Publishing to AsyncAPI

You can convert events in CDS models to the AsyncAPI specification, a widely adopted standard used to describe and document message-driven asynchronous APIs.

• Usage from CLI
• Presets
• Annotations
• Type Mapping

Usage from CLI

Use the following command to convert all services in srv/ and store the generated AsyncAPI documents in the docs/ folder:

cds compile srv --service all -o docs --to asyncapi

For each service that is available in the srv/ files, an AsyncAPI document with the service name is generated in the output folder. If you want to generate one AsyncAPI document for all the services, you can use --asyncapi:merged flag:

cds compile srv --service all -o docs --to asyncapi --asyncapi:merged

Learn how to programmatically convert the CSN file into an AsyncAPI Document

Presets

Use presets to add configuration for the AsyncAPI export tooling.

.cdsrc.json

{
  "export": {
    "asyncapi": {
      "application_namespace": "sap.example"
      [...]
    }
  }
}

Term	Preset Target	AsyncAPI field	Remarks
merged.title	Service	info.title	Mandatory when --asyncapi:merged flag is given. title from here is used in the generated AsyncAPI document.
merged.version	Service	info.version	Mandatory when --asyncapi:merged flag is given. version from here is used in the generated AsyncAPI document
merged.description	Service	info.description	Optional when --asyncapi:merged flag is given. description from here is used in the generated AsyncAPI document.
merged.short_text	Service	x-sap-shortText	Optional when --asyncapi:merged flag is given. The value from here is used in the generated AsyncAPI document.
application_namespace	Document	x-sap-application-namespace	Mandatory
event_spec_version	Event	x-sap-event-spec-version
event_source	Event	x-sap-event-source
event_source_params	Event	x-sap-event-source-parameters
event_characteristics	Event	x-sap-event-characteristics

Annotations

Use annotations to add configuration for the AsyncAPI export tooling.

TIP

Annotations will take precedence over presets.

Term (@AsyncAPI.)	Annotation Target	AsyncAPI field	Remarks
Title	Service	info.title	Mandatory
SchemaVersion	Service	info.version	Mandatory
Description	Service	info.description
StateInfo	Service	x-sap-stateInfo
ShortText	Service	x-sap-shortText
EventSpecVersion	Event	x-sap-event-spec-version
EventSource	Event	x-sap-event-source
EventSourceParams	Event	x-sap-event-source-parameters
EventCharacteristics	Event	x-sap-event-characteristics
EventStateInfo	Event	x-sap-stateInfo
EventSchemaVersion	Event	x-sap-event-version
EventType	Event		Optional; The value from this annotation will be used to overwrite the default event type in the AsyncAPI document.

For example:

@AsyncAPI.Title        : 'CatalogService Events'
@AsyncAPI.SchemaVersion: '1.0.0'
@AsyncAPI.Description  : 'Events emitted by the CatalogService.'

service CatalogService {
  @AsyncAPI.EventSpecVersion    : '2.0'
  @AsyncAPI.EventCharacteristics: {
    ![state-transfer]: 'full-after-image'
  }
  @AsyncAPI.EventSchemaVersion       : '1.0.0'

  event SampleEntity.Changed.v1 : projection on CatalogService.SampleEntity;
}

Type Mapping

CDS Type to AsyncAPI Mapping

CDS Type	AsyncAPI Supported Types
UUID	{ "type": "string", "format": "uuid" }
Boolean	{ "type": "boolean" }
Integer	{ "type": "integer" }
Integer64	{ "type": "string", "format": "int64" }
Decimal, {precision, scale}	{ "type": "string", "format": "decimal", "formatPrecision": <precision>, "formatScale": <scale> }
Decimal, without scale	{ "type": "string", "format": "decimal", "formatPrecision": <precision> }
Decimal, without precision and scale	{ "type": "string", "format": "decimal" }
Double	{ "type": "number" }
Date	{ "type": "string", "format": "date" }
Time	{ "type": "string", "format": "partial-time" }
DateTime	{ "type": "string", "format": "date-time" }
Timestamp	{ "type": "string", "format": "date-time" }
String	{ "type": "string", "maxLength": length }
Binary	{ "type": "string", "maxLength": length }
LargeBinary	{ "type": "string" }
LargeString	{ "type": "string" }