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Neutron Northbound

How to add new API support

OpenStack Neutron is a moving target. It is continuously adding new features as new rest APIs. Here is a basic step to add new API support:

In the Neutron Northbound project:

  • Add new YANG model for it under neutron/model/src/main/yang and update neutron.yang
  • Add northbound API for it, and neutron-spi
    • Implement Neutron<New API> and Neutron<New API> under neutron/northbound-api/src/main/java/org/opendaylight/neutron/northbound/api/
    • Implement INeutron<New API> and new data structure if any under neutron/neutron-spi/src/main/java/org/opendaylight/neutron/spi/
    • update neutron/neutron-spi/src/main/java/org/opendaylight/neutron/spi/ to wire new CRUD interface
    • Add unit tests, Neutron<New structure> under neutron/neutron-spi/src/test/java/org/opendaylight/neutron/spi/
  • update neutron/northbound-api/src/main/java/org/opendaylight/neutron/northbound/api/ to wire new northbound api to RSApplication
  • Add transcriber, Neutron<New API> under transcriber/src/main/java/org/opendaylight/neutron/transcriber/
  • update transcriber/src/main/java/org/opendaylight/neutron/transcriber/ to wire a new transcriber
    • Add integration tests Neutron<New API> under integration/test/src/test/java/org/opendaylight/neutron/e2etest/
    • update integration/test/src/test/java/org/opendaylight/neutron/e2etest/ to run a newly added tests.

In OpenStack networking-odl

  • Add new driver (or plugin) for new API with tests.

In a southbound Neutron Provider

  • implement actual backend to realize those new API by listening related YANG models.

How to write transcriber

For each Neutron data object, there is an Neutron*Interface defined within the transcriber artifact that will write that object to the MD-SAL configuration datastore.

All Neutron*Interface extend AbstractNeutronInterface, in which two methods are defined:

  • one takes the Neutron object as input, and will create a data object from it.
  • one takes an uuid as input, and will create a data object containing the uuid.
protected abstract T toMd(S neutronObject);
protected abstract T toMd(String uuid);

In addition the AbstractNeutronInterface class provides several other helper methods (addMd, updateMd, removeMd), which handle the actual writing to the configuration datastore.

The semantics of the toMD() methods

Each of the Neutron YANG models defines structures containing data. Further each YANG-modeled structure has it own builder. A particular toMD() method instantiates an instance of the correct builder, fills in the properties of the builder from the corresponding values of the Neutron object and then creates the YANG-modeled structures via the build() method.

As an example, one of the toMD code for Neutron Networks is presented below:

protected Network toMd(NeutronNetwork network) {
    NetworkBuilder networkBuilder = new NetworkBuilder();
    if (network.getNetworkName() != null) {
    if (network.getShared() != null) {
    if (network.getStatus() != null) {
    if (network.getSubnets() != null) {
        List<Uuid> subnets = new ArrayList<Uuid>();
        for( String subnet : network.getSubnets()) {
    if (network.getTenantID() != null) {
    if (network.getNetworkUUID() != null) {
    } else {
        logger.warn("Attempting to write neutron network without UUID");