UML Semantics Research Articles

Semantics of UML 2.0 Interactions with Variabilities

Means for the representation of variability in UML 2.0 interactions, as presented in a previous work, are further formalised and given a mathematically formal semantics. In this way, UML 2.0 interactions can be used in the conception and development of system families within domain and application engineering tasks. Following the transition from domain to application engineering as a configuration endeavour, resolution of the variability according to a given configuration is captured by a denotational semantics for plain interactions extended to the features for the specification of variability. An example based on a previous case study explicates the semantics hereby defined.

The Human Semantic Web Shifting from Knowledge Push to Knowledge Pull

This paper introduces the Human Semantic Web (HSW) as a conceptual interface, providing human-understandable semantics in addition to the ordinary (machine) Semantic Web, which provides machine-processable semantics based on RDF. The HSW is structured in the form of a Knowledge Manifold and makes use of Unified Language Modeling (based on the Unified Modeling Language) combined with conceptual browsing to present its information to the user in a way that creates substantial benefits in terms of overview, clarity, and flexibility. The HSW browser Conzilla combines the semantics of RDF with the human-understandable semantics of UML in order to enable more powerful forms of human-computer interaction, such as querying the Semantic Web through Edutella and supporting the concept-in-context methodology. The Semantic Web is discussed in terms of three levels of semantic interoperability: isolation, coexistence, and collaboration. Collaboration, as the highest goal, can be achieved by conceptual calibration, which builds bridges between different ontologies in a bottom-up way, describing their similarities as well as their differences. An example is presented in Conzilla of conceptual calibration between systems for e-commerce. In the closing section, the Nonaka-Takeuchi theory of knowledge creation is discussed, and the HSW is described as a “space for interaction,” where the SECI spiral of knowledge creation can be elevated to the global level. Three possible scenarios are presented: open research, enriching the economy by expanding the value ontology, and negotiating a sustainable future for all.

Using UML models for the performance analysis of network systems

The automated functional and performance analysis of communication systems specified with some Formal Description Technique has long been the goal of telecommunication engineers. In the past SDL and Petri nets have been the most popular FDTs for the purpose. With the growth in popularity of UML the most obvious question to ask is whether one can translate one or more UML diagrams describing a system to a performance model. Until the advent of UML 2.0, that has been an impossible task because the semantics were not clear. Even though the UML semantics are still not clear for the purpose, using ITU recommendation Z.109 with UML 2.0 now released, we describe in this paper a methodology and tool called proSPEX ( protocol Software Performance Engineering using XMI) for the design and performance analysis of communication protocols specified with UML.

Formalizing UML Models and OCL Constraints in PVS

The Object Constraint Language (OCL) is the established language for the specification of properties of objects and object structures in UML models. One reason that it is not yet widely adopted in industry is the lack of proper and integrated tool support for OCL. Therefore, we present a prototype tool, which analyzes the syntax and semantics of OCL constraints together with a UML model and translates them into the language of the theorem prover PVS. This defines a formal semantics for both UML and OCL, and enables the formal verification of systems modeled in UML. We handle the problematic fact that OCL is based on a three-valued logic, whereas PVS is only based on a two valued one.

A discrete-time UML semantics for concurrency and communication in safety-critical applications

We define a subset krtUML of UML which is rich enough to express such modelling entities of UML, used in real-time applications, as active objects, dynamic object creation and destruction, dynamically changing communication topologies, combinations of synchronous and asynchronous communication, and shared memory usage through object attributes. We define a formal interleaving semantics for this kernel language by associating with each model M ∈ krtUML a symbolic transition system STS ( M ) . We briefly outline how to compile models of industrial systems making use of generalisation hierarchies, weak and strong aggregation, and hierarchical state-machines into krtUML. The main aim of the paper is to provide an executable semantics for krtUML suitable for the formal verification of temporal model properties with existing model-checking tools.

Towards an Integrated Graph Based Semantics for UML

Recently, we proposed an integrated formal semantics based on graph transformation for central aspects of UML class, object and state diagrams. In this paper, we explain the basic ideas of that approach and show how two more UML diagram types, sequence and collaboration diagrams, can be captured. For UML models consisting of a class diagram and particular state diagrams, a graph transformation system can be defined. Its graphs are associated with system states and its rules with operations in the class diagram and transitions in the state diagrams. Sequence and collaboration diagrams then characterize sequences of operation applications and therefore sequences of transformation rule applications. Thus valid sequence and collaboration diagrams correspond to derivations induced by the graph transformation system. Proceeding this way, it can be checked for example whether such an operation application sequence may be applied in a specific system state.

Dynamic Semantics of UML State Machines

A clear understanding of the dynamic semantics of UML State Machines is essential for a large and varied audience such as final users of the language, CASE tool builders or method engineers. Our proposal aims at achieving such an understanding by suggesting a different metamodeling approach. This approach is based on a two-layer architecture which puts forward the explicit distinction between the generic behavior represented in a dynamic model (Base Layer) and the behavior represented in relation to a particular situation (Snapshot Layer). Using this architecture as a starting point, a metamodel of UML State Machines is proposed, which consists basically of two UML class diagrams (one diagram for each layer of the architecture) and two maps. These maps represent, respectively, the determination of the initial status and the process performed by a run-to-completion step as defined in the UML semantics.

Motivation and organizational principles for anatomical knowledge representation: the digital anatomist symbolic knowledge base.

Conceptualization of the physical objects and spaces that constitute the human body at the macroscopic level of organization, specified as a machine-parseable ontology that, in its human-readable form, is comprehensible to both expert and novice users of anatomical information. Conceived as an anatomical enhancement of the UMLS Semantic Network and Metathesaurus, the anatomical ontology was formulated by specifying defining attributes and differentia for classes and subclasses of physical anatomical entities based on their partitive and spatial relationships. The validity of the classification was assessed by instantiating the ontology for the thorax. Several transitive relationships were used for symbolically modeling aspects of the physical organization of the thorax. By declaring Organ as the macroscopic organizational unit of the body, and defining the entities that constitute organs and higher level entities constituted by organs, all anatomical entities could be assigned to one of three top level classes (Anatomical structure, Anatomical spatial entity and Body substance). The ontology accommodates both the systemic and regional (topographical) views of anatomy, as well as diverse clinical naming conventions of anatomical entities. The ontology formulated for the thorax is extendible to microscopic and cellular levels, as well as to other body parts, in that its classes subsume essentially all anatomical entities that constitute the body. Explicit definitions of these entities and their relationships provide the first requirement for standards in anatomical concept representation. Conceived from an anatomical viewpoint, the ontology can be generalized and mapped to other biomedical domains and problem solving tasks that require anatomical knowledge.