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Specify Service Protocol Paths with UML 2.x Combined Fragments
Use UML 2.x alt, opt, loop, and break fragments to make service protocol branches explicit before implementation.
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Use UML 2.x alt, opt, loop, and break fragments to make service protocol branches explicit before implementation.
UML 2.5 Combined Fragments (alt, opt, loop, par) model retries, optional flows, and true concurrency in one sequence diagram. Includes a payment-service example, nesting limits, guard portability, and why par needs a companion component diagram.
Combined fragments let you model branching and looping in a single UML sequence diagram. This blog explains the core fragment types, shows a PlantUML example for a payment API, discusses trade‑offs, and gives actionable steps to adopt the pattern.
UML 2.5 combined fragments let modelers interrupt or exclude message flows using break and ignore operators. The goal is to determine the termination scope of a break fragment nested inside a loop operand across all participating lifelines. The UML 2.5 specification describes break behavior informally, so it is unclear whether exiting a break inside a loop a
Interaction Flow Control The Unified Modeling Language (UML) specification defines combined fragments to manage interaction flow through operators such as alt , opt , loop , and par . These fragments allow developers to model conditional logic and concurrency within a sequence diagram. Execution Semantics in Nested Fragments While the individual operators ha
The UML 2.5.1 specification provides the par operator to model concurrent interactions and the critical region operator to ensure atomicity. While these fragments are documented for managing execution flow, ambiguity arises when these operators are nested within one another. The goal is to define a consistent semantic behavior for a critical region placed in