FUML

FUML stands for Foundational UML, commonly written as fUML, and refers to an OMG specification that defines the execution semantics of UML 2.x models. Its primary purpose is to provide a precise, implementation-oriented interpretation of UML behavioral elements so models can be simulated, executed, or translated into running code. FUML focuses on core behavioral constructs such as activities, actions, control and data flow, object creation, state machines, and interactions, while leaving the structural aspects of UML largely as defined by the standard.

The specification does not introduce new modeling elements. Instead, it assigns formal, well-defined meanings to existing UML elements, typically described in terms of a virtual machine that executes activity diagrams and other behavioral diagrams. The emphasis is on determinism and reproducible results to support model-driven development, testing, and prototyping of software-intensive systems, including embedded applications.

FUML is part of the wider effort by the Object Management Group (OMG) to enable executable UML. It is closely associated with the Action Language for Foundational UML (ALF), which provides a textual means of expressing behavior to accompany the graphical semantics of FUML. In practice, FUML, together with ALF, influenced the later Executable and Translatable UML (xtUML) initiative, which combines execution and translation of models into code.

Applications of FUML include model-driven design, simulation of behavioral models, model-based testing, and rapid prototyping. Tool support exists in several UML modeling environments that implement fUML/ALF semantics or provide compatible executable facilities.