Extend Validation for Component vs Sequence Diagrams (#245)

Author: xiangu-batw

validation/core/docs/specifications/component_sequence.md

@@ -15,18 +15,30 @@
 
 ## Purpose
 
-Define the intended consistency rules between component-diagram units and the
-participants observed in sequence diagrams.
+Define the intended consistency rules between component-diagram units, the
+participants observed in sequence diagrams, and the internal interfaces used by
+sequence-diagram function calls.
 
-This validator checks whether unit aliases from component diagrams match the
-set of used participants collected from sequence diagrams.
+This validator checks whether:
+
+- unit aliases from component diagrams match the set of used participants
+  collected from sequence diagrams
+- each function used in a sequence interaction is declared in an interface
+  associated with the caller and callee unit and available in the related
+  internal API diagram
 
 ## What is Validated
 
 Component-diagram units and sequence-diagram participants must match. The validator checks:
 
 - unit aliases from the component diagram vs. participant aliases used in sequence diagrams
 - matching is case-sensitive
+- interface connections in the static component diagram vs. function-call
+  connections between the corresponding units in sequence diagrams
+- units connected by function calls in sequence diagrams vs. corresponding
+  interface connections in the static component diagram
+- sequence function names used in interactions vs. method names declared in
+  interfaces referenced by the participating units in the component diagram
 
 ## Failure Cases
 
@@ -35,36 +47,80 @@ Component-diagram units and sequence-diagram participants must match. The valida
 Validation fails when a unit alias defined in the component diagram does not
 appear among the participants used in the sequence diagrams.
 
+### Missing sequence interaction for interface-connected units
+
+Validation fails when units are connected through an interface in the static
+component diagram, but no corresponding function-call interaction between those
+units is specified in the sequence diagram.
+
 ### Unexpected sequence participant
 
 Validation fails when a sequence diagram uses a participant alias that does not
 correspond to any unit alias declared in the component diagram.
 
+### Missing unit interface relation
+
+Validation fails when the caller unit or callee unit has no related interface
+available for function-call validation.
+
+### Missing internal API interface
+
+Validation fails when an interface referenced by the caller or callee unit
+cannot be found in the corresponding internal API diagram.
+
+### Method not found in related interfaces
+
+Validation fails when a function used in a sequence interaction is not declared
+in the related interfaces defined for the caller and callee units.
+
+The validator reports an error when any of the following applies:
+
+- the function is declared only in interfaces related to the caller unit
+- the function is declared only in interfaces related to the callee unit
+- the function is declared on both sides, but not in a shared matching
+  interface
+- the function is not declared in any related interface
+
 ## Debug Output
 
-The validator emits a debug view containing:
+The validator emits debug output containing:
 
 - expected unit aliases
 - observed caller/callee participants
+- observed sequence calls (`caller -> callee : method`)
+- caller and callee interface targets derived from the component diagram
+- interfaces checked in the internal API diagram
 
 ## Example
 
 If the component diagram defines the unit aliases `unit_1` and `unit_2`, then
-the sequence diagrams must use the same participant aliases.
+the sequence diagrams must use the same participant aliases. In addition, a
+function call such as `unit_1 -> unit_2 : GetData(...)` must be backed by an
+interface referenced by `unit_1` and `unit_2` in the component diagram, and
+that interface must declare a `GetData` method in the internal API diagram.
 
 ```plantuml
 ' component diagram
 package "Package A" as package_a <<SEooC>> {
   component "Component A" as component_a <<component>> {
     component "Unit 1" as unit_1 <<unit>>
     component "Unit 2" as unit_2 <<unit>>
+
+    interface "InternalInterface" as InternalInterface
+    unit_1 --( InternalInterface
+    unit_2 )-- InternalInterface
   }
 }
 
 ' sequence diagram
 participant "Unit 1" as unit_1
 participant "Unit 2" as unit_2
 
-unit_1 -> unit_2 : SendSignal
-unit_2 --> unit_1 : Ack
+unit_1 -> unit_2 : GetData()
+unit_2 --> unit_1 : return : Data*
+
+' internal_api diagram
+interface "InternalInterface" as InternalInterface <<interface>>{
+  {abstract} GetData(): Data*
+}
 ```