Jan Hendrik Hausmann

Dynamic meta modeling: a graphical approach to the operational semantics of behavioral diagrams in UML

In this paper, dynamic meta modeling is proposed as a new approach to the operational semantics of behavioral UML diagrams. The dynamic meta model extends the well-known static meta model by a specification of the systems dynamics by means of collaboration diagrams. In this way, it is possible to define the behavior of UML diagrams within UML. The conceptual idea is inherited from Plotkins structured operational semantics (SOS) paradigm, a style of semantics specification for concurrent programming languages and process calculi: Collaboration diagrams are used as deduction rules to specify a goal-oriented interpreter for the language. The approach is exemplified using a fragment of UML state-chart and object diagrams. Formally, collaboration diagrams are interpreted as graph transformation rules. In this way, dynamic UML semantics can be both mathematically rigorous so as to enable formal specifications and proofs and, due to the use of UML notation, understandable without prior knowledge of heavy mathematic machinery. Thus, it can be used as a reference by tool developers, teachers, and advanced users.

Detection of conflicting functional requirements in a use case-driven approach: a static analysis technique based on graph transformation

In object-oriented software development, requirements of different stakeholders are often manifested in use case models which complement the static domain model by dynamic and functional requirements. In the course of development, these requirements are analyzed and integrated to produce a consistent overall requirements specification. Iterations of the model may be triggered by conflicts between requirements of different parties.However, due to the diversity, incompleteness, and informal nature, in particular of functional and dynamic requirements, such conflicts are difficult to find. Formal approaches to requirements engineering, often based on logic, attack these problems, but require highly specialized experts to write and reason about such specifications.In this paper, we propose a formal interpretation of use case models consisting of UML use case, activity, and collaboration diagrams. The formalization, which is based on concepts from the theory of graph transformation, allows to make precise the notions of conflict and dependency between functional requirements expressed by different use cases. Then, use case models can be statically analyzed, and conflicts or dependencies detected by the analysis can be communicated to the modeler by annotating the model.An implementation of the static analysis within a graph transformation tool is presented.

Model-based discovery of Web services

Web services are software components that can be discovered and employed at runtime using the Internet. Conflicting requirements towards the nature of these services can be identified. From a business perspective, Web services promise to enable the formation of ad-hoc cooperations on a global scale. From a technical perspective, a high degree of standardization and rigorous specifications are required to enable the automated integration of Web services. A suitable technology for Web services has to mediate these needs for flexibility and stability. In this paper a new approach to the description of Web service semantics is introduced. It is a visual approach based on the use of software models and graph transformations and allows for the description of innovative services while providing a precise matching concept. An implementation using current standards and tools is available.

Visualizing model mappings in UML

Whenever multiple representations or models of a system exist, there is the possibility of defining how they relate. In model driven software development, it is essential that these mappings are defined precisely and automated as far as possible: they form the basis for generation of code and other models from a model, for reconciliation and management of consistency between models, and even for the definition of modeling languages themselves. A standard way of defining software modeling languages is metamodeling, which involves the construction of an object model of the syntax and, optionally, semantics of the language, using the diagrammatic syntax of the Unified Modeling Language (UML). This paper proposes an extension to UML for expressing mappings between models using diagrams, and illustrates how the extension can be used in metamodeling. The extension is inspired by mathematical relations and corrects a deficiency in the concept of association in class diagrams. The notation of object diagrams is also extended to allow particular instances of a relation to be presented.

Model-Based Development of Web Services Descriptions Enabling a Precise Matching Concept

Web services are software components that can be discovered and employed at runtime using the Internet. Conflicting requirements towards the nature of these services can be identified. From a business perspective, Web services promise to enable the formation of ad-hoc cooperations on a global scale. From a technical perspective, a high degree of standardization and rigorous specifications are required to enable the automated integration of Web services. A suitable technology for Web services has to mediate these needs for flexibility and stability. To be usable in practice, this technology has to be aligned to standard software engineering practice to allow for a seamless development of Web service enabled components. In this paper, we introduce a new approach to the description of Web services. It is a visual approach based on the use of software models and graph transformations and allows for the flexible description of innovative services while providing a precise matching concept. A methodology enabling the seamless development of such Web service descriptions in the context of a standard model-based development approach is presented.

Towards dynamic meta modeling of UML extensions: an extensible semantics for UML sequence diagrams

The unified modeling language (UML) still lacks a formal and commonly agreed specification of its semantics that also accounts for UMLs built-in semantic variation points and extension mechanisms. The semantic specification of such extensions must be formally integrated and consistent with the standard UML semantics without changing the latter. Feasible semantic approaches must thus allow advanced UML modelers to define domain-specific language extensions in a precise, yet usable manner. We proposed dynamic meta modeling for specifying operational semantics of UML behavioral diagrams based on UML collaboration diagrams that are interpreted as graph transformation rules. Herein we show how this approach can be advanced to specify the semantics of UML extensions. As a case study we specify the operational semantics of UML sequence diagrams and extend this specification to include features for modeling multimedia applications.

Dynamic Meta Modeling with Time: Specifying the Semantics of Multimedia Sequence Diagrams

Abstract UML offers different diagram types to model behavior and dynamics of software systems. In some domains like embedded real-time systems or multimedia systems, it is necessary to include specifications of time since the correctness of these applications depends on the fulfillment of temporal requirements in addition to functional requirements. UML thus already incorporates language features to model time and temporal constraints. Such model elements must have an equivalent in the semantic domain. We have proposed Dynamic Meta Modeling (DMM) as a means for the specification of the formal operational semantics of UML models by applying graph transformation to the meta modeling of dynamic behavior. Within this paper, we extend this approach to also account for time by building on timed graph transformations. We apply these concepts to the domain of multimedia application modeling in which we adopt UML sequence diagrams. The DMM rules with time then specify an interpreter that can be used to analyze or test a model of multimedia sequence diagrams.

Teaching UML is teaching software engineering is teaching abstraction

As the Unified Modeling Language (UML) has by now seen widespread and successful use in the software industry and academia alike, it has also found its way into many computer science curricula. An outstanding advantage of teaching UML is that it enables an illustration of many crucial concepts of software engineering, far beyond its concrete notation. Most important among these concepts is that of abstraction. We present a course design which demonstrates the use of UML as a vehicle for teaching such core concepts of software engineering. Multimedia elements and tools help to efficiently convey the courses message to the students.

Dynamic Meta Modeling with time: Specifying the semantics of multimedia sequence diagrams

The Unified Modeling Langugage (UML) offers different diagram types to model the behavior of software systems. In some domains like embedded real-time systems or multimedia systems, it is necessary to include specifications of time in behavioral models since the correctness of these applications depends on the fulfillment of temporal requirements in addition to functional requirements. UML thus already incorporates language features to model time and temporal constraints. Such model elements must have an equivalent in the semantic domain.We have proposed Dynamic Meta Modeling (DMM), an approach based on graph transformation, as a means for specifying operational semantics of dynamic UML diagrams. In this article, we extend this approach to also account for time by extending the semantic domain to timed graph transformation. This enables us to define the operational semantics of UML diagrams with time specifications. As an example, we provide semantics for special sequence diagrams from the domain of multimedia application modeling.

Design of an agent-oriented modeling language based on graph transformation

The use of UML extension mechanisms for the definition of an Agent-Oriented Modeling Language only fixes its syntax. But agent concepts demand an appropriate semantics for a visual modeling language. Graphs have been shown to constitute a precise and general semantic domain for visual modeling languages. The question is how agent concepts can be systematically represented in the semantic domain and further on be expressed by appropriate UML diagrams. We propose a language architecture based on the semantic domain of graphs and elements of the concrete syntax of UML. We use the proposed language architecture to define parts of an agent-oriented modeling language.