Developing apps on the OpenDaylight controller¶

This section provides the information required to develop apps on an OpenDaylight controller. Apps can be developed either within the controller using a Model-Driven SAL (MD-SAL) archetype or via an external app using the RESTCONF API to communicate with the controller.

Overview¶

This section starts app development within an OpenDaylight controller.

Perform the following steps to develop an app:

1. Create a local repository for the code using a simple build process.
2. Start the OpenDaylight controller.
3. Test a simple remote procedure call (RPC) that was created based on the principle of hello world.

Prerequisites¶

The following are the prerequisites for app creation:

• A development environment with the following setup and working correctly from the shell:
  • Maven 3.8.3 or later
  • Java 11-compliant JDK
  • An appropriate Maven settings.xml file. One way to get the default OpenDaylight settings.xml file is:

  cp -n ~/.m2/settings.xml,.orig> wget -q -O - https://raw.githubusercontent.com/opendaylight/odlparent/master/settings.xml > ~/.m2/settings.xml

  For Linux or Mac OS X development operating systems, the default local repository is ~/.m2/repository. For other platforms, the default local repository location varies.

  Building an Example module¶

  Perform the following steps to develop an app:

  Create an Example project using Maven and an archetype called the opendaylight-startup-archetype. For first time downloads, this project will take some time to pull all the code from the remote repository.

  mvn archetype:generate -DarchetypeGroupId=org.opendaylight.archetypes \ -DarchetypeArtifactId=opendaylight-startup-archetype \ -DarchetypeCatalog=remote -DarchetypeVersion= The correct VERSION depends on desired Simultaneous Release: Archetype versions :widths: auto :header-rows: 1 ¶

  OpenDaylight Simultaneous Release	opendaylight-startup-archetype version
  Magnesium Development	1.3.0-SNAPSHOT
  Aluminium Development	1.4.0-SNAPSHOT

  Define value for property 'groupId': org.opendaylight.example Define value for property 'artifactId': example [INFO] Using property: version = 0.1.0-SNAPSHOT Define value for property 'package' org.opendaylight.example: : Define value for property 'classPrefix' Example: : Define value for property 'copyright': Copyright (c) 2021 Yoyodyne, Inc. [INFO] Using property: copyrightYear = 2021

  Note This will create a directory with the name given to artifactId in the above dialog, with the following contents.

  .gitreview api/ artifacts/ cli/ features/ impl/ it/ karaf/ pom.xml src/

  Note Build time varies depending on the development machine specification. Ensure that you are in the project’s root directory (example/,) and then issue the the following build command.

  mvn clean install

  cd karaf/target/assembly/bin ls ./karaf

  opendaylight-user@root>

  log:display | grep Example

  shutdown -f

  Defining a simple HelloWorld RPC¶

  1. Build a hello example from the Maven archetype opendaylight-startup-archetype, same as what was done in the previous steps.
  2. View the entry point to understand the origins of the log line. The entry point starts in the ./impl project:

  impl/src/main/java/org/opendaylight/hello/impl/HelloProvider.java

  /** * Method called when the blueprint container is created. */ public void init()  LOG.info("HelloProvider Session Initiated"); > 

  Add a simple HelloWorld RPC API¶

  1. Navigate to api/src/main/yang .

  cd api/src/main/yang/

  module hello  yang-version 1.1; namespace "urn:opendaylight:params:xml:ns:yang:hello"; prefix "hello"; revision "2021-03-21"  description "Initial revision of hello model"; > rpc hello-world  input  leaf name  type string; > > output  leaf greeting  type string; > > > > 

  cd ../../../ mvn clean install

  Implement the HelloWorld RPC API¶

  1. Define the HelloService that was invoked through the hello-world API.

  cd ../impl/src/main/java/org/opendaylight/hello/impl/

  The HelloProvider.java file is in the current directory. Register the RPC that you created in the hello.yang file in the HelloProvider.java file. You can either edit the HelloProvider.java to match what is below or simply replace it with the code below.

  /* * Copyright © 2021 Copyright (c) 2021 Yoyodyne, Inc. and others. All rights reserved. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/epl-v10.html */ package org.opendaylight.hello.impl; import com.google.common.util.concurrent.ListenableFuture; import org.opendaylight.mdsal.binding.api.DataBroker; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.hello.rev210321.HelloService; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.hello.rev210321.HelloWorldInput; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.hello.rev210321.HelloWorldOutput; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.hello.rev210321.HelloWorldOutputBuilder; import org.opendaylight.yangtools.yang.common.RpcResult; import org.opendaylight.yangtools.yang.common.RpcResultBuilder; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class HelloProvider implements HelloService  private static final Logger LOG = LoggerFactory.getLogger(HelloProvider.class); private final DataBroker dataBroker; public HelloProvider(final DataBroker dataBroker)  this.dataBroker = dataBroker; > @Override public ListenableFutureRpcResultHelloWorldOutput>> helloWorld(HelloWorldInput input)  HelloWorldOutputBuilder helloBuilder = new HelloWorldOutputBuilder(); helloBuilder.setGreeting("Hello " + input.getName()); return RpcResultBuilder.success(helloBuilder.build()).buildFuture(); > /** * Method called when the blueprint container is created. */ public void init()  LOG.info("HelloProvider Session Initiated"); > /** * Method called when the blueprint container is destroyed. */ public void close()  LOG.info("HelloProvider Closed"); > > 

  cd ../../../../../resources/OSGI-INF/blueprint/

  You can either edit the impl-blueprint.xml to match what is below or simply replace it with the XML below.

     Copyright © 2021 Copyright (c) 2021 Yoyodyne, Inc. and others. All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse Public License v1.0 which accompanies this distribution, and is available at http://www.eclipse.org/legal/epl-v10.html -->  xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0" xmlns:odl="http://opendaylight.org/xmlns/blueprint/v1.0.0" odl:use-default-for-reference-types="true">  id="dataBroker" interface="org.opendaylight.mdsal.binding.api.DataBroker" odl:type="default" />  id="provider" class="org.opendaylight.hello.impl.HelloProvider" init-method="init" destroy-method="close">  ref="dataBroker" />   ref="provider"/>  

  cd ../../../../../ mvn clean install