Participants

Participants are the actors in a sequence diagram - users, services, databases, etc.

Syntax

@seq
[participants]
  id:Label
  id:Label|type

Rendered diagram

Basic Participants

@seq
[participants]
  user:User
  web:Web App
  api:API Server
  db:Database

Rendered diagram

Participant Types

Different types render with different styles:

@seq
[participants]
  user:End User|actor
  browser:Browser|client
  api:API Gateway|service
  auth:Auth Service|service
  db:PostgreSQL|database
  queue:RabbitMQ|queue

Rendered diagram

Type	Description	Visual
actor	Human user	Stick figure
client	Client application	Rectangle
service	Backend service	Rectangle
database	Data store	Cylinder
queue	Message queue	Cylinder

Participant Order

Participants appear left-to-right in declaration order:

@seq
[participants]
  # Left to right
  client:Client
  gateway:Gateway
  service:Service
  database:Database

Rendered diagram

Next Steps

• Messages - Interactions between participants

• Examples - Real-world sequences