Java Spring generator

Use your AsyncAPI definition to generate java code to subscribe and publish messages

Usage

AsyncAPI definitions

To have correctly generated code, your AsyncAPI file MUST define operationId for every operation.

In order for the generator to know what names to use for some parameters it's necessary to make use of AsyncAPI specification bindings. here is an example of how to use it:

Kafka

channels:
  event.lighting.measured:
    publish:
      bindings:
        kafka:
          groupId: my-group
      message:
         $ref: '#/components/messages/lightMeasured'
    subscribe:
      message:
        $ref: '#/components/messages/lightMeasured'

here is a complete example

asyncapi: '2.0.0'
info:
  title: Streetlights API
  version: '1.0.0'
  description: |
    The Smartylighting Streetlights API allows you
    to remotely manage the city lights.
  license:
    name: Apache 2.0
    url: 'https://www.apache.org/licenses/LICENSE-2.0'

servers:
  production:
    url: kafka.bootstrap:{port}
    protocol: kafka
    variables:
      port:
        default: '9092'
        enum:
          - '9092'
          - '9093'

channels:
  event.lighting.measured:
    publish:
      bindings:
        kafka:
          groupId: my-group
      operationId: readLightMeasurement
      message:
        $ref: '#/components/messages/lightMeasured'
    subscribe:
      operationId: updateLightMeasurement
      message:
        $ref: '#/components/messages/lightMeasured'
components:
  messages:
    lightMeasured:
      summary: Inform about environmental lighting conditions for a particular streetlight.
      payload:
        $ref: "#/components/schemas/lightMeasuredPayload"
  schemas:
    lightMeasuredPayload:
      type: object
      properties:
        lumens:
          type: integer
          minimum: 0
          description: Light intensity measured in lumens.
        sentAt:
          $ref: "#/components/schemas/sentAt"
    sentAt:
      type: string
      format: date-time
      description: Date and time when the message was sent.

MQTT

asyncapi: '2.0.0'
info:
  title: Streetlights API
  version: '1.0.0'
  description: |
    The Smartylighting Streetlights API allows you to remotely manage the city lights.
  license:
    name: Apache 2.0
    url: https://www.apache.org/licenses/LICENSE-2.0

servers:
  production:
    url: mqtt://localhost:{port}
    protocol: mqtt
    description: dummy MQTT broker
    bindings:
      mqtt:
        clientId: guest
        cleanSession: false
        keepAlive: 0
        lastWill:
          topic: /will
          qos: 0
          message: Guest gone offline.
          retain: false
    variables:
      port:
        enum:
          - '8883'
          - '8884'
        default: '8883'
    
          
defaultContentType: application/json

channels:
  smartylighting/streetlights/1/0/event/{streetlightId}/lighting/measured:
    description: The topic on which measured values may be produced and consumed.
    parameters:
      streetlightId:
        $ref: '#/components/parameters/streetlightId'
    publish:
      summary: Inform about environmental lighting conditions of a particular streetlight.
      operationId: receiveLightMeasurement
      message:
        $ref: '#/components/messages/lightMeasured'

  smartylighting/streetlights/1/0/action/{streetlightId}/turn/on:
    parameters:
      streetlightId:
        $ref: '#/components/parameters/streetlightId'
    subscribe:
      bindings:
        mqtt:
          qos: 0
          retain: false
      operationId: turnOn
      message:
        $ref: '#/components/messages/turnOnOff'

components:
  messages:
    lightMeasured:
      name: lightMeasured
      title: Light measured
      summary: Inform about environmental lighting conditions of a particular streetlight.
      payload:
        $ref: "#/components/schemas/lightMeasuredPayload"
    turnOnOff:
      name: turnOnOff
      title: Turn on/off
      summary: Command a particular streetlight to turn the lights on or off.
      payload:
        $ref: "#/components/schemas/turnOnOffPayload"

  schemas:
    lightMeasuredPayload:
      type: object
      properties:
        lumens:
          type: integer
          minimum: 0
          description: Light intensity measured in lumens.
          x-pi: false
        sentAt:
          $ref: "#/components/schemas/sentAt"
    turnOnOffPayload:
      type: object
      properties:
        command:
          type: string
          enum:
            - on
            - off
          description: Whether to turn on or off the light.
          x-pi: false
        sentAt:
          $ref: "#/components/schemas/sentAt"
    sentAt:
      type: string
      format: date-time
      description: Date and time when the message was sent.

  parameters:
    streetlightId:
      description: The ID of the streetlight.
      schema:
        type: string

From the command-line interface (CLI)

  Usage: ag [options] <asyncapi> @asyncapi/java-spring-template

  Options:

    -V, --version                 output the version number
    -o, --output <outputDir>       directory where to put the generated files (defaults to current directory)
    -p, --param <name=value>       additional param to pass to templates
    -h, --help                    output usage information

Supported parameters

Name	Description	Required	Default
disableEqualsHashCode	Disable generation of equals and hashCode methods for model classes.	No	false
inverseOperations	Generate an application that will publish messages to publish operation of channels and read messages from subscribe operation of channels. Literally this flag will simply swap publish and subscribe operations in the channels. This flag will be useful when you want to generate a code of mock for your main application. Be aware, generation could be incomplete and manual changes will be required e.g. if bindings are defined only for case of main application.	No	false
javaPackage	The Java package of the generated classes. Alternatively you can set the specification extension info.x-java-package. If both extension and parameter are used, parameter has more priority.	No	com.asyncapi
listenerPollTimeout	Only for Kafka. Timeout in ms to use when polling the consumer.	No	3000
listenerConcurrency	Only for Kafka. Number of threads to run in the listener containers.	No	3
connectionTimeout	Only for MQTT. This value, measured in seconds, defines the maximum time interval the client will wait for the network connection to the MQTT server to be established. The default timeout is 30 seconds. A value of 0 disables timeout processing meaning the client will wait until the network connection is made successfully or fails.	No	30
disconnectionTimeout	Only for MQTT. The completion timeout in milliseconds when disconnecting. The default disconnect completion timeout is 5000 milliseconds.	No	5000
completionTimeout	Only for MQTT. The completion timeout in milliseconds for operations. The default completion timeout is 30000 milliseconds.	No	30000
asyncapiFileDir	Path where original AsyncAPI file will be stored.	No	src/main/resources/api/

Examples

The shortest possible syntax:

ag asyncapi.yaml @asyncapi/java-spring-template

Specify where to put the result and define poll timeout:

ag -o ./src asyncapi.yaml -p listenerPollTimeout=5000 @asyncapi/java-spring-template

If you don't have the AsyncAPI Generator installed, you can install it like this:

npm install -g @asyncapi/generator

Run it

Go to the root folder of the generated code and run this command (you need the JDK1.8):

./gradlew bootRun

Generated source contains RabbitMQ docker-compose. So you could use it to test amqp with:

docker-compose -f src/main/docker/rabbitmq.yml up -d

Missing features

See the list of features that are still missing in the component:

• support of Kafka is done based on clear "spring-kafka" library without integration like for mqtt or amqp
• generated code for protocol amqp could be out of date. Please have a look to application.yaml and AmqpConfig.java
• tests for protocol amqp are not provided
• add annotation to the model generation. Consider "@Valid", "@JsonProperty", "@Size", "@NotNull" e.t.c.
• parameters for topics are not supported
• server variables are not entirely supported
• security schemas are not supported
• traits are not supported
• Json serializer/desirializer is used always, without taking into account real content type
• client side generation mode (in general just flip subscribe and publish channels)
• template generation of docker-compose depending on protocol of server, now the rabbitmq is hardcoded

If you want to help us develop them, feel free to contribute.

Contributors ✨

Thanks goes to these wonderful people (emoji key):

Semen 📖 💻

Francesco Nobilia 👀

This project follows the all-contributors specification. Contributions of any kind welcome!