Foundational UML Reference Implementation
Conformance Statement

The following conformance statement is provided as recommended in Subclause 2.4
of the Semantics of a Foundational Subset for Executable UML Models
specification document.

1. Conformance Level: L3, with limited Dynamic Partial Acceptance. The input
model must be within the fUML abstract syntax subset to be executed. Parts of
the model that are not within this subset may be loaded as "stubs". If an 
attempt is made to access or execute such a stub, a runtime error occurs.

2. Model Library: The Reference Implementation implements all of the Foundation 
Model Library except for BasicInputOutput::ActiveChannel.

3. Abstract Syntax Mapping: The Reference Implementation uses XMI as its input
format. This is loaded into an in-memory representation of a model as instances
of Java classes that are directly generated from the fUML abstract syntax model.

4. Semantic Value Mapping: Internally, all fUML values are implemented 
semantically as instances of Java classes that are directly generated from the 
fUML execution model for values. Input values may be obtained during an 
execution by using the pre-instantiated StandardInputChannel implementation and
values may be output using the pre-instantiated StandardOutputChannel 
implementation.

5. Execution Environment Mapping: The Reference Implementation directly
implements the locus concept as Java classes generated from the fUML execution
model for loci.

   a. Execution takes place at a single locus.

   b. All extensional values are persisted at the execution locus, so long as
   this locus exists.

   c. Single instances of the classes StandardInputChanngel and
   StandardOutputChannel are pre-instantiated at the execution locus.

6. Semantic Conformance: The Reference Implementation implements the entire fUML
execution model through the generation of Java classes from the execution model
itself. This includes a direct implementation of the fUML Executor class as a
Java class implementing all the Executor operations. The Reference
Implementation currently only allows for the synchronous execution of an
activity to be initiated directly from the loaded XMI, but, via its actions,
this activity may evaluate value specifications and execute other activities,
both synchronously and asynchronously.

7. Semantic Constraints

   a. Semantics of time: The Reference Implementation does not provide an
   explicit time model.

   b. Semantics of concurrency: The Reference Implementation serializes all
   execution. Each thread of execution is followed until it blocks, at which
   point another thread is implicitly chosen for execution.

   c. Semantics of inter-object communications mechanisms: The Reference
   Implementation uses normal Java operation calls within a single JVM to
   implement UML inter-object communications.

8. Semantic Variation: The Reference Implementation uses the default semantics
for all semantic variation points. The implementation may be extended with
alternative semantics by providing appropriate semantic strategy class
implementations.