An Arrow of I inputs and O outputs

Semantics of this model

Arrow

• There are a finite number of primitive arrows, PrimArrow

• Each parr::PrimArrow is unique and uniquely identifiable by a name, globally

• There are a finite number of composite arrows, CompArrow

• Each CompArrow is unique and uniquely identifiable by name(arr) globally

Port

• An Arrow has I and O input / output ports

• These I+O Ports are the boundary ports of a CompArrow

• Ports are named name(port) and uniquely identifiable w.r.t. Arrow

• Ports on Arrow are ordered 1:I+O but ordering is independent of whther is_in_port or is_out_port

SubArrow

• A composite arrow contains a finite number of components: SubArrows

• Each SubArrow is unique and uniquely identifiable by name within its parent

• Each SubArrow contains a reference to another PrimArrow or CompArrow

• We can dereference a SubArrow to retrieve the PrimArrow or CompArrow

• A SubPort is a port of SubArrow

• We can dereference it to get the corresponding port on CompArrow / PrimArrow

• a SubPort which is on a SubArrow is not a boundary

Value

• All Ports that are connected share the same Value

• Often it is useful to talk about these ValueSet individually

• a Value is a set of Ports such that there exists an edge between each port ∈ Value, i.e. a weakly connected component

Trace

• SubArrows can refer to CompArrow's, even the same CompArrow

• In execution and other contexts, it is useful be refer to nested

A Composite Arrow: An Arrow composed of multiple Arrows

An interface to an Arrow

Set of Properties

A component within a CompArrow

A Port on a SubArrow