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This example assumes you are familiar with entity structure of examples and basic command-line usage of avro-compose.jar. If you have not read the simple example README, we recommend reading it before proceeding.
You may incorporate the artifact into your Java project as a dependency and then run the schema generation as a part of project build:
<dependency>
<groupId>com.michalklempa</groupId>
<artifactId>avro-compose</artifactId>
<version>0.0.1</version>
</dependency>
Configure the build phase execution.
<build>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<executions>
<execution>
<id>compose-avro</id>
<phase>prepare-package</phase>
<goals>
<goal>java</goal>
</goals>
<configuration>
<mainClass>com.michalklempa.avro.compose.Main</mainClass>
<arguments>
<argument>--log.level</argument>
<argument>INFO</argument>
<argument>--output.schemas.directory</argument>
<argument>${project.basedir}/src/main/resources/generated</argument>
<argument>--output.schemas.format</argument>
<argument>pretty</argument>
<argument>--output.schemas.filename.template</argument>
<argument>{{ schema.namespace | replace('.', '/') }}/{{ schema.name }}{{ schema.props.outputFileSuffix }}.avsc</argument>
<argument>${project.basedir}/src/main/resources/avro</argument>
</arguments>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
Full example pom.xml can be found in this project.
When using the avro-maven-plugin it is important specify the imports in correct order for the plugin.
Setting up a basic avro-maven-plugin is covered in 1, imports are specifically discussed in 2. Ensuring correct imports ordering can become tedious with growing number of schema files. Avro-compose tool is here to help. From command-line, we can output the default avro-maven-plugin build phase part of pom.xml with imports in correct order:
java -jar avro-compose-0.0.1.jar --output.maven.pom - ./src/main/resources/avro/Should output:
...
<imports>
<import>./src/main/resources/avro/common/Address.avsc</import>
<import>./src/main/resources/avro/common/GPS.avsc</import>
<import>./src/main/resources/avro/common/Location.avsc</import>
<import>./src/main/resources/avro/common/PersonalInformation.avsc</import>
<import>./src/main/resources/avro/common/Department.avsc</import>
<import>./src/main/resources/avro/keys/EmployeeKey.avsc</import>
<import>./src/main/resources/avro/values/EmployeeValue.avsc</import>
</imports>
...
This is correct ordering.
But whats more, you can render the whole pom.xml, just like it is done in this example project.
There is pom_template.xml, which has the import template part:
<imports>
{%- for file in imports %}
<import>{{ file }}</import>
{%- endfor %}
</imports>
This template is transformed into pom.xml by running the avro-compose during the build (snippet from actual pom.xml):
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<executions>
<execution>
<id>compose-avro</id>
<phase>prepare-package</phase>
<goals>
<goal>java</goal>
</goals>
<configuration>
<mainClass>com.michalklempa.avro.compose.Main</mainClass>
<arguments>
<argument>--log.level</argument>
<argument>TRACE</argument>
<argument>--output.maven.pom</argument>
<argument>pom.xml</argument>
<argument>--output.maven.template.file</argument>
<argument>pom_template.xml</argument>
<argument>--output.schemas.directory</argument>
<argument>${project.basedir}/src/main/resources/generated</argument>
<argument>--output.schemas.format</argument>
<argument>pretty</argument>
<argument>--output.schemas.filename.template</argument>
<argument>{{ schema.namespace | replace('.', '/') }}/{{ schema.name }}{{ schema.props.outputFileSuffix }}.avsc</argument>
<argument>${project.basedir}/src/main/resources/avro</argument>
</arguments>
</configuration>
</execution>
</executions>
</plugin>
So this pom.xml file actually rewrites itself during the build. The pom_template.xml is specified using --output.maven.template.file argument.