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Smithy traits

Smithy comes with a powerful annotation system. Annotations in smithy are called traits.

These traits let you associate protocol-specific details to your data models and services.

For instance, an operation can be labelled as compatible with http semantics using the http traits:

namespace foo

@http(method: "GET", uri: "/hello/{name}")
operation Greet {
input: GreetInput,
output: GreetOutput,
errors: [BadInput]

structure GreetInput {
// Matches the {name} hole in the uri path above
name: String

structure GreetOutput {
message: String

structure BadInput {
message: String

Creating your own traits

Smithy makes it really easy to create your own traits:

namespace foo

@trait(selector: is(structure))
string customThing

structure MyStructure {

Regarding Smithy4s handling of traits

Smithy4s automatically creates corresponding values in the generated Scala code, for all the annotations it finds, whether defined in the smithy prelude, or defined by users.

These values can be retrieved via some interfaces that will be documented in a near future.