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Java Spring generator

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


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.

  • Complete example for Kafka is here. Notice information about binding.
              groupId: my-group
            $ref: '#/components/messages/lightMeasured'
            $ref: '#/components/messages/lightMeasured'
  • Complete example for MQTT is here.

From the command-line interface (CLI)

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


    -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
addTypeInfoHeader Only for Kafka. Add type information to message header. No true
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/


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


  1. Clone the repository:

    git clone
    cd java-spring-template
  2. Make sure template has all the dependencies:

    npm install
  3. Install AsyncAPI Generator:

    npm install -g @asyncapi/generator
  4. Run generation:

    # for MQTT protocol test with below
    ag tests/mocks/mqtt.yml ./ --output output
    # for Kafka protocol test with below
    ag tests/mocks/kafka.yml ./ --output output
  5. Explore generated files in output directory

For local development, you need different variations of this command. First of all, you need to know about three important CLI flags:

  • --debug enables the debug mode.
  • --watch-template enables a watcher of changes that you make in the template. It regenerates your template whenever it detects a change.
  • --install enforces reinstallation of the template.

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
  • 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/deserializer 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.


Thanks goes to these wonderful people (emoji key):


📖 💻

Francesco Nobilia


Amrut Prabhu


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