Component Sequence Specification

Purpose

This validator enforces consistency across entities in two diagram types:

• Component diagrams

• Sequence diagrams

It shall make sure that Architectural Elements are consistently named and related to each other.

What is Validated

All comparisons are case-sensitive.

Identifier Consistency

Every unit id from the component diagram must be referenced by a participant uid in the sequence diagrams, and every participant uid must reference a unit id. (Requirement: Tools.ComponentSequenceIdentifierConsistency)

A participant uid is matched against unit ids as follows:

• A qualified uid (containing . or ::) must equal a unit id exactly.

• A single-segment uid is a leaf reference: it matches the unit whose id ends in that segment. It must match exactly one unit; several matches are reported as an ambiguous participant. Write the qualified path as the participant label to disambiguate, for example participant "component_a.unit_1" as unit_1.

A participant uid is the participant’s name as an identifier path; an as alias is a local key for messages and does not take part in the check (plantuml/parser/docs/element-identifiers.md, Rule A′). The special participant name ExternalEndpoint represents an external caller/callee outside the modeled units; it is exempt from Identifier Consistency and may appear in sequence diagrams without a matching component-diagram unit.

' component diagram
component unit_1 <<unit>>
component unit_2 <<unit>>

' sequence diagram
participant unit_1
participant unit_2

Interface-Connection Consistency

Every pair of units connected through an interface in the component diagram must have at least one corresponding function-call interaction in the sequence diagrams, and every cross-unit function call in a sequence diagram must correspond to an interface connection in the component diagram. A cross-unit call is one where the caller and callee are different units; self-calls (caller and callee are the same unit) and any call involving ExternalEndpoint are excluded from this check. (Requirement: Tools.ComponentSequenceInterfaceConnectionConsistency)

Two units are considered interface-connected if either one requires an interface that the other provides (the require/provide match works in both directions). The check itself is undirected and per-pair: a call from unit_1 to unit_2 satisfies the same requirement as a call from unit_2 to unit_1, and once one call has been found for a pair, additional calls between the same two units are not required and do not produce additional errors.

' component diagram
component unit_1 <<unit>>
component unit_2 <<unit>>
interface IData
unit_1 -( IData
unit_2 )- IData

' sequence diagram
participant unit_1
participant unit_2
unit_1 -> unit_2 : GetData()

Interface IDs used in error messages may be package-qualified (e.g. package_a.IData) when the interface is declared inside a package or component in the component diagram.

Failure Cases

Failure case	Validation rule
Missing sequence participant	Identifier Consistency
Unexpected sequence participant	Identifier Consistency
Sequence participant matches multiple units ambiguously	Identifier Consistency
Missing sequence interaction for interface-connected units	Interface-Connection Consistency
Missing interface connection for sequence-connected units	Interface-Connection Consistency

Debug Output

The validator emits debug output containing:

• unit ids derived from the component diagram

• observed participants

• observed sequence calls (caller -> callee : method)

• unit interface targets derived from the component diagram

• interface-connected unit pairs derived from the component diagram