Traits and Values

Traits

Any shape, either a top-level, or a member, may have traits applied and these are represented as follows.

1. The shape resource MAY have any number of properties, named smithy:apply with a blank node value.
   1. This blank node MUST have a property smithy:trait with a value which is the identifier of a top-level shape resource.
   2. This blank node MAY have a property smithy:value representing the trait parameter value - see Value production rules later.

The following example shows traits applied to a top-level shape.

motd:BadDateValue
  a smithy:Structure ;
  smithy:apply [
    smithy:trait api:error ;
    smithy:value "client"
  ] .

The following example shows traits applied to a member shape.

<urn:smithy:example.motd:BadDateValue/errorMessage> 
  a smithy:Member ;
  smithy:target smithy:String ;
  smithy:apply [
    smithy:trait api:required
  ] .

Values

Values are are used in both the model metadata section,

smithy:metadata [
  a rdf:Bag
  rdf:_1 [
    smithy:key "domain" ;
    smithy:value "identity" ;
  ]
] .

as well as in passing parameters to applied traits.

smithy:apply [
  smithy:trait api:title ;
  smithy:value "My new thing"
] .

The following define the production rules for values in either of these cases.

Strings

String values MAY be represented as unqualified string literals OR as qualified strings with the data type xsd:string.

[] smithy:value "My new thing" .

[] smithy:value "My new thing"^^xsd:string .

Booleans

Boolean values MUST be represented as string literals with the type xsd:boolean.

[] smithy:value "true"^^xsd:boolean .

# alternatively, in Turtle:

[] smithy:value true .

Numbers

Number values MUST be represented as string literals with either the type xsd:signedLong or xsd:double.

[] smithy:value "1"^^xsd:signedLong .

[] smithy:value "3.14"^^xsd:double" .

Arrays

Array values MUST be represented as a new blank node.

1. This node MUST have a property rdf:type with the IRI value rdf:Seq.
2. Each property of this blank node follows the standard method to generate predicate names of the form rdf:_{n} with a value using these same production rules.

smithy:value [
  a rdf:Seq ;
  rdf:_1 "experimental" ;
  rdf:_2 "public"
]

Objects

Object values MUST be represented as a new blank node.

1. This node MUST have a property rdf:type with the IRI value rdf:Bag.
2. Each property of this blank node follows the standard method to generate predicate names of the formrdf:_{n} with a blank node value.
   1. This node MUST have a property smithy:key with a string literal for the identifier name.
   2. This node MUST have a property smithy:value with a value using these same production rules.

smithy:value [
 a rdf:Bag ;
 rdf:_1 [
   smithy:key "Homepage" ;
   smithy:value "https://www.example.com/" ;
 ] ;
 rdf:_1 [
   smithy:key "API Reference" ;
   smithy:value "https://www.example.com/api-ref" ;
 ] ;
]

Null

Smithy supports the notion of a null type, this is represented by the specific IRI smithy:null.

[] smithy:value smithy:null .