Enhancing UML Connectors with Behavioral ALF Specifications for Exogenous Coordination of Software Components

Connectors are powerful architectural elements that allow the specification of interactions between software components. Since the connectors do not include behavior in UML, the components include the behavior for coordinating the components, complicating the designs of components and decreasing their reusability. In this study, we propose the enrichment of UML connectors with behavioral specifications. The goal is to provide separation of concerns for the components so that they are freed from coordination duties. The reusability of the components will increase as a result of such exogenous coordination. Additionally, using the associated behaviors, we aim to resolve the ambiguities that arise when n-ary connectors are used. We use a series of QVTo transformations to transform UML models that include connector behaviors in ALF specifications into UML models which include fUML activities as connector behavior specifications. We present a set of example connectors specified using the proposed method. We execute the QVTo transformations on the example connectors to produce models that represent platform-independent definitions of the coordination behaviors. We also present and discuss cases from real-life large-scale avionics software projects in which using the proposed approach results in simpler and more flexible designs and increases component reusability.