Relationships

Relationships define how elements in your architecture communicate with each other. They are a core part of the Structurizr DSL model.

Basic syntax

source -> destination "description"

With technology:

source -> destination "description" "technology"

Examples

user -> webapp "Uses"
webapp -> api "Makes API calls to" "HTTPS/JSON"
api -> db "Reads from and writes to" "JDBC"
api -> emailService "Sends notifications via" "SMTP"

Implicit relationships

Inside an element block, you can use implicit this to define relationships from the current element:

person "User" {
  -> system "Uses"
}

softwareSystem "My System" {
  -> externalApi "Fetches data from" "REST"
}

This is equivalent to:

user = person "User"
system = softwareSystem "My System"
user -> system "Uses"

Relationship properties

Relationships support the same metadata as elements:

user -> system "Uses" {
  tags "Critical" "External"
  properties {
    "Protocol" "HTTPS"
    "SLA" "99.9%"
  }
}

Relationship identifiers

You can assign identifiers to relationships for referencing in views:

rel = user -> system "Uses"

This is optional but useful when you need to reference specific relationships in dynamic views or filtered views.

Styling relationships

Use the styles block to style relationships by tag:

styles {
  relationship "Relationship" {
    color "#707070"
    thickness 2
    style dashed
  }
  relationship "Critical" {
    color "#ff0000"
    thickness 3
  }
}

Supported style properties

Property	Description	Values
`color` / `colour`	Line color	Hex color (e.g., `"#707070"`)
`thickness`	Line thickness	Number (e.g., `2`)
`opacity`	Line opacity	`0`–`100`
`routing`	Line routing	`Direct`, `Orthogonal`
`style`	Line style	`dashed` (solid is default)

Relationships in views

Relationships appear automatically in views when both the source and target elements are included. Use include and exclude to control which elements (and therefore which relationships) are visible:

systemContext mySystem "Context" {
  include *
  autoLayout
}

In dynamic views, relationships are referenced as ordered interaction steps:

dynamic mySystem "Flow" {
  user -> webapp "Submits form"
  webapp -> api "Forwards request"
  api -> db "Queries data"
}

Default tag

All relationships automatically have the Relationship tag. A style like relationship "Relationship" { ... } applies to all relationships unless overridden by more specific tag styles.