we propose code generation, Class identification and Modeling for web applications through UML 2.0. Further we propose Security Performance flexibility model for the same to maintain the balance between security and performance for web applications.

Design of Embedded Systems is becoming more and more complex in terms of verify that requirements are fulfilled at different design levels. This requires the simulation of the system and the checking of its timing and functional properties. model-driven design and UML give a reasonable solution to cope with such complexity since they have mechanisms to model and verify embedded systems. This paper presents a methodology which starts from UML/MARTE sequence diagrams with timing constraints and the automatic generation of executable SystemC/TLM and VHDL code with checkers from such diagrams. The simulation of the generated model allows to verify the specified sequence of exchanged information between components while checkers allow to verify that properties and timing constraints are met. Three case studies are used to show the validity of the approach and a less than linear increase of execution time overhead due to time observation and assertion checkers.

Although the UML is considered to be the de facto standard notation with which to model software, there is still resistance to model-based development. UML modeling is perceived to be expensive and not necessarily cost-effective. It is therefore important to collect empirical evidence concerning the conditions under which the use of UML makes a practical difference. The focus of this paper is to investigate whether and how the Level of Detail (LoD) of UML diagrams impacts on the performance of maintenance tasks in a model-centric approach. A family of experiments consisting of one controlled experiment and three replications has therefore been carried out with 81 students with different abilities and levels of experience from 3 countries (The Netherlands, Spain, and Italy). The analysis of the results of the experiments indicates that there is no strong statistical evidence as to the influence of different LoDs. The analysis suggests a slight tendency toward better results when using low LoD UML diagrams, especially if used for the modification of the source code, while a high LoD would appear to be helpful in understanding the system. The participants in our study also favored low LoD diagrams because they were perceived as easier to read. Although the participants expressed a preference for low LoD diagrams, no statistically significant conclusions can be drawn from the set of experiments. One important finding attained from this family of experiments was that the participants minimized or avoided the use of UML diagrams, regardless of their LoD. This effect was probably the result of using small software systems from well-known domains as experimental materials.

In model driven architecture (MDA), system requirements are first captured by UML (unified modeling language) use cases with sequence diagrams to describe their intended use and implemented by classes of objected-oriented languages in the subsequent design stages. It is important that the dynamic behavior specified by the sequence diagrams is in full compliance with the implementation classes. This paper proposes an automatic approach and tool support for generating class contracts, which define a precondition and a postcondition for each operation of the class. The former serves as a guard to ensure invocations of the operations respect the semantics introduced by the sequence diagrams, and the latter places the system in a legal state to facilitate the succeeding operation calls. The contracts can be easily mapped to code of an object-oriented language such as Java. Thus, the approach helps to bridge the gap between the requirements and design stages of system development process. We use our model transformation tool to first generate a UML protocol state machine from the sequence diagrams, and then derive the contracts for a controller class. The transformations take into account the concurrency and critical constructs of the respective UML diagrams.

This paper follows a paper, "UML in Practice" presented at ICSE 2013. It summarizes and reflects on the discussion and additional investigation that arose from "UML in Practice." The paper provides a condensed recap of "UML in Practice" findings, explains what data were collected from which sources to inform this paper, and describes how the data were analyzed. It reports on the discussion that has arisen, summarizing responses from industry practitioners, academics teaching software engineering, and the UML community, and considers how those responses reflect on the original observations. The responses to "UML in Practice" divide (crudely) between two perspectives: (1) the observations made are familiar and unsurprizing, and match personal experience ("No shit"); or (2) the observations threaten long-held beliefs about UML use, and in particular about the status of UML as the de facto standard of software engineering, implying a need to change personal practice ("Oh, shit!").

We have developed an OWL ontology for the geologic timescale, derived from a Unified Modeling Language (UML) model that formalized the practice of the International Commission for Stratigraphy (ICS) (Cox and Richard 2005). The UML model followed the ISO/TC 211 modeling conventions, and was the basis for an XML implementation that was integrated into GeoSciML 3.0. The OWL ontology is derived using rules for generating OWL ontologies from ISO-conformant UML models, as provided in a (draft) standard from ISO/TC 211. The basic ontology is also aligned with SKOS to allow multilingual labels, and to enable delivery through a standard vocabulary interface. All versions of the International Stratigraphic Chart from 2004 to 2014 have been encoded using the ontology. Following ICS practice, the elements of the timescale retain the same identifiers across the multiple versions, though the information describing each geochronologic unit evolves with the versions of the timescale. The timescales are published through multiple web interfaces and APIs.

Modeling and Analysis of Real-Time and Embedded Systems (MARTE) is a Unified Modeling Language (UML) profile, which has been developed to model concepts specific to Real-Time and Embedded Systems (RTES). In the last 5 years, we have applied UML/MARTE to three distinct industrial problems in three industry sectors: architecture modeling and configuration of large-scale and highly configurable integrated control systems, model-based robustness testing of communication-intensive systems, and model-based environment simulator generation of large-scale RTES for testing. In this paper, we report on our experience of solving these problems by applying UML/MARTE on four industrial case studies. We highlight the challenges we faced with respect to the industrial adoption of MARTE. Based on our combined experience, we derive a framework to guide practitioners for future applications of UML/MARTE in an industrial context. The framework provides a set of detailed guidelines that help reduce the gap between the modeling notations and real-world industrial application needs.

A software model can be analysed for non-functional requirements by extending it with suitable annotations and transforming it into analysis models for the corresponding non-functional properties. For quantitative performance evaluation, suitable annotations are standardized in the "UML Profile for Modeling and Analysis of Real-Time Embedded systems" (MARTE) and its predecessor, the "UML Profile for Schedulability, Performance and Time". A range of different performance model types (such as queueing networks, Petri nets, stochastic process algebra) may be used for analysis. In this work, an intermediate "Core Scenario Model" (CSM) is used in the transformation from the source software model to the target performance model. CSM focuses on how the system behaviour uses the system resources. The semantic gap between the software model and the performance model must be bridged by (1) information supplied in the performance annotations, (2) in interpretation of the global behaviour expressed in the CSM and (3) in the process of constructing the performance model. Flexibility is required for specifying sets of alternative cases, for choosing where this bridging information is supplied, and for overriding values. It is also essential to be able to trace the source of values used in a particular performance estimate. The performance model in turn can be used to verify responsiveness and scalability of a software system, to discover architectural limitations at an early stage of development, and to develop efficient performance tests. This paper describes how the semantic gap between software models in UML+MARTE and performance models (based on queueing or Petri nets) can be bridged using transformations based on CSMs, and how the transformation challenges are addressed.

Model-driven engineering, an emerging trend in software engineering, has enabled the use of refactoring to UML models. Numerous approaches to model refactoring, problem detection, consistency management, and tool support to automate and verify refactoring are discussed and distributed across numerous research literatures. This paper provides a systematic overview of existing research in the field of model refactoring. A total of 3,295 articles, related to the field of UML model refactoring, were extracted from well-known electronic databases. A multi-stage selection process was used to ensure proper inclusion of relevant studies for review and analysis. Ninety-four primary studies were eventually selected and analyzed based on a number of different criteria: UML models considered for refactoring, formalisms used to support refactoring at the model level, important to consider when building refactoring tool support, and the effect of refactoring on model quality. The results of this review indicate that UML model refactoring is a highly active area of research. Quite a few quality techniques and approaches have been proposed in this area, but it still has some important open issues and limitations to be addressed in future work.

In the context of model-driven development of database applications with UML, the (usually relational) database schema is obtained automatically from the application's structural (class) UML model. Changes in requirements often lead to modifications of the application's structural model. Such changes, in turn, have to be propagated to the underlying database schema. Very often, especially when the system is in production with a large volume of users' live data, the data is considered to be valuable enough to be preserved through these changes. This paper describes an approach to cope with the problem of model evolution with the ultimate requirement to preserve the data stored in the database. The algorithm interactively determines differences between structural UML models before and after the changes and resolves those differences into transformations in the relational database domain.

Use case diagrams are primary artifacts used for modeling functional requirements. Use case diagrams are part of the Unified Modeling Language (UML) suite of models that has become a de facto standard for modeling object oriented languages. Each model in this suite is described by a metamodel that dictates its syntax and semantics. The use case diagram is considered the most controversial diagram in UML. Practitioners claim that the use case diagram cannot be used as a valuable artifact for requirement analysis. The main reason behind this concern is the lack of behavioral description of a use case depicted within the model. Quite a few extensions to the use case metamodel have been proposed in literature to incorporate behavioral aspect of a use case within the metamodel. All these extensions omit a few important features like generalization and most of them can only be used for model representation and cannot be used for model analysis and evaluation. In this paper, we propose an extension to the UML use case metamodel with use case behavior specification elements. The main objective of the proposed extension is to provide a complete metamodel for use case diagrams which includes representation for all its elements and relationships in a conflict-free manner and one that includes information for model analysis, evaluation, and interchange among modeling tools. In order to include all valuable information related to a use case, a number of use case representation templates were considered for the proposed extension. Simultaneously, to enable the use case models generated based on the proposed metamodel to be used for analysis, pertinent information related to model usage in analysis such as effort estimation, use case scheduling, and use case metrics evaluation were considered from published studies, tools, and paradigms and included within the proposed metamodel.

Background: The contribution of modeling in software development has been a subject of debates. The proponents of model-driven development argue that a big upfront modeling requires substantial investment, but it will payoff later in the implementation phase in terms of increased productivity and quality. Other software engineers perceive modeling activity as a waste of time and money without any real contribution to the final software product. Considering present advancement of model-based software development in software industry, we are challenged to investigate the real contribution of modeling in software development. Objective: We analyze the impacts of UML modeling, specifically the production of class and sequence diagrams, on the quality of the code, as measured by defect density, and on defect resolution time. Method: Using data of a proprietary system, we conduct post-mortem analyses to test the difference in defect density between software modules that are modeled and not modeled. Similarly, we test the difference in resolution time between defects that are related to modeled and not modeled functionality. Result: We have found that the production of UML class diagrams and sequence diagrams reduces defect density in the code and the time required to fix defects. These results are obtained after controlling for the effects of co-factors such as code coupling and complexity. Conclusion: The results confirm that not only does the production of UML class diagrams and sequence diagrams possibly help improve the quality of software, but also it possibly help increase the productivity in software maintenance.

UML is a widely-used, general purpose modeling language. But its lack of a rigorous semantics forbids the thorough analysis of designed solution, and thus precludes the discovery of significant problems at design time. To bridge the gap, the paper investigates the underlying semantics of UML state machine diagrams, along with the time-related modeling elements of MARTE, the profile for modeling and analysis of real-time embedded systems, and proposes a formal operational semantics based on extended hierarchical timed automata. The approach is exemplified on a simple example taken from the automotive domain. Verification is accomplished by translating designed models into the input language of the UPPAAL model checker.

Most Unified Modeling Language (UML) computer-aided software engineering tools have been insufficient in the development process because they provide little support for conceptual model testing. Model testing aims to ensure the correctness of a UML/OCL class diagram, or, in other words, that a given class diagram can perfectly meet the user's requirements. This study proposes the validation of class diagrams with black-box testing, a technique used to test software without focusing on the software's implementation or structure. An approach is proposed for the automatic transformation of the constraints of a UML/OCL class diagram into test cases. Following the creation of the test cases, they are executed with JUnit and the results produced are shown to the tester. To demonstrate the applicability of this approach, an effectiveness evaluation and an efficiency evaluation are performed here. Evaluation studies show that all faults included in a class diagram have been detected within an efficient time.

Aspect-oriented modeling (AOM) is a relatively recent and very active field of research, whose application has, however, been limited in practice. AOM is assumed to yield several potential benefits such as enhanced modularization, easier evolution, increased reusability, and improved readability of models, as well as reduced modeling effort. However, credible, solid empirical evidence of such benefits is lacking. We evaluate the "readability" of state machines when modeling crosscutting behavior using AOM and more specifically AspectSM, a recently published UML profile. This profile extends the UML state machine notation with mechanisms to define aspects using state machines. Readability is indirectly measured through defect identification and fixing rates in state machines, and the scores obtained when answering a comprehension questionnaire about the system behavior. With AspectSM, crosscutting behavior is modeled using so-called "aspect state machines". Their readability is compared with that of system state machines directly modeling crosscutting and standard behavior together. An initial controlled experiment and a much larger replication were conducted with trained graduate students, in two different institutions and countries, to achieve the above objective. We use two baselines of comparisons--standard UML state machines without hierarchical features (flat state machines) and standard state machines with hierarchical/concurrent features (hierarchical state machines). The results showed that defect identification and fixing rates are significantly better with AspectSM than with both flat and hierarchical state machines. However, in terms of comprehension scores and inspection effort, no significant difference was observed between any of the approaches. Results of the experiments suggest that one should use, when possible, aspect state machines along with hierarchical and/or concurrent features of UML state machines to model crosscutting behaviors.

This paper describes the results of a preliminary feasibility study of an approach to representing multiobjective combinatorial optimization problems in UML (structural constraints) and OCL (procedural constraints) and then automatically translating the representations to a constraint satisfaction solving language (Oz) for execution. The paper presents two examples of the application of the approach--a job scheduling problem and a (fixture) design problem. The main goal of this paper is to investigate directions towards a standard, graphical language for representing combinatorial optimization problems. The paper shows that for the two selected problems it is easy to represent structural constraints in UML and that procedural constraints are representable in OCL. The results also show that a developed translator automatically converts the UML/OCL representations to Oz and that the resulting Oz program performs very reasonably, in some cases outperforming the hand-written benchmark programs.

The object-oriented paradigm is widely applied in designing and implementing communication systems. Unified Modeling Language (UML) is a standard language used to model the design of object-oriented systems. A protocol state machine is a UML adopted diagram that is widely used in designing communication protocols. It has two key attractive advantages over traditional finite state machines: modeling concurrency and modeling nested hierarchical states. In a distributed communication system, each entity of the system has its own protocol that defines when and how the entity exchanges messages with other communicating entities in the system. The order of the exchanged messages must conform to the overall service specifications of the system. In object-oriented systems, both the service and the protocol specifications are modeled in UML protocol state machines. Protocol specification synthesis methods have to be applied to automatically derive the protocol specification from the service specification. Otherwise, a time-consuming process of design, analysis, and error detection and correction has to be applied iteratively until the design of the protocol becomes error-free and consistent with the service specification. Several synthesis methods are proposed in the literature for models other than UML protocol state machines, and therefore, because of the unique features of the protocol state machines, these methods are inapplicable to services modeled in UML protocol state machines. In this paper, we propose a synthesis method that automatically synthesizes the protocol specification of distributed protocol entities from the service specification, given that both types of specifications are modeled in UML protocol state machines. Our method is based on the latest UML version (UML2.3), and it is proven to synthesize protocol specifications that are syntactically and semantically correct. As an example application, the synthesis method is used to derive the protocol specification of the H.323 standard used in Internet calls.

Modern embedded systems development, due to systems complexity and multifaceted nature, requires flexible high-level design techniques and notations. In this context, model-driven approaches are gaining popularity, both in industry as well as in academy, since they offer a high degree of abstraction and provide a common framework for the design, simulation and configuration management of complex heterogeneous systems. Moreover, a great variety of languages have been emerging as customization (or profiles) of the Unified Modeling Language (UML) for the embedded system and System-on-Chip (SoC) domains. No single modeling language or profile is adequate to cover aspects and requirements of the whole system development flow. Indeed, each of these languages owns characteristics and offers modeling primitives suitable for designing at a specific abstraction level. Therefore, possible strategies for integrating such UML profiles must be determined, in order to establish a common modeling framework able to support all steps of a system design development. This paper presents the integration of two modeling languages, the SysML and the SystemC UML profiles. The integration is based on a mapping from the SysML to the SystemC UML profile for the structural aspects, while for the behavioral aspects two main models of computation, SysML control-flow graphs and SystemC Process state machines, are proposed as complementary behavioral formalisms to be adopted in a model-driven SoC design flow at platform-independent and platform-specific description level, respectively. The integration we propose, has enabled us also to refine an already defined model-driven hardware-software co-design flow, where a gap remained moving from a platform-independent design level to a platform-specific level. The refined co-design flow starts from a SysML description at a high level of design abstraction, and proceeds through a chain of refined SystemC UML models, to lower levels of design abstraction, where the more complex last-level SystemC coding is left to automation.

Modeling has become a common practice in modern software engineering. Since the mid 1990s the Unified Modeling Language (UML) has become the de facto standard for modeling software systems. The UML is used in all phases of software development: ranging from the requirement phase to the maintenance phase. However, empirical evidence regarding the effectiveness of modeling in software development is few and far apart. This paper aims to synthesize empirical evidence regarding the effectiveness of modeling using UML in software development, with a special focus on the cost and benefits.

This paper sets out in detail the development of the Unified Modeling Language and its derivatives from its beginning until the present. The paper describes the processes that were used to develop the language, the architecture and intended uses of the language, its strengths and weaknesses, and the steps that are being taken to make it ready for future developments.

The analysis and description of the application domain are important parts of the requirements engineering process. Domain descriptions are frequently represented as models in the de-facto standard unified modeling language (UML). Recent research has specified the semantics of various UML language elements for domain modeling, based on ontological considerations. In this paper, we empirically examine ontological modeling guidelines for the UML association construct, which plays a central role in UML class diagrams. Using an experimental study, we find that some, but not all, of the proposed guidelines lead to better application domain models. We use a process-tracing study to investigate in more detail the effects of ontological guidelines. The combined results indicate that ontological guidelines can improve the usefulness of UML class diagrams for describing the application domain, and thus have the potential to improve downstream system development activities and ultimately affect the successful information systems implementation.

Full implementation of the Semantic Web requires widespread availability of OWL ontologies. Manual ontology development using current OWL editors remains a tedious and cumbersome task that requires significant understanding of the new ontology language and can easily result in a knowledge acquisition bottleneck. On the other hand, abundant domain knowledge has been specified by existing database schemata such as UML class diagrams. Thus developing an automatic tool for extracting OWL ontologies from existing UML class diagrams is helpful to Web ontology development. In this paper we propose an automatic, semantics-preserving approach for extracting OWL ontologies from existing UML class diagrams. This approach establishes a precise conceptual correspondence between UML and OWL through a semantics-preserving schema translation algorithm. The experiments with our implemented prototype tool, UML2OWL, show that the proposed approach is effective and a fully automatic ontology extraction is achievable. The proposed approach and tool will facilitate the development of Web ontologies and the realization of semantic interoperations between existing Web database applications and the Semantic Web.

Due to their accuracy in describing systems, formal specifications can play an important role during forward as well as reverse engineering activities. However, besides dense mathematical expressions, their lack in visually appealing notations impedes their use and exchange among different stakeholders. One solution to this problem is to enrich the specification by other views, in most cases Unified Modelling Language (UML) diagrams. But the mapping is not trivial, and existing approaches have their impediments, among them the assignment of methods to classes--which has to be re-done by hand quite often. By the example of Z, this paper demonstrates that the situation can be improved. The new approach combines existing mapping strategies, but additionally lets the assignment of methods rest on quality-related measures. The basic idea is to balance the values of coupling for all methods within and between the UML classes. With that, two issues are addressed: firstly, the mapping of sets, types, and operations (to UML classes and UML methods) is based on reproducible measures that are intuitively comprehensible. Secondly, implementations based on the resulting UML class diagrams very likely also have comparable quality-related properties.

A key challenge to achieve a unified semantics for UML is how to handle the heterogeneity of its sublanguages. In this context, the theory of institutions provides an elegant and robust framework for programming in the large and in particular for compositionality. It can be used to define a family of formalisms which capture various UML sublanguages, and morphisms that represent the expected semantic relationships between them, resulting in a heterogeneous environment for the semantic definition of UML. The main goal of this work is to collaborate with the definition of such environment. For this purpose, we define an institution for UML 2.0 state machines. The building blocks of our institution are based on a previous semantics dealing with processing simple input events within a transition step. We also extend these semantic definitions for handling sequences of events, and then for considering runs through the state machine.

UML-B is a development process framework for Event-B based on a "UML-like" graphical formal notation that provides support for object-oriented modelling concepts, in particular, for class and state machine diagrams. However, this methodology has a gap for mapping requirements to formal specifications. To overcome this issue, we present a proposal for extending UML-B to support a conceptual model to provide an easier starting point for the actual development process. More precisely, we propose two diagrams to facilitate the passing from requirements to the initial formal model: a first one to represent system behavior based on UML 2 interaction overview diagram (IOD) and a second one for system structure based on boundary-control-entity stereotyped class diagram (BCE). We show how to translate the former into an Event-B specification and explain how to link the latter to the original UML-B using a simple ATM example as proof of concept.

UML (Unified Modeling Language) is a standard design notation which offers the state machines diagram to specify reactive software systems. The "Modeling and Analysis of Real-Time and Embedded systems" profile (MARTE) enables UML with capabilities for performance analysis. MARTE has been specialized in a "Dependability Analysis and Modeling" profile (DAM), then providing UML with dependability assets. In this work, we propose an approach for the automatic transformation of UML-DAM models into Deterministic and Stochastic Petri nets and the subsequent dependability analysis.

The article below presents the insights gained during a number of years of research dedicated to the formalisation of the Unified Modeling Language.

Model-based robustness testing requires precise and complete behavioral, robustness modeling. For example, state machines can be used to model software behavior when hardware (e.g., sensors) breaks down and be fed to a tool to automate test case generation. But robustness behavior is a crosscutting behavior and, if modeled directly, often results in large, complex state machines. These in practice tend to be error prone and difficult to read and understand. As a result, modeling robustness behavior in this way is not scalable for complex industrial systems. To overcome these problems, aspect-oriented modeling (AOM) can be employed to model robustness behavior as aspects in the form of state machines specifically designed to model robustness behavior. In this paper, we present a RobUstness Modeling Methodology (RUMM) that allows modeling robustness behavior as aspects. Our goal is to have a complete and practical methodology that covers all features of state machines and aspect concepts necessary for model-based robustness testing. At the core of RUMM is a UML profile (AspectSM) that allows modeling UML state machine aspects as UML state machines (aspect state machines). Such an approach, relying on a standard and using the target notation as the basis to model the aspects themselves, is expected to make the practical adoption of aspect modeling easier in industrial contexts. We have used AspectSM to model the crosscutting robustness behavior of a videoconferencing system and discuss the benefits of doing so in terms of reduced modeling effort and improved readability.

Technical books of each subject area denote the level of maturity and knowledge demand in that area. According to the Google Books database, about 208 Unified Modeling Language (UML) books have been published from its inception in 1997 until 2009. While various book reviews are frequently published in various sources (e. g., IEEE Software Bookshelf), there are no studies to classify UML books into meaningful categories. Such a classification can help researchers in the area to identify trends and also reveal the level of activity in each sub-area of UML. The statistical survey reported in this article intends to be a first step in classification and trend analysis of the UML books published from 1997 to 2009. The study also sheds light on the quantity of books published in different focus areas (e. g., UML's core concepts, patterns, tool support, Object Constraint Language and Model-Driven Architecture) and also on different application domains (e. g., database modeling, web applications, and real-time systems). The trends of book publications in each sub-area of UML are also used to track the level of maturity, to identify possible Hype cycles and also to measure knowledge demand in each area. © 2011 Springer-Verlag.

Mechatronic systems are composed of mechanical, electronic and software parts. Recently, software processes and modeling notations traditionally used in software engineering have been used in building mechatronic systems. One of the modeling notations used in software design is the Unified Modeling Language (UML), a visual modeling language. In this paper, an analysis of UML in the building of mechatronic systems is presented.

Software and embedded system companies today encounter problems related to requirements management tool integration, incorrect tool usage, and lack of traceability. This is due to utilized tools with no clear meta-model and semantics to communicate requirements between different stakeholders. This paper presents a comprehensive meta-model for requirements management. The focus is on software and embedded system domains. The goal is to define generic requirements management domain concepts and abstract interfaces between requirements management and system development. This leads to a portable requirements management meta-model which can be adapted with various system modeling languages. The created meta-model is prototyped by translating it into a UML profile. The profile is imported into a UML tool which is used for rapid evaluation of meta-model concepts in practice. The developed profile is associated with a proof of concept report generator tool that automatically produces up-to-date documentation from the models in form of web pages. The profile is adopted to create an example model of embedded system requirement specification which is built with the profile.

This paper reports on experiences from using a UML-based method for trust analysis in an industrial project. The overall aim of the trust analysis method is to provide a sound basis for making trust policy decisions. The method makes use of UML sequence diagrams extended with constructs for probabilistic choice and subjective belief, as well as the capture of policy rules. The trust analysis method is evaluated with respect to a set of criteria. The industrial project focused on the modeling and analysis of a public electronic procurement (eProcurement) system making use of a validation authority service for validating electronic certificates and signatures.

Several safety-related standards exist for developing and certifying safety-critical systems. System safety assessments are common practice and system certification according to a standard requires submitting relevant system safety information to appropriate authorities. The RTCA DO-178B standard is a software quality assurance, safety-related standard for the development of software aspects of aerospace systems. This research introduces an approach to improve communication and collaboration among safety engineers, software engineers, and certification authorities in the context of RTCA DO-178B. This is achieved by utilizing a Unified Modeling Language (UML) profile that allows software engineers to model safety-related concepts and properties in UML, the de facto software modeling standard. A conceptual meta-model is defined based on RTCA DO-178B, and then a corresponding UML profile, which we call SafeUML, is designed to enable its precise modeling. We show how SafeUML improves communication by, for example, allowing monitoring implementation of safety requirements during the development process, and supporting system certification per RTCA DO-178B. This is enabled through automatic generation of safety and certification-related information from UML models. We validate this approach through a case study on developing an aircraft's navigation controller subsystem.

Unified Modeling Language (UML) is widely used as a system level specification language in embedded system design. Due to the increasing complexity of embedded systems, the analysis and validation of UML specifications is becoming a challenge. UML activity diagram is promising to modeling the overall system behavior. However, lack of techniques for automated test case generation is one major bottleneck in the UML activity diagram validation. This article presents a methodology for automatically generating test cases based on various model checking techniques. It makes three primary contributions: First, we propose coverage-driven mapping rules that can automatically translate activity diagram to formal models. Next, we present a procedure for automatic property generation according to error models. Finally, we apply various model checking based test case generation techniques to enable efficient test case generation. Our experimental results demonstrate that our approach can reduce the validation effort drastically by reducing both test case generation time and required number of test cases to achieve a functional coverage goal.