PlantUML Sequence Diagram Generator

Generate consistent, professional sequence diagrams with standardized styling and documentation patterns.

Initial Questions

Before generating, ask:

•Company Name - For header/footer branding
•Title - Diagram subject (e.g., "Service Flow for XYZ Feature")
•Participant Groupings - Which services belong together? (backend, messaging, external)

Template Structure

plantuml

@startuml sequence
scale 1.5
skinparam responseMessageBelowArrow true

!define _version %date("yyyy.MMdd.HHmmss")
!define _company [CompanyName]

header Confidential\nINTERNAL USE ONLY
title [Title Details]
footer \n<b>_company (c) %date("yyyy")</b>\nVersion _version

autonumber 0.10 20 "<b>[0]"

|||

legend top right
<b><<relay>></b> Passes request as-is
<b><<mediate>></b> Transforms then forwards
end legend

|||

' Components here

' Interactions here

|||
@enduml

Color Assignment (Google Material Design)

Category	Colors	Hex Codes
User's services	Blue	#BBDEFB, #90CAF9, #64B5F6, #42A5F5, #2196F3
External/3rd party	Grey	#ECEFF1, #CFD8DC, #B0BEC5, #90A4AE
Databases	Purple	#E1BEE7, #CE93D8
Cache/Search	Cyan	#B2EBF2, #80DEEA, #4DD0E1
Messaging/Queues	Orange/Amber	#FFE0B2, #FFCC80
Success ops	Green	#C8E6C9, #A5D6A7
Workflow	Indigo	#C5CAE9, #9FA8DA

Control Structure Colors

plantuml

loop#EEEEEE #FFEB3B <color:#000000>description</color>
opt#EEEEEE #009688 <color:#FFFFFF>condition</color>
alt#EEEEEE #4CAF50 <color:#FFFFFF>condition1</color>
else #8BC34A <color:#000000>condition2</color>
par #E0F7FA <color:#B71C1C>system-name</color>
group #4CAF50 <color:#FFFFFF>description</color>

Note Colors

Purpose	Background	Text Color
Field docs (hexnote)	#FBC02D	default
SQL/Query (rnote)	#ECEFF1	#607D8B
Implementation	#FFF9C4	default
Warnings	#F44336	#FFCDD2
Process	#F8BBD0	default
Questions	#D1C4E9	#673AB7

Component Declaration

plantuml

actor "user" as u1

box "Backend Services" #BBDEFB
  boundary "portal" as prt
  control "service" as svc
  control "worker" as wrk
end box

box "Data Layer" #E1BEE7
  queue "rabbitmq" as queue
  database "redis" as cache
  database "mssql" as db
  collections "dbo.Users" AS tbl
  entity "UserModel" as model
end box

participant "External\nProvider" as ext

Component types: actor, boundary (UI), control (services), queue, database, collections (tables), entity (models), participant (external)

Phase Structure

plantuml

== Phase 1: Description ==
autonumber inc A
' interactions
== Phase 2: Description ==
autonumber inc A

Interaction Patterns

Field Documentation (hexnote)

CRITICAL: Hex notes go ABOVE sender, BEFORE the arrow.

plantuml

hnote over prt #FBC02D
""@BATCH_SIZE <color: #795548>1000""
""@TIMEOUT    <color: #795548>30""
====
""ID          <color: #795548>{ID}""
====
""STATUS      <color: #795548>{success, failed}""
""MODIFIEDAT  <color: #795548>sysutcdatetime()""
<i><color #455A64>... (fields omitted)</color></i>
end note
prt -> svc: <<action>>

Structure: Parameters (with @) → ==== → Unique IDs → ==== → Update fields

Array notation:

plantuml

hnote over component #FBC02D
""[]""
  ""FIELD1""
  ""FIELD2""
end note

SQL Queries (rnote)

plantuml

wrk -> db: <<query>>
rnote over db #FAFAFA
<color: #607D8B>""SELECT TOP <color: #B71C1C>@BatchSize""
<color: #607D8B>""FROM dbo.table AS t""
<color: #607D8B>""WHERE t.Status = 1""
end note
db -> svc: <<recordSet>>

HTTP Endpoints

plantuml

' OData (primary)
wrk -> svc: <<createRecord>> \n""POST /odata/resource""
wrk -> svc: <<updateRecord>> \n""PATCH /odata/resource(**{id}**)""
wrk -> svc: <<query>> \n""GET /odata/resource?$top=1""

' REST
wrk -> svc: <<request>> \n""POST /api/classify""

Arrow Types

Arrow	Purpose
`->`	Sync call
`-->`	Sync response
`->>`	Async send
`-->>`	Async callback

Activation

plantuml

component1 -> component2: <<action>>
activate component1
activate component2
component2 --> component1: result
deactivate component2
deactivate component1

Action Verbs

Use camelCase in double angle brackets:

•Lifecycle: <<initiate>>, <<publish>>, <<acknowledge>>, <<notify>>
•CRUD: <<createRecord>>, <<updateRecord>>, <<deleteRecord>>
•Read: <<read>>, <<query>>, <<count>>, <<retrieve>>, <<search>>
•Processing: <<transform>>, <<process>>, <<validate>>, <<decide>>
•Transfer: <<relay>> (as-is), <<mediate>> (transforms)
•Data: <<insert>>, <<upload>>, <<download>>, <<sync>>
•State: <<lock>>, <<unlock>>, <<set>>, <<get>>, <<cache>>

Add context: <<prepare>> records for insertion

Special Elements

plantuml

... batch process ...
... implementation details omitted ...
|||  ' spacing
destroy component1  ' lifeline end

Critical Rules

•Hex notes ALWAYS above sender, NEVER on receiver
•Control structure text MUST be readable (use appropriate <color:> tags)
•OData endpoints preferred over raw SQL calls
•Use rnote spanning components for WHERE clauses
•Double ==== in hex: Parameters → Unique IDs → Fields
•Parameter values: <color:#795548>
•Comments: <color:#455A64>
•Field names in double quotes
•Add ||| spacing before Phase 1 and before @enduml