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Relationships

Relationships describe the connections, data flows and interactions of the elements,
and created with the -> operator:

model {
customer = actor 'Customer'
cloud = service 'Cloud'
customer -> cloud
}

Relationship kinds

Relationships can be “kinded”:

specification {
// Define a relationship kind in specifications
relationship async
}
model {
system1 = system 'System 1'
system2 = system 'System 2'
system1 -[async]-> system2
}

This allows us to express and add more semantics to the interactions between the elements, for instance, from a technology perspective (REST, GRPC, GraphQL, Sync/Async, etc.) or from a business perspective (delegation, inform, accountability, etc.).
It’s up to you to define the relationship kinds that make sense for your context.

Examples

Relationships may be nested

model {
actor customer
service cloud {
component backend
component frontend
frontend -> backend
customer -> frontend
}
}

Relationships may have a title (and better to have one)

model {
actor customer
service cloud {
component backend
component frontend
frontend -> backend 'requests data'
}
customer -> frontend {
title 'opens in browser' // or nested
}
}

Relationships may be tagged

model {
// inlined
frontend -> backend 'requests data' #graphql #team1
// or nested
customer -> frontend 'opens in browser' {
#graphql #team1
}
}

Relationships may have multiple links:

model {
customer -> frontend 'opens in browser' {
// External link
link https://any-external-link.com
// or any URI
link ssh://bastion.internal
// or relative link to navigate to sources
link ../src/index.ts#L1-L10
}
}

Nested relationships may be “sourceless”, then the source is the parent element

specification {
relationship graphql
}
model {
customer = actor {
-> frontend 'opens in browser' // same as customer -> frontend
}
service cloud {
component backend
component frontend {
-[graphql]-> backend 'requests data' // same as frontend -[graphql]-> backend
}
}
// or use 'it' or 'this'
customer = actor {
it -> frontend 'opens in browser'
this -> frontend 'opens in browser'
}
-> backend 'requests data' // ⛔️ Error: model can't be a source
}