05-identifiers.md

layout	default
title	Identifiers
parent	DSL
nav_order	5
permalink	/dsl/identifiers

Identifiers

By default, all elements and relationships are anonymous, in that they can't be referenced from within the DSL. For example, the following statements will create a person and a software system, but neither can be referenced within the DSL.

person "User"
softwareSystem "Software System"

To create a relationship between the two elements, we need to be able to reference them. We can do this by defining an identifier, in the same way that you'd define a variable in many programming languages.

p = person "User"
ss = softwareSystem "Software System"

Now we can use these identifiers when creating relationships, specifying which elements should be included/excluded from views, etc.

p -> ss "Uses"

Relationships can also be assigned an identifier.

rel = p -> ss "Uses"

Identifiers are only needed where you plan to reference the element/relationship. The following characters may be used when defining an identifier: a-zA-Z_0-9

Identifier scope

By default, all identifiers are treated as being globally scoped, so the following will fail with an error message saying that the api identifier is already in use.

workspace {

    model {
        softwareSystem1 = softwareSystem "Software System 1" {
            api = container "API"
        }

        softwareSystem2 = softwareSystem "Software System 2" {
            api = container "API"
        }
    }
}

The !identifiers keyword allows you to specify that element identifiers should be treated as hierarchical (relationship identifiers are unaffected by this setting) or flat (the default). For example:

workspace {

    !identifiers hierarchical

    model {
        softwareSystem1 = softwareSystem "Software System 1" {
            api = container "API"
        }

        softwareSystem2 = softwareSystem "Software System 2" {
            api = container "API"
        }
    }
}

Now the two API containers can be referenced via softwareSystem1.api and softwareSystem2.api respectively.

Please note that !identifiers hierarchical does not apply to groups.