Sequence Diagram

The highest-value diagram in this list. Time runs down; participants across.

• Format.puml
• Length27 lines
• Includesnone

The source

27 lines of PlantUML, and needs nothing beyond the bundled engine. Copy it, or open the template inside Gnomon and render it as it is.

@startuml

title Sequence Diagram

actor User as U
participant "Web App" as W
participant "API" as A
database "Database" as D

U -> W: Request
activate W

W -> A: API Call
activate A

A -> D: Query
activate D
D --> A: Results
deactivate D

A --> W: Response
deactivate A

W --> U: Display
deactivate W

@enduml

Others in UML and standard diagrams

• Activity / Flow DiagramEarns its place when there are real branches and joins.
• Use Case DiagramActor-to-goal. Dated, but still the clearest way to show scope boundaries.
• Class DiagramBest used for a single bounded context, not a codebase.
• State DiagramForces the awkward questions about duplicate and out-of-order events.
• ER DiagramCardinality is the part people get wrong. Write it explicitly.
• Mind MapFor structuring thinking, not for documenting a system.
• Gantt ChartPlans, not architecture, but it renders from text, so it diffs in review.
• JSON VisualizationVisualises a JSON payload: handy in an API design review.
• Work Breakdown StructureWork breakdown. Useful for scoping a piece of delivery.