Page History

...

Apache NiFi (incubating) processors are typically organized in processor bundles. A processor bundle is generally composed of the following:

• A Maven project that produces a jar containing the of processors
• A Maven project that packages the jar processors into a NAR
• Parent pom for the bundle that builds the processors processor and NAR projects

An example processor bundle from the NiFi distribution is the nifi-kafka-bundle, containing the sub-projects nifi-kafka-processors and nifi-kafka-nar.

...

1. Remove the <parent>...</parent> from the bundle's root pom, or replace it with another desired parent
   
   

2. Add the nar plugin to bundle's root pom (ensure the latest version of the nar plugin is being used):

   <build>

           <plugins>

               <plugin>

                   <groupId>org.apache.nifi</groupId>

                   <artifactId>nifi-nar-maven-plugin</artifactId>

                   <version>1.0.1-incubating</version>

                   <extensions>true</extensions>

               </plugin>

           </plugins>

       </build>

3. Specify the necessary dependency versions in the bundle's processors pom. This is required because the default behavior is for the dependencies to inherit their versions through the nifi-nar-bundle parent, so with a different parent these versions will have to be explicitly set. In addition these dependencies should be changed to provided since they will be provided by NiFi.

Common Dependencies

NiFi provides a mechanism to share common functionality through the concept of ControllerServices. A ControllerService is typically composed of the following:

• A Maven project providing the API (i.e. the Java interface that extends the ControllerService interface)
• A Maven project providing an implementation of the above interface
• A Maven project that packages the implementation in a NAR

To leverage a ControllerService a dependency on the appropriate API artifact would be required (the NAR and implementation would be provided at runtime by NiFi). As an example, to leverage the SSLContextService the following dependency would be added to the pom of the processors jar project:

<dependency>

            <groupId>org.apache.nifi</groupId>

            <artifactId>nifi-ssl-context-service-api</artifactId>

</dependency>

This allows a processor in the given project to define the SSLContextService as follows:

public static final PropertyDescriptor SSL_CONTEXT_SERVICE = new PropertyDescriptor.Builder()

            .name("SSL Context Service")

            .description("The Controller Service to use in order to obtain an SSL Context")

            .required(false)

            .identifiesControllerService(SSLContextService.class)

            .build();

An instance of the service can then be obtained:

final SSLContextService sslContextService = context.getProperty(SSL_CONTEXT_SERVICE).asControllerService(SSLContextService.class);

 The nifi-standard-services module contains the shared APIs that can be leveraged. Browsing this module can provide the groupId, artifactId, and version of the various APIs.